CNC Robotics: Build Your Own Workshop Bot

• Provides step-by-step instructions for building your own CNC mochine • Greot for use os 0 teoching tool in metol/wood ...

Author: Geoff Williams

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• Provides step-by-step instructions for building your own CNC mochine • Greot for use os 0 teoching tool in metol/wood shop or on the industriol floor

GEOFF

,WILLIAMS

(J

l

CNC Robotics Build Your Own Workshop Bot

Geoff Williams

McGraw-Hili New York London

Chicago Madrid

San Francisco

Mexico City

New Delhi

San Juan

Singapore

Sydney

Seoul Toronto

Lisbon

Milan

./

Cataloging-i n-Publication Data is on file with the Library of Congress

Copyright © 2003 by The McGraw-Hili Companies, Inc. All rights reserved. Printed in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior written permission of the publisher. 3 4 5 6 7 8 9 0 DOC!DOC 0 9 8 7 6 5 4 ISBN 0-07-141828-8 The sponsoring editor for this book was Judy Bass and the production supervisor wa s Pamela Pelton. It was set in Tiepolo Book by Patricia Wallenburg. Printed and bound by RR Donnelly. McGraw-Hili books are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. For more information, please write to the Director of Special Sales, McGraw-Hili Professional, Two Penn Plaza, New York , NY 10121-2298 . Or contact your local bookstore.

II\ \:CI

Thi s book is printed on recycled, acid-free paper containing a minimum of 50 percent recycled, de-inked fiber.

Information contained in this book has been obtained by The McGraw-Hili Companies, Inc. ("McGraW-Hili") from sources believed to be reliable. However, neither McGraw-Hili nor its authors guarantee the accuracy or completeness of any information published herein, and neither McGraw-Hili nor its authors shall be responsible for any errors, om issions, or damages arising out of use of this information . This work is published with the understanding that McGraw-Hili and its authors are supplying information but are not attempting to render engineering or other professional services. If such services are required , the assistance of an appropriate professional should be sought.

For Margaret, whose help and patience made this book possible.

Contents

II"

II

I

I

1 ,, 1

1

Design Why Build My Own Gantry Style Motors Lineal Motion Motor Drivers Acme Screw Deciding on the Dimensions of the Machine Software

2

Electronics Stepper Motor Driver and Computer In terface Boar ds Stepper Motor Driver Circuit The Interface Board

3

4

Making the Printed Circuit Board

1 I

2 2 4

9 9 9 10

13 13 15 19

77

Tools and Materia l Artwork Board Cutting and Cleaning Toner Transfer Etching

78 82 85 93

Driver Assembly

99

The Interface Board

III

77

v

GNG Robotics

5

Softwa re Setup and Driver Testing Material Needed Creat ing Test Files Triangle Test Circle Test Putting th e Elect ro nics in a Case

6

The Frame Tools and Ma teria l Bolting Assemb ly Bearing Ra il Support Bolt Ho les Paint the Frame

7

The Gantry and X-axis T he Gantry The X -ax is: Insta ll i ng t he Gantry Bearing Guide Rail Beari ng Holder

8

The Z and Y Axes T he Z-Axis The Y-Axls

9

Motor and Lead Screw Insta llat ion Tools and Ma teria l X-axis Y-axls Z-axis Lim it Switc h Install at ion X -axis Limi ts Y-axis Limi ts Z-axis Limits

10

File Creation and KCam KCam CNC Cont rol ler Software KCam File Require ments How to Create a File to Import CorelDraw ACME Profile r

vi

113 113 121

122 123 124

13 3 133 138 141 144 151

1 53 153 160 164

175 175 184

189 189 190 199 203 206 208 209 211

215 215 219 222 223 239

Contents

11

Tool Holders and Testing Tool Holders Penholder Tool Router/Dremel Holder Testing the CNC Machin e

12

Examples Plotter Mechanical Engraving Tool Dremel Tool Ma ster Craft Rotar y Tool Router

Sources of M aterial Electronic Components L297 /L298 Integrated Circuits CANADA United States, California Lineal Motion Distributor Manufacturers Stepper Motors Metal

Index

245 245 246 252 257

263 263 268 271

274 278

293 293 293 293 294 296 296 29 7 300 301

303

vii

Acknowledgments I must tha nk my brother Karl who inspi red me to write this book and my editor Judy Bass w hose fa ith and a ssistance made th e book a rea lity. I'd also like to thank Patricia Wallenburg who assembled my words and images into book form . Judy an d Patr icia have made this book project an extre me ly enjoyabl e expe rience. Finally my tha nks go ou t to a ll the people who have freely shared with me thei r know ledge a nd assistance wh ile I was resea rchi ng and .bui lding my CNC machi ne. I must thank th e following co mpan ies for a llowing me to include some of their cop yrighted materia l in this book. The NuArc Company, Inc. does n' t p romote, endo rse . or wa rra nty an y modified products. NuArc let me reproduce so me of th e imag es from the repair ma nua l of th e copy ca mera I disassembled but they don 't endorse th e use of thei r p roducts for anyt hing ot her tha n the ir origina lly inte nded fu nction . You can co nta ct NuArc at M&R Sa les a nd Service, Inc. I N. 372 Main Street , Glen Ellyn, IL 60 13 7, USA or on the Web at http:/ / www.nua rc.co m. Kellywa re ha s allo wed me to use sc ree n ca ptures of the progra m KCa m 4. Kellywa re ca n be contacted at PO Box 563 . Spirit La ke. Iowa 52 36 0 , USA or on the we b at http:/ / www.kellyware.co m. The p roduct data sheets included with Chapter 2 of th is book have been reprinted with the pe rm iss ion of STMicroelectron ics . The documents reproduced in this book and many more useful app lication notes ca n be found at th e STMicroe lectronics Web site loca ted at http:/ / www.st.co m. Scien ce Speciali st s, Inc. ha s given me permiss ion to include sc ree n captures of th e softwa re ACME Profller, Coyot e Version 6.0. Scien ce Spec ialists, Inc. ca n be rea ched at 1800 Shec kler Rd.. Columbia City, IN 4675 , USA or on th e Web at http t/ zwwwzfwt.co m/ v. klmble/ sc ispec/scispec. htm .

Design

Why Build My Own I first th ought about adding a CNC ro uter to my too l collectio n after fi nishing a kitchen cab inet renovatio n in my home. I refaced the cabinets and bui lt 26 new doors. during w hich I d iscovered t hat door buildi ng can becom e mo noto nou s at best. As always hap pens w hen yo u tell or sho w yo ur fri ends and fam il y w hat yo u have don e, som eone w i ll have a sim ilar p roject and enlist yo ur help . Tha t someone was my frie nd Geoff S. He wanted to do the same thing to his kitchen-reface and install new cabinet doors. I agreed to help him and he decided on a style of doo r that can be ma de from o ne piece of ma terial cut to size and routed to create th e look he wanted . Of cou rse t he prospect of bu il ding a w ho le Jot of doo rs and making temp lates to faci litate the routi ng was n't too thrilling. That's w hen I t ho ught a sma ll CNC machine wo uld co me in han dy. All th e repeti ti ve rou ting cou ld be asslg ned to the CNC mach ine and t he doors w ou ld more closely resemble each other o nce huma n erro r had been removed from t he equation . Now the project didn't seem too bad at all! I started to look for an affordable machine to do the job, After searching the Intern et , I was shocked to find how mu ch the asking pri ce is fo r a CN C mach ine. I did fi nd a cou ple t hat were under

1

1-

CNC Robotics

56000 U.S., bu t I ca n never co nv ince myse lf to buy a too l wo rth so much . Even if the cost of the ma chin e seems reasona ble you st ill have ship ping a nd du ties to pay, and in my case the excha nge ra te be twe en U.S. and Ca na dian dolla rs. All things considered, it was going to cost me in excess of 510,000 Canadian to get a CNC ma ch ine in my shed . I can 't afford that kind of pr ice tag! I sea rched for plans or a book that described what I wanted to bui ld. I did find some plans on the Internet but either the machine was too sma ll and inaccurate or the plans were expensive and requ ired the use of expensive components. I cou ldn 't find any books in print about a similar project. I won't buy plans that I can't get a good look at first , so the Inte rnet plans were out of the qu estion. I prefer books bec a use I ca n ho ld them and flip through the pages before I hand ove r th e cash. Books also cost less. I decide d to build my ow n ma ch ine us ing some off-t he-she lf linea l mot ion co mpo ne nts a nd so me co mpone nts tha t I salvaged or modified to suit the project . I thou gh t the most logica l thing wo uld be to docum ent my p rogress a nd share the inform a tion through a book . To sum ma rize, I deci ded to build my ow n ma chin e because I love a cha llenge a nd I learn mo re whe n I have a pra ctica l project; a lso, I ca n keep the cost low. It's that simple.

Gantry Style In my op inion, a gantry styled CNC mach ine is sim plest to imp lement. A few years ago , I built a ba nd saw mill fram e and gantry, so the design of a more accura te system didn't seem too to ugh a pro ject. I a lso like the idea of moving the tool over the material ra th er tha n the mat er ial under the tool. A mach ine built to move ma teria l would not have as la rge a wo rking a rea for a given footpri nt. Con sidering my work shed is only 22 X 12 feet , a gantry mach ine is most suitable.

Motors The first purchase to make was the stepper motor. My loca l Princess Auto has a grea t s urplus department, so I headed there 2

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Chapter 1 / Design

first. Sure enoug h, they had some step- syn motors (seen in Fig u res 1.1 and 1.2) . They ar e Nema frame size 34 , draw 1.4 amps per cha n nel , and have a rating of 4.6 volts. Figure 1,1 Ste p-Syn steppe r motor side view.

Figure 1.2 Step-Syn ste pper mot or

top view.

U'~

LOT NO.

1'y

o

8201

"; :' 0[ IN .; .\ P A "J

6038285-1

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CNC Robotics

These motors we re used in an IBM produ ct-probabl y a pr inter. They are unipolar, but if yo u run th em as bipolar the y produce more to rqu e (see Figure 1.3). 1 also discovered that t hese steppe r motors work better if t hey are given 12 vo lts ins tead of the 4.6-volt rating on th e motor body. The strength of a s tepper motor is rated in ou nce inches of holding torque. The ste p-sy n information 1 found ind ica ted tha t these motor s ar e an ywhere from 90 to 220 ounce inch es. I so metimes wo rk ba ckward s, and bu ying the motors first is ce rta inly just th at ! Norma lly, you would calculate w ha t strengt h of motor yo u nee d to run th e machine and then p urc ha se a s uita b le motor. Here's how to calculate the st re ngt h of motor you need to run this mach ine. If you can 't find any surplus mo tor s, investigate a company called Pacific Scientific-they ha ve a va riety of s teppe r motors and also make available soft ware for do wnloa d, w hich you ca n use to determine the size of motor yo u ne ed . Spe a king with them , I was impress ed with how we ll I wa s treated, cons ide ring 1 would only need th ree of the ir motors. Remember that although brand new motors ar e expe ns ive, you kno w the y will work and you ca n match the s trength to the machine. New motors could also speed up t he ma ch ine considerabl y. When 1 sa y "speed up ," it is important to not e that I am referring to travel s peeds, not cutti ng s peeds . Cutting speeds for most material s will be slow with this sty le of machine, rega rdless of whi ch motor you choose; you ca n't run a route r thro ugh wood at 200 inches per minute and ex pect the cut to look good . Cutting speeds of 10 to 30 inch es per minu te define the ra nge we can expect from th is mach ine wit h these motors. A faster ma chine can be expected to travel quickly w hen not cutti ng and slow down when cutti ng through mat erial.

Lineal Motion There are a va riety of off-the-shelf lineal motion products , but mo st of the systems we re too expensive for thi s proj ect. Thinking th at it would be useful some day. 1 acq uired a NuArc co py cam era a few years ago (se e Figure 1.4 ), so 1 took it apart and found it 4

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r-----------------------------.-. --~

Chapter 1 /

Design

STEP-SYN 103-820-0240 4.5V 1.4 AMP 2DEG/STEP WIRING DIAGRAM

RED

C

rrI l l '

Wiring diagram of a Step-Syn stepper motor.

+ MOTOR SUPPLY

UNIPOlAR CONNECTKlN

..lAllA}

Figure 1 .3

PHASEA

BLACK REDiWH lTE -

BLUE WHITE

PHASEC

BLUEN/HITE -

PHASE D

BIPOLAR CONNECTIONS BIPOLAR HAlF WINDING (MORESPEED)

r-

PHASE A

RED BLACK -

All Al }

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-

PHASE B

REDfWHITE -

NOr CO NNEC TED

BLUE - -- PHASE C WHITE - - PHASE D BLUEN/HITE-

NOTC O NNEC TED

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BIPOLAR FULL WINDING (MORE lORQUEJ RED -

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BLACK-

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PHASEA ~ W N" NOTCONNECTED !Jk'ir o

REDiWHITE -

PHASE B

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t< 7f' r1"'h H

3.9

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10 = SmA

VSYNC H

3.3

V

10 = 5 mA

VSYNC v

O.B

6111

27

CNC Robot ics

L297·l297D ELECTRiCAL CHARACTERISTICS (continued) Symbol

Pa raneter

T est con d Ition s

Min.

=7V

Typ

Max:.

Un It

I ~.

Leakage current(pin 3)

VeE

1

pA

V~

sat urationvoltage (pin 3)

I ",SmA

0.'

V

V~

Comparators offset voltage (pins 13, 14, 15)

V,.,=. 1 V

s

mV

· 100

'0

pA

0

3

V

~

Comparatorbias curren t (pins 13, 14. 15)

V~

Input refererx:evolage (pin 15)

teu
ed above exceptthat blfilar windings are used to reversethe stator flux, rather than bidirectional drive (figure 6). This motor is driven in exaetlythe sameway as a bipolar motor except that the bri_!>KJ

INHI AND INH2 In ha lf step and one -phase'

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Chapter 2 / Electronics

APPLICATION NOTE

InformatIOntumished is believed to be acceeate and reli able . HowIlvO". SGS- THOMSON ....r cosececocs assumes no respons iMity lor tho consequences 01use 01 such infoonation nor lor any infringement 01 pat ent s or OIher ri!;;tts 01 third parties wh ich may resu lt Itom Us usa . No rcense is granted by implication or othefwi se under any patent or pal ent rq,ts of SGS- Tt-fCltoASON Microeltx:tronic::s. Specificalions mentioned in this ~IOO are sul::gecl to change without notice . This publiealiOn sooeeseoes and replaces aI inlormation previously supplied . SGS-THOMSON Microeledronics producl:s are not alfhoriled lor use as CflficaJ compoosots in life support devices or systems WIthout espeess wn nen approval 01 SGS-THOMSON Microelectronics.

e 1995 SGS-lHOMSON Microeloc:tr onics - AI Riglts Reserved

SGS-THOMSON Mic:roeIectronic GROUP OF COM PANIES

Australia · Bfazj · Prance • Gemlany - Hong Kong • Italy· Japan . x ceea • Ma1aysla . Malra · Morocco - The Nether\and:s • Singapora $pain - Sweden - Switzerland- Taiwan - Th aliand - United Kngdom - U.S.A.

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CNC Roboti cs

51 SGS-1HOMSON ~l ~D©IRJ@~n,rn©1J'IRJ@(Kl]IJ©®

APPLICATION NOTE

STEPPER MOTOR DR IVER CO NS IDERATIONS COMMON PROBLE MS & SOLUTIONS by Thoma s L Hopkins

This not e explains how to avoid same of the more common pitfalls in motor drive design. It is based on the author's expe nence tn responding to enquiries from the field.

Bipolar driven mo tors . In the past unipolar motors were common and preferred for the ir simple drive configurat ions . Howe ver, with the adve nt of cost effective integrated dri ve rs, bipolar motors are now more comrmn. These bipolar motors typi ca lly prod uce a higher torque in a given form factor [lJ.

INTRODUCTION Over the years while working with stepper moto r use rs. many of the same question s keep occ urring from novice as well as experienced use rs of steppe r moto rs. Th is application note is intend ed

as a collection of answers to comroonly asked questions about stepper motors and driver design . In addition the reference list co ntains a number of ot her application notes, book s and art icles that a designer may find usef ul in applyi ng step per moto rs.

Drive Topology Selection Depending on the torque and speed required from a stepper moto r the re are several motor drive topologies available [5, chapter3]. At low speeds a simple direc t voltage drive , giving the motor just sufficient voltage so that the interna l resistance of the motor lim its the current to the allowed va lue as show n in Figure 1A, may be sufficient. However at higher rotationa l spe eds there is a significant fall off of to rque since the winding inductance limits the rate of change of the curr ent and the current can no longer reac h it's full value in each step , as show n in Figure 2.

Throughout the course of this discussion the reader will find referenc es to the L6201 , L6202 and L6203. Since these devices are the same die and differ only in packag e, any refe rence to one of the devices sho uld be considered to mea n any of the thr ee devices . Motor Selection (Unipolar vs Bipolar) Stepper motors in co mmon use can be divided into gene ral classes, Unipolar driven motors and Figure 1: Simple direct voltage unipolar moto rs drive .

A: L/A DAIVE

B: l /nR DRIVE

V.

;::1=-

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Ac I c - Us/ Rc t-Lc / Rc

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APP LICATION NOTE higher voltage is used and the cu rrent limit is set by an external resistor in series with the motor winding such that th e sum of th e extern al resistance and the interna l winding resistance limits the current to the allowed value . Th is drive technique increases the current slew rate and typically provides better torque at high rotational speed . Howe ver there is a significa nt penalty paid In additional dissipation in the extemal resistances. To avoid the additional dissipation a chopping controlled current drive may be employed , as shown in Figure 3. In th is tech nique the current through the motor is sensed and controlled by a choppi ng control circu it so that it is ma intained

Figure 2: Direct voltage drive. A - low speed; B • too high speed generates fall of torq ue.

•

within the rated level. Devices like the L297. L6506 and PBL3717A implement this type of con-

8

,

- - - -- -

trol. This technique improves the current rise time in the moto r and improves the torque at high speeds wh ile maintaini ng a high efficiency in the drive {2] . Figure 4 shows a comparison between the winding current wave forms for the same mo tor drive n in these th ree techniques.

One sol ution is to. use ~hat is com~n ly referred to as an U nR drive (Fig . 18 ). In thls topology a Fig ure 3: Chopper drive provides bette r performance.

us OSCILLATOR

MOTOR ~ INOI NG

SENSE RES ISTO R

Figure 4: Motor current using U R, USR and chopper consta nt current drive.

1. 9

9.5

TIME 2/12 -- - - -- - - -

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CNC Robotics

APPLICATION NOTE In general the best performance, in terms of torque, is achieved using the chopping current control technique [2]. Th is technique also allows

easy implementation of multiple current level drive techniques to improve the motor performance. [1] Driving a Unipolar Motor with the l 298N or L6202 Although it is not the optimal so lution, des ign constrai nts sometimes limit the motor selection, In where the designer is looking for a highly Integrated driv~ stage ~ith improved performance over previous des igns but is constrained to d~ive a unipolar wound (6 leaded) moto~ It IS poss ible to drive the moto r with H-Br iclge drivers like the l298N or L6202. To drive such a motor the center tap of the motor shou ld be left unconnected and the two ends of the common wind ing,s ar~ connected to the ~ridge outputs, as show n In Figure 5. In this configuration the user shou ld notice a marked improvement in torq ue for the same coil current, or put another way, the same torque output will be achieved with a lower coil current. A solution where the L298N or L6202 is used to drive a unipolar motor while keep ing the ce nter c,?nnection of each coil connected to the supply Will not work. First, the protection diodes needed from collector to emitter (drain to source) of the t~e ca~e

transist~rs ~ransformer action

bridge

will be forward biased by the of the motor windings , provid-

In9 an effective short circuit across the supply. Secondly the L298N , eve n though it has split supply voltages , may not be used withou t a high volt age supply on the chip since a portion of the drive current for the outpu t bridge is derived from this supply . Selecti ng Ena bl e or Pha se c hopping Whe!1 implementing chopping control of the current In a stepper motor , there are seve ral ways in which the current control can be imp lemented. A bridqe output, like the L6202 or L298N, may be driven In enab le choppinq, one phase chopping or two p~ase chopping , as shown in Figure 6. The L297 I,mplements enable chopping or one phase choPPII:'!g, selected by the control input. Th e L6506 Implements one phase chopping, with the recirculation path around the lower half of the bridge , if the four outputs are connected to the 4 inputs of the bridge or enab le chopping if the odd numbe red outputs are connected to the enable inputs of the bridge . Selecting the correct chop ping mode is an importan t consideration that affects the stab ility of the system as well as the dissipatio n. Table 1 shows a relative comparison of the different chop ping modes, for a fixed cho pping frequency, motor current and moto r induc tance .

Figu re 5: Driving a unipolar wou nd motor with a bipolar drive

,;,'~-:r

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IH2

>=I

IH3

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~ I

HI-, HI-,

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1

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Figure 3.5 Printer driver set up.

printed from an ink jet printer, but I w asn' t ab le to get the paper off the board. W it h heat , t he surface of the ink jet paper fuses to the copper. If you have p robl ems getting the pape r to free itself from th e bo ard after iro ni ng, th en a little experimentat ion w ill be in order. You mi gh t be abl e to p rint th e artwork w ith a ph otocopier as long as it wi ll use glos sy pap er.

Board Cutting and Cleaning Afte r printing the artwork , I dec ide how big a pi ece of coppe r board I need , then cut it on my li ttle tab le saw using a nonferrous blade (see Figure 3.6 ). Because I have a tendency to purchase material considered sur pl us, I gene rally have a li ttl e extra w ork before I can use it. In this case the PCB materia l is oxi di zed so I will clean it up wit h some supe rf ine steel wool (see Figure 3.7) . Af ter the steel woo l treatment, I wa sh the board w ith d ish soap and hot w ater (as seen in Figure 3.8), making sure t keep my hand s off of th e coppe r. If yo u aren 't ca reful w hen han dli ng the board , you r cleani ng w ill be to no avail because the oil from yo ur fingers will inhibit the

82

Chapter 3

I

Maki ng the Print ed Circuit Board

Figure 3 .6 Cutting PCB material.

Figure 3.7 Shiny copper.

83

CNC Robotics

Figure 3.8

Washing the board.

laser toner fro m adh erin g to the cop per an d could act as a resist w hen etch ing begins. Dry the board thor oughly (see Fig u re 3.9) . Figure 3.9

Drying with paper towel.

14

84

4

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Chapter 3 / Making the Printed Circuit Board

Toner Transfer After pri nt ing t he ar twork. yo u w il l need to a lig n t he two pieces of paper ink side in so that t he toner makes contact with the copper on th e boa rd. Use a stro ng light sou rce or ho ld the paper up to a window to accomplish this task. Or use a light box if you have o ne (see Fig u res 3.10 and 3.11) .

Figure 3 .10 Unaligned art work.

85

CNC Robotics

Figure 3. 11 Aligned artwork.

Now sta ple three sides of the sandwiched pape r to maintain a lignment (see Fig ur e 3. 12). Place the paper sa ndw ich that includes the clea n piece of coppe rclad boa rd, mak ing sure the toner is aligned within the coppe r board (see Figu re 3, 13). Having hea ted the iron to its highest setting, place a clean piece of regu lar paper over the glossy lase r paper. You need to use the regula r pa pe r so tha t the iron won't stick to the laser paper (see Fig ur e 3. 14).

86


Figure 3 .12 Fixing position of art with staples .

Figure 3.13 Inserting the board.

If yo u do n 't use somet hi ng between the glossy paper and the iron , you w ill make a mess of both of th em . J like to iron th e first side a li tt le in ord er to fix it in po sition. Th en I flip over t he w hole sandw ich and start to iron the second side using moderate p ressure for a minute or longer, trying to mak e sure th at I give equ al attention to all ar eas of the bo ard. Next, flip it all over and finish th e first side (see Fig u re 3. 15).

87

CNC Robotics

Figure 3 .14 Using plain paper barrier.

Figure 3.15 Ironing the boa rd.

\

88


In order to set th e to ner, you mu st rin se or imm erse th e sand w ich in cold w ater for a couple of minutes (see Figure 3 .16).

Figure 3 .16 Cold rinse.

Soak ever ything in wa rm w ater for five or ten minutes. After a good soaking, peel th e paper from both sides of th e bo ard (see Figures 3 .1 7 and 3 .18). If the residual paper doesn 't rub off easil y w ith a littl e thumb pressur e, then resoak th e board to loo sen it up (see Figure 3. I 9). After rubbing off the residual paper, t ho roughly check the to ner for mi ssin g sections. If you find any, touch up the area s w ith a permanent marker (see Fig ures 3. 20 and 3 .2 1).

89

CNC Robotics

Figure 3.17 Paper peeli ng.

Figure 3 .18 Thumb rubbin g,

90

Chapte r 3 / Making th e Print ed Circuit Board

Figure 3 .19 Re-soak.

Figure 3 .20 Missing tone r.

Figures 3 .21 Touchup.

.

91

CNC Robotics

Go over t he areas a coup le of ti mes to make sure the copper is well prot ect ed. After lookin g for missing toner, check the holes in th e pa ds an d remove any resid ua l paper by gently scratc hing it w it h a kni fe tip or a pin (see Figures 3.22 and 3.23) . Etching t he copper out of the pad ho les makes dril ling a lot mor e p leasant. It's han dy to use a magnifying glass for the inspection and to uch up. Figure 3 .22 Paper in hole.

Figure 3.23 Scratch it out .

92


Etching W hen yo u are happy w ith the toner resist, proceed to etch the boards. Ferr ic chlo ride will remove all the unprotected copper on th e board. WARN ING: It will also bu rn your ski n, so make su re you use gloves, eye prot ecti on , and a respirato r w hen working w ith thi s etchi ng chem istry. Try to mainta in a good wo rk ing tem peratu re with th e setup (see Figure 3.24). Do n't let th e tempe rature of the w o rking solut io n go high er t han 40 degrees Celsius (104 deg rees Fahren heit). At temperat ure s higher than th at , it will give off some na sty and dangerous fum es.

Figure 3.24 Etching setup .

I like to use a floating thermomete r to keep an eye on the temperature, but any the r mometer shou ld work. Keep checking the board in the ferri c chlo ride solut ion (see Fig ures 3.25 and 3.26) . T he amo unt of t ime required to etc h th e board w ill vary w it h th e temp erature of th e ferri c chloride and how many times the etc hing solu tion has been used. W hen th e bo ard lo ok s like Figu re 3 .2 6, it 's done . Rinse the boar d in clean water to stop t he etc hing (see Figure 3 .27).

93

CNC Robotics

Figure 3 .25 Not finished.

Figure 3 .26 Finished.

94


Figure 3.27 Rinse .

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You ma y need to use a foam pa in tbrush to spot etc h an ar ea if th e rest of the board is fin ished (see Figu re 3 .28 ) . Figure 3.28

Spot etching.

95

CNC Robotics

Now, to ner wi th coppe r unde rneat h is all that rema ins o n t he bo ard . To clean off th e to ne r, I use a rag with some la cq uer t hinner and poss ibly a little soa king in a shallow t ray of t he t hinner (see Figure 3 .29). Figure 3 .29 Toner removal.

The next step is n 't nece ssa ry, but I like the look of a board that ha s been tinned. If yo u wa nt to tin t he board, pick up some tin ning so lutio n a nd set the clea n board in a sha llow tray w ith eno ug h solut ion to cove r it. Wa it until th e copper has a unifo rm deposit an d rem ove and was h th e board . The added benefit to this appli cat ion of tin is t hat so lde ring w ill be a little easier (see Figu re 3.30). Th ese a re the finished boa rds, ready for drilli ng (see Figure 3.31). In this cha pte r yo u cove red how to manufacture printed circuit boa rds for yo ur CNC p roject, so urces for materia ls, as well as w hat methods wo rk best. Now yo u should have t hree d rive r boards an d o ne inte rfac e boa rd etc hed. Etching o ut of the way, the next ch apter s hows you how to drill the req uired holes in your boa rds a nd finish assem bling th em.

96

Chapter 3 /

Making th e Printed Circuit Board

Figure 3.30 Tinning the boards.

Figure 3.31 Etched and t inned.

97

Driver Assembly In order to build the drive r assembl y for the CNC machin e, yo u wi ll need th ese items, as seen in Figure 4. I :

• • • • • • • • • • • • •

Three etched dr iver bo ards One etched interface bo ard Dr il l p ress Dri ll bits Compo nents for each board Solderi ng iron Anti -sta tic w ris t band Pliers Cutter Wire stripper Desol dering tool Multimeter Solder

99

CNC Robotics

Figure 4.1 Tools and material requ ired.

Drilli ng th e hol es for the compo nents is the first step in th e assembly process. This is also t he most tediou s and least- li ked part of any elect ronics pro ject , but a small drill press li ke the one in Fig u re 4.2 and some sharp dri ll bits can mak e a big diffe rence. Figure 4.2 A sma ll drill press.

100

Chapter 4 I Driver Assembly

When the boards we re etched , the hole locati ons in the pads were etched lea ving the fibergla ss exposed . You will find that the dri ll bit will center itself to the bare fiberglas s, allo win g you to drill a little faster and with more a cc uracy t ha n if th e hole location s had not been etched free of copper (see Figu re 4. 3). Figure 4 .3 Closeup of pad hole.

For the resistors, Ie locati ons, and th e through-hole s I used a #60 drill bit. For the diode lead holes and the motor wire location s I used a I I 16-inch drill bit . On the interface board, use a II S- inch drill bit for t he OB25 mou nting holes (see Figu re 4.4). When drilling the holes , it's helpful to place a piece of scra p wood und er the board so as not to damage any of the tra ces. See Fig ure 4 .5. Once you ha ve drilled the component lead hole s, turn on your sol dering iro n. If you have a varia ble- tempera ture so lde ring iron , find a temperature t ha t will allo w you to solde r quickly bu t no t be so hot a s to lift th e pads from the fibergla ss (see Fig u re 4 .6). The method I use to solde r is to hold the tip of th e iron to a plac e on th e pad w he re I can al so ma ke contact with the lead ; th en I apply solder to the pad and lead junction opposite the solde ring iron tip (see Fig u re 4 .7). 101

CNC Ro boti cs

Figure 4 .4 Drill bits required.

1/16 11

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#60 Figure 4.5 Driliing holes in PCB.

•

102

Chapter 4 / Driver Assembiy

Figure 4.6 Soldering iron.

Figure 4.7 Soldering technique.

T he solde r will draw around the lead and pad to t he source of heat . Before yo u to uch any of the ICs make sure yo u have some kind of stati c protection in place. I use a wrist str ap co nnected to ground at the back of my soldering iron (see Fig u re 4.8) .

103

CNC Robotics

Figure 4 .8 Wrist strap stat ic

protection.

Static electricity will de stroy the integrated circ uits. Refer to Figure 4 .9 to determine the p laceme nt of t he components on t he driver boa rd o r Figure 4 . 10 for the interface component p lacement. Sta rt by installing the jump ers on th e topside of the board . You ca n use ins ulated wire (see Figure 4.11) to make the con nection s from one end of the top traces to the other end or you can use a piece of so lid wire or any materia l tha t ca n act a s a conductor from one side of the through-hole to the oth er. On one board, I used pieces of a paper clip cut to extend a little pas t eac h side of the boa rd (see Fig ure 4.12). This method of mimicking a plated t hro ugh -hole requi res the condu cting material to be so ldere d on both sides of the board and ca n be a litt le tricky if th e material doesn 't fit s nug ly in the hole. If the ma te ria l is a little loose, it has a te ndency to slide t hrough and ma y no t actua lly create a connection between top a nd bottom . You can as easily use wire be nt o n bot h side s of the through -hole. If yo u use length s of ins ula ted wire to follow th e tops ide tra ces, yo u on ly need to so lder at the bottom of t he boa rd because the top traces ha ve become jumper guides as oppose d to bei ng th e jumpe rs. After ins tallin g th e jumpers, chec k with a mu ltimete r to e ns ure tha t continuity exis ts between the con nec tions (see Fig u re 4 .13 ). 1 04

Chapter 4 / Driver Assembly

Figure 4 .9 Driver board part placement.

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CNC Robotics

N012 M05 N013 M30 Save this text file as Circl e-gc.txt and test your motors (see Fig u re 5 . 14). After you have succe ssfully tested the driver s and mo tors using Figure 5.14

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KCam and the files you have written , the electronics can be hou sed in an encl osure of your choice.

Putting the Electronics in a Case I am usin g a box from a computer to hou se the dr ivers and th e interface board . I bought the case withou t a power supply for $ I 5 Canadian from a local electronics suppl y store (Fig ure 5.1 5). I removed the power supply holder and the sheet metal used to hold the floppy and hard drives. By removin g the unneeded mounting hardware you free up a lot of space. I deci ded that a fan would be a welcome addition to the box , so I bolted one on the case at the fan opening, as seen in Figure 5 . 16. 124

Chapter 5

I

Softw are Setup and Driver Test

Figure 5.15 Computer box.

•

Figure 5.16 Fan mounted on case .

125

CNC Robotics

Next, I drilled t hree hole s in each of th e driver boa rds and correspond ing hol es on t he moth erboard mo unting surface (see Figure 5 .1 7) . Figure 5.17

Holes drilled to mount drivers.

Use standoffs t hat w il l snap into place (see Figure 5.18). Figure 5.18

Standoff connector. I

126

Chapter 5 / Software Setup and Driver Test

The in terf ace board al so has t hree hol es drilled through it and correspo nding holes in the floor of t he case. The standoffs are high enoug h to allow t he 0825 connecto r to pass through the bottom expansi o n slot opening of th e computer case (see Figure 5.19).

Figure 5.19 Interface board mounted on floor of case .

Next . in stall a 12-term in al connect or st rip for motor w ire att ach ment and a 4- termi na l connecto r strip to supp ly pow er and gro un d to the interface board and fan . an d to provide a p lace to connect t he gro und wi res fro m each of t he d rive r boa rds (see Figure 5.20).

Figure 5.20 1 2- and 4-term inal connectors.

127

CNC Robotics

I us ed th e ground from th e 5-volt and 12- volt s upp ly w ires just as the power supply connectors a re wired (see Figure 5.21) . Figure 5 .2 1 4-terminal connector provides 5 and 12 volts.

The next step is to make cables that will be used to connec t the dri ver boards to the interface boa rd. Pinch the required pin s on to th e w ires that will connect the dri ver 's s tep a nd direction pin s to the interface board a t either end. Connec t a pin to the dri ver end of the wire for the syn c and ground pin s but don 't connec t a pin to the interface end of the se wire s. The sy nc wires ca n be twisted together and protected with electri cal tape. The ground w ires can be twisted togethe r and conn ected to the 5-volt ground terminal on th e 4-terminal connector. At the interface end of the wir es, pla ce each wire in th e connector hole that cor res ponds to the LPT pin you have a ssign ed to ste p and directio n sig na ls for eac h axis. Remember that the pin s on header I of t he inter face board are numbered 1- I8 and are connec ted to t he para llel po rt pin s 1-18 (see Fig u re 5. 22). Install your cabl e w he n it is finish ed . Conn ect th e fan wires to the appropriate voltag e on th e fou r-te rminal connector. The fan used in thi s p roject requ ires 12 volts. 128

- - --

-

-

- - - - - --

--

--

Chapter 5 / Softwa re Setup and Driver Test

Sync wi r e s

Figure 5 .22 Connector at interface end of driver cables.

Use two co mp ute r power supplies , on e to power the boards and motors on the y- a nd z-axes, plu s another to power the boa rd a nd motor of the x-ax is and the cas e fa n. Beca use the hard dr ive and flopp y ba y were remo ved, the two po we r supplies fit nicely in the case, as you ca n see in Figu re 5.23 . Figure 5.23 Power supplies inside

box.

Cut a ho le in the pa nel the powe r supplies, as in Fig ur e 5.24, to a llow the powe r cor ds to be plugged in. Turn the sw itches on a nd tuck the wires you won't use aro und the powe r supplies. 129

CNC Robotics

Figure 5.24 Hole cut in compute r

case panel.

Con nect the motor wires from the dr iver boards in the co rrect sequence on the 12-te rminal connector. Ma ke cables to con nect the motors to the 12-term inal con nec to r with 2- or 3-pair s hie lded cable. Insta ll th e male end of the con nec tor at th e mo tor wire s and the fe ma le end to the cab le (see Figure 5 .25) . Figure 5. 25 Motor to cable connection .

130

Chapte r 5 / Software Setup and Driver Test

Th en co nnect the cables to th e co rrespo nd ing term inal at the 12term inal co nnector (see Fig ure 5. 26) . Figure 5.26 Motor cables connecte d to 12-termin al

connector.

Of course, if a motor doesn't tu rn in the correct d irecti on . ju st reverse the orde r of t he w ires for that mot or at the 12-term inal con nector for you r mac hine to fu ncti on properly af ter the m otors are installed (see Fig ure 5.27). With KCam 4 insta lle d an d set up yo u we re able to perform a few succes sful test s of the drivers an d interface boa rds . After co rrect ing any p roblems, if there we re any, you w il l have mounted t he electron ics in some kind of enclosure. The finished prod uct w ill look tid y and provide some protect ion for the boards. The electro nics are now behind you. In Cha pter 6 you will start construction of your CNC machine by building t he frame.

1 31

CNC Roboti cs

Figure 5.27 Completed box.

132

The Frame

Tools and Material • • • • • • • • • • •

Guide rai l sup po rt mat erial Cross member materia l Cutoff saw or a hacksaw Drill or dr ill press Drill bits N uts and bo lts W i re brush Gri nder Welder (op tional) Clamps Square

As you recall. I decided on the dimensions of the machine (length and width) largely because of the available space in my work area (see Figure 6.1). I really should have built th is a little smaller. because as it stands the foot print will dominate my shed and I will

133

CNC Robotics

Figure 6.1

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Drawing of proposed frame .

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be forced to find a lternative storage for a lot of the ma terial and tools for w hich I don 't have an immediate use. But at the current size, I'll still be able to get around it safely to work. of course, the drawings I made of the machin e are rea lly a guide, as opposed to a strict set of instruct ions. The reason is simple -since I decided on a ga ntry style of machine, the dime nsion that I will most closely follow will be th e footp rint. The material used to const ruct the machine will de termine all the other dimension s. The frame is a good examp le of th is. My drawings use un iform sizes of material in width, height, and thickness, the length being the onl y va ria ble. I am loath to spe nd a lot of mon ey on new steel , so the scrap yard closest to my house is my us ual first stop. It takes a little more effort to find second- ha nd material that will work, con sidering that most of the steel you want is buried under a few tons of steel you don't want. I wa s lucky and found the 3.5- X 3 .5-i nch pieces I am using for the x-axis guide ra il s uppo rts on top of the pile. The ma terial us ed a s cross members was a little deeper but well wo rth the effort to dig out. From the 2.5- X 2. 5-inch materiali used, I cut two pieces 49.5 inches long for e ither end of the frame a nd from th e 3- X 2inc h material I cut th e center cro ss membe r. The leftover material 13 4

Chapte r 6 / The Frame

from the 3.5- X 3.5 -inch mater ial was used to cut the gant ry bea ring s up po rt pieces (see Fig u re 6.2) . Don 't forget to b ring a ta pe mea sure an d a stra ight edge with you to make s ure the stee l you use isn 't wa rpe d o r ben t. Th e guide ra il supports must be straig ht. If they ar e no t stra ight, ad just ing th e ra il heig ht a long the len gth will become more d ifficu lt. And if the cross mem be rs aren't stra ight , the a xis tra vel will be ove r an uneve n s urfa ce, maki ng material positio ning very frustrati ng. Remember that st raig ht is good and ru sty doesn 't ma tter. Figure 6 .2

Scrap stee l.

135

CNC Robotics

A little rust won 't pose a probl em but does a dd clea ning wo rk to th e pro ject. Take a loo k at the rust y material I picked up at the scrap ya rd . The first order of bu sine ss is to c ut th e material to length. I have a n abra sive chop saw to use fo r thi s pu rp ose (see Figu re 6 .3), Figure 6.3 Ste el in saw ready for cut .

The material is heavy enough to tip t he saw w he n clamped in place, so I s up porte d it at th e far end. Ide a lly yo u wa nt a cut t ha t is square to the sides of t he materia l; as lon g a s yo u don 't use the ends as a mating surfac e for a nyt hing du ring cons t ruct ion , squa re cuts don 't matter. Having the pie ce s cut to leng th, I fit th em together upside do wn on a flat s urface, or in my ca se a reall y old , wavy, con crete floor (see Fig u re 6.4). It won 't matter if the s urface is pe rfect bec a use w hen you cla mp the pieces together, the frame will st raighten out. Afte r th e cutt ing a nd fitting (to make s ure I hadn 't made an y mista kes) , I clea ned the surfac es that wo uld be in contact with one an ot her (see Figure 6. 5). 136

Chapter 6 / The Frame

Figure 6.4 Fitting steel in place.

Figure 6.5 Contact surfa ce

cleaning.

The clean ing was accomplished using a wire bru sh mo unted on my s ma ll hand drill , then I we nt over it again using a small orbital sander with 60-grit pape r (see Figure 6,6) , The rough ends from cutting were removed with a grinder a nd a metal fil e. Keep in mind that you ca n lise wha tever too ls you have on ha nd to get the job done. If you only have access to ha nd tools, then cutting and clean ing will just take more time. When the ends are clean, you have two options: bolt them together or weld them together. 1 37

CNC Robotics

Figure 6.6 Drill and sander with

stee l.

Bolting If yo u choose to bol t, then start lay ing out the locati on of th e holes (see Fig ure 6.7), Figure 6.7 Lay out the bolt-hole

locations.

138


The cent er cross rail holes on the bottom of the support beams w ill need to be tapped to accept the bolts. or yo u can dr ill acces s holes to enable the installatio n of the bolts and nuts (see Figure 6.8 ). Figure 6.8 Drill access holes.

Figure shows the bolt access hole locat ion for

center cross member.

D rill all your ho les a little overs ize fo r th e bo lts so tha t yo u w ill have roo m to adj ust the pieces . I li ke to set up my d ril l press vise with tape to mark the locati ons of the holes fro m t he end of t he materi al. In th is case. I used 1-1/ 2 inch centers (see Fig u re 6.9). Figure 6.9

Using tape to mark hole locations.

139

CNC Robotics

I measure t he distance fro m the center of the drill bit to the edge of t he vise to get the cor rect measurement between centers on the w idt h of t he pi ece (sec Fig u re 6.10) .

Figure 6.10 Setti ng centers on width of piece.

W ith a grinder o r fi le. remove t he burrs at the bo lt ho les (see Figu re 6.11).

Figure 6.11 File off burrs .

140

-

- -- - - - -- - -- - - - - _.. - - -


Assembly Put the piece s in place a nd ma ke sure the two ra il suppo rts are para llel and sq ua re to eac h ot her. Butt the ends aga inst a straigh t edge to save a litt le time . Hold a large square, as in Figu re 6.12 , to c heck that the e nds are square. Figure 6.12 Large square at work.

Using a good ta pe mea sure, c heck the distance between the pieces at eithe r end, ma king s ure they a re pa ra llel (see Figu re 6. 13) . Figure 6.13 Making beams parallel.

141

-

--

CNC Robotics

Next. p lace and align the cross members parallel to on e another an d square to the sup port bea ms (see Fig ure 6. I 4). Figure 6.14 Cross-member alignment.

Get out yo ur clamps. I have a number of 4- inch C-c1amps th at w il l do the job. Make sure yo u keep checki ng to see that every thi ng stays in pla ce as you tigh ten the cl am p s. If yo u are bo lti ng. I suggest tr y ing to line up th e bol t hol es as yo u align and square t he fram e. as in Figures 6.1 5 and 6. 16. FIgure 6.15 Clam p wit h bolts.

142

Chapter 6

I The Frame Figure 6. 16 Clamped for welding.

I have an anti que arc we lder th at I p icked up at an auc tio n a few years ago . It works just fine, so I chose to we ld the fr ame together (see Figure 6. 17) .

Figure 6 .17 Ready for welding.

143

CNC Robotic s

You aren't go ing to see a bunch of closeups of my we lds because 1 don 't weld very often. Th ey are n 't pretty, bu t they are st rong enough to keep every thing togeth er. Once t he fram e is together, clean the rest of the rust off the meta l. You can do all this clea ning work prior to assembly; J ju st like to leave the th oro ugh cleaning until th e end (sec Fig u re 6. 18) . Figure 6.18 Thorough cleaning.

Bearing Rail Support Bolt Holes I chose to drill th e bearing rail support bo lt holes befo re painting so t hat I wo uldn 't da mag e the fin ished surf ace. T he bearing rail s are 6 feet lo ng w ith ho les drille d and tapped on I I -i nch centers sta rt ing 3 inches fro m each end (see Figure 6.19) . Figure 6.19 Showing the bolt-hole configuration.

144


I laid o ut the ho les on a piece of masking tape pu lled down the middle of the support rails. 1 like to use ma sking ta pe to lay out drilli ng loca tions so t he marks a re easily vis ible and quickly c ha nge d by rea pplying new ta pe . 1 fou nd t he center of the first s upport bea m a nd drew a line from end to e nd usin g a s tra ight edge (see Fig u re 6 .20) . Figure 6.20 Find center.

Sta rt ing from a chosen e nd, 1 marked the loca tion of ea ch hole a t the ce nt e r line (see Fig u re 6 .21). I t hen taped th e ce nter of th e opp osing s upport bea m an d found the ce nter a t th e e nd a t w hich I had sta rte d marking th e hole locations on th e first be a m (see Fig u re 6 .22). 145

CNC Roboti cs

Figure 6.21 Marking center line.

\

Figure 6.22 Find cente r on second beam.

146


I next measured the dista nce between the center of the first beam and t he center mark I made on the second beam (see Figure 6.23). Figure 6. 23 Getting measurement.

•

.. '

I used this mea surement to ma rk on the opposite end of the secon d beam (Fig u re 6.24) and then drew a line w ith a st raight edge, ensu ring t he tw o li nes were para llel. Figure 6 .24 Marking second beam

for parallel line.

On the seco nd beam, measure t he ho le locati ons from th e same end of the frame you started fro m on the first beam. I did n't wa nt

147

CNC Robotics

to use a handheld drill for the ho les, so I re nte d an electromagnet ic dr ill press, a wo nde rful too l (see Figure 6. 25). Figure 6.25

Electromagnetic drill press.

I se t the dr ill p ress in plac e an d lined it up, fli cked the switch, and it was clamped in p lace. I wa nted th e holes to be a s sq ua re to th e top s urface as possible beca use I need ed to drill access ho les from th e bot tom of the beam under ea ch rail s uppor t bo lt hole (see Figu re 6.26). After dri lling the holes, I pu t a long bit in the chuck an d dr illed through the bottom of the beam to create a guide for the large access ho le (Figu re 6 .2 7). I next flipped the fram e over a nd proceeded to drill th e acces s holes w ith a 3/4- inc h d rill bit (see Figure 6. 28) . 148

Chapter 6

I

The Frame

Figure 6.26 Drilling holes.

Figure 6.27 Drilling acces s hole

guide.

149

CNC Roboti cs

Figure 6 .28 Drilling access hole.

To clean the burrs from the unde rside of the bolt ho le. I pu t a d rill bit in my hand drill and cut the burrs off through t he access ho les (se e Figure 6 .29) . Figure 6.29 Clean off burrs.

150


Paint the Frame Now is a good tim e to paint. Clean the fram e w ith acetone or somet hing th at wi ll remove the ru st du st that came from cleanin g. If you used new mat erial, t hen th e oil cover ing th e metal wi ll need to be remove d. I bought some ru st paint at th e local hardwa re sto re and made the frame pretty. as depicted in Figure 6.30. Figure 6.30 Finished frame .

During this chapte r you decided how big yo ur CNC machi ne wo ul d be and found t he required material to bui ld a frame. After we ldi ng or bolt ing the pieces toget her. you drill ed all th e hol es needed to install th e guide rail s for the x- ax is and fin ished the fram e w ith some paint. The final produ ct is sturdy and attractive. Du ri ng Chapt er 7 you will assembl e a gantry, install guide rail s on the frame, and p ut the gantry on t he guide rail s.

151

;

The Gantry and X-axis The Gantry Tools a nd material s you w ill requi re to build th e ga ntry portion of the CNC ma chine ar e as follows: •

Two 2 X 4 s tee l spa nning beam s

•

Two 2 X 6 stee l uprights

•

Two 3.5 X 3.5 ga ntry feet

•

Drill p ress

•

Abrasive cutoff sa w

•

Welder

The ga ntr y moves the len gth of the x- ax is and ca rries the y- a nd z-axes . It co nsists of two feet on whi ch the bea ring holders are mounted . and two up right po sts that have the ra il holders for the y- ax is spanning between the m. The feet are ma de of 3. 5 X 3.5 steel -the same as the fra me bea ms . cut 12 inch es long (see Fig u re 7.2).

1 53

CNC Roboti cs

Figure 7.1

,......,

,--

lliL

Jil

Drawing of proposed gantr y.

1 54

Chapter 7 / The Gantry and X-axis

Figure 7.2 Gantr y feet with

uprights.

• • :

The uprights are 2 X 6 steel cut 20.5 inches long and the spanning beams are 2 X 4 steel, 48 inches long to span the distance bet ween the t wo upright posts attached to the gantry feet. These spanning beam s are depicted in Figure 7.3 . Figure 7.3

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Spanning beam s .

Pi

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. 155

CNC Robotics

Th e spa nning 2 X 4s are drilled a t eithe r e nd to accommoda te bolts that will be used to attach the m to the upr ights. The location of the bolt holes is det ermin ed by th e distan ce bet ween the ce nte rs of th e gu ide rails mounted on th e fra me beam s (see Figure 7.4).

Figure 7.4 Finding mounting hole location for spanning beams.

The uprights will need to be dr illed to allow t he ce nter of eac h spanning beam to be a t t he ce nte r of th e ra ils th at will be insta lled along thei r len gth (see Fig ure 7. 5).

Figure 7.5 Location of mount ing

holes on uprights.

Also drill two a cce ss ho les on the outs ide of each of t he uprigh ts to a llow th e install ati on of the bolts (see Figure 7.6) .

156


Figure 7.6 Upright access holes.

The n I dri lled holes thro ug h the uprights at t he loca tion w here th e lead sc rew will be inse rted . The location of the lead screw hole s was determined by th e loca tion of t he lea d sc rew nut holde r on the slide I sa lvage d from the copy came ra (see Figure 7_7).

Figure 7.7 Lead screw holes in

upright s.

157

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CNC Robotics

I decided to use t he existi ng hole because the nut fit. I need 13 inches fro m center to center to allow me to use t he bearing holders on t he pla tform I removed from the N uArc copy came ra (see Figure 7.8). Figure 7.8 Cente rs of bearing holders determines the

bolt hole locations on the uprights.

13 1/2 ..

I removed the guide rai ls for t he y -axis from the nuArc copy camera fo r use in my CNC mach ine. They were longer than 1 needed, so I cut of f t he excess with my abrasive cut off saw. The bolt ho les alo ng the length of t he rai ls are at 12- in ch cent ers so I drilled four hol es in each of the spann ing beams directly down t he center of their lengt h on 12-inch centers (see Figu re 7.9) .

158

Chapter 7 / The Gant ry and X-axis

Figure 7.9

.

$ -

Drilling guide rail

t--t---A'~~ ~ 12"

support bolt holes.

T it

Once all t he ho les were dri lled, I clamp ed th e uprigh ts to t he feet w it h the back of t he up rights 2 inches (or th e thickness of the spa nni ng beams) fro m t he end of the feet and as cl ose to cente r as po ssibl e (see Figure 7.10). Figure 7.10

Clamping uprights to feet.

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CNC Robotics

I welded th e upr ight s to the fee t only on the sides a nd fro nt where they me t t he feet. I didn 't weld t he back, so I co u ld rest t he bottom-spa nning beam on the foot witho ut any inte rfe rence (see Figure 7. 11). Figure 7.11 Weld locat ions at gant ry feet .

After we lding t he feet to t he uprig hts , move on to t he next sect ion of t his c hapte r and set up t he rai ls on th e frame.

The X-axis: Installing the Gantry Bearing Guide Rail Tools and mat er ial req uired to instal l t he gantry bearing guide ra il are as follows: •

Guide rai ls (Figure 7. 12)

•

Screwdriver

•

Wrenc h

•

Nuts washers and bo lts

The ho les for the g uide ra il suppo rt bolts we re d rilled d uring t he frame construction process. To be ab le to insta ll the rail , you must raise t he frame to a llow an app roac h to the access ho les d rilled in t he botto m of t he rail suppo rt beam s. I boosted t he frame up wit h a co up le of pa ils I had lyin g a rou nd in my wo rk shed (see Fig u re 7.13) .

160


Figure 7.12 The guide rails.

Figure 7.13 The frame supported with pails .

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CNC Robotics

Insert the first an d last bolts into the beam through the access holes an d tu rn a couple of nuts o nto them (see Figu re 7. 14). Figure 7.14 Inserting the support bolts .

Screw th e first and last bo lts into t he ra il as far a s the y w ill go a nd run one of the nuts to t he be a m, tig hte ning it to ma ke th e bolt rigid. Check th e height of th e ra il at one end and adju st t he opp osite end to match (see Figure z. i s ). Figure 7.15 Finding the working height.

162


Starting in t he middle , install and ad just th e rema ining bolts alternating from the center. Keep checki ng w it h a straight edge to en sur e that th e rail is straight (see Fig u re 7.16) .

Figure 7.16 Checking rail with straight edge.

I

If the ra il isn't straight , you w ill need to raise or low er a support bo lt to st raighten it out. Take your time per form ing this procedu re. Follo w the same seq uence to insta ll the gu ide rail o n t he parallel beam, ma kin g sure you use the heigh t measurement obtained from the first bo lt in stalled on the previou s rai l. If th is is done correctl y, th e rail s sho uld be parallel and at th e sam e heigh t above the beam, wh ile bei ng straig ht w itho ut any defl ection (see Figure 7 . 17) .

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Figure 7.17 Frame with support rails installed.

Bearing Holder Tools and material s required to assemble th e bearing holder include : •

Drill pre ss

•

Drill bits

•

File

•

Tap

•

1- i / 2 X 3 solid aluminum bar stock

You can buy bearing holders for the linear bearings used in thi s project from the manufacturers of the bearings, but 1 decided to make them. The y are much less expensi ve th an th e manufactured model s. I bou ght a length of 3- X I .S-in ch alum inum bar stoc k from t he metal supe rmarket. From thi s stock I cut four pi eces 2 inch es long (see Figure 7. I 9).

164


Figure 7.18

3" (

)

!

Drawing of proposed bearing holder.

I

I I I

1 1/2"

I I

I Wl"

r--

w

-

-'· -r-- --

1 1/4"

J

I

J

I

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o

o

o

o Figure 7.19 Cutting material.

165

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Next, I drilled a ho le in each o ne, 1- 1/4 inches wide to accommodate the outside diameter of the lineal bearings (see Fig ure 7.20) . Figure 7.20 Drilling bearing hole .

I dri lled the ho le 1/4 inch from the bottom of t he stock and then cut out the bottom of t he hole for the bolt clearance (see Figure 7.21). Figure 7.21 Cutting out the clearan ce slot.

166


At 1-1/4 inch from th e side of t he hole, I cu t a notch in the stock to a 1/2 inch fro m th e top . Thi s notch made th e holder ad justable (see Fig u re 7.22) . Figure 7.22 Notch cutting.

I drill ed four hol es from the top down for the bo lt s that wi ll ho ld it to the gantry feet (see Figure 7.23). Figure 7.23 Drilling bearing holder installation bolt holes.

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CNC Robotics

The next hole was drilled from the side of the ho lder until the notch w as reached. This hole had to be tapped to accommodate the adj usting screw (see Figure 7.24). Figure 7.24 Tapping hole for adjusting screw.

Because you ar e working w it h alumi num. tapping isn 't very di ff icult. Wh en all fo ur hol es w ere fini shed. I removed an y ro ugh edges w it h a file. N otice that t he di stance from the top of t he bearing hol e varies a littl e fro m ho lde r to ho lder (see Figure 7.2 5). Figure 7.25 Variance between

holders.

168


Th is difference in dis ta nce can be removed w ith s heet meta l s hims. Beca use my holders were less t han perfect, insta lling them correctly wa s cri tical. I took each of the foot a nd upright sections of the gantry and turne d them upside do wn, placing the bearing holders o n the bottom of the feet w ith bea rings installed (see Figu re 7.26).

Figure 7.26 Holders in place on bottom of gant ry feet .

Ensure that t he holders are positioned w ith the ad justing bolt toward the outer s ide of the feet and mark each ho lder with a correspond ing mark on th e gantry foot. Run one of the rails through th e bearings. Tig hte n t he be a ring holders enough to remove an y play between the ra il and bearings (see Fig ure 7.27).

Figure 7.2 7 Bearing holders adjusted wit h rail.

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CNC Robotics

Usin g a measuring device. align the bearing ho ld ers w ith the rail set to the center of the feet (see Figure 7 .28). Figure 7.28 Cente r the rail to the

feet.

Mark t he holes ' locat ion s th rough the bearing holder onto the feet for the mounting bo lts (see Fig u re 7.29). Figure 7.29

Marking bolt hole locations.

Drill the holes and cle an th e in side of the feet. remo vin g any burrs w it h a fi le.

1 70


Place the ho lde rs back on the bottom of t he feet with bol ts loo sely attached an d determ in e which of th e holders is keepi ng the rail the farthest from th e surf ace of the foo t (see Figure 7.30). Figure 7.30

Finding adjustment height.

T hi s w ill be th e on ly holder that wo n't need a shim . Shim the rem aining t hree ho lders to ra ise t he rail to the height determin ed from th e first hol der (see Figure 7 .31). Figure 7.31 Using shims to even the bea ring holders.

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CNC Robotics

Once the ho lde rs are shim med. tighten the bo lts. ma king su re t he rail is direct ly in the center of the foot . Place each of the feet onto t he rail installed on the fra me. bolt the bottom-spanning beam onto the uprig ht. and then the top-spa nni ng beam (see Figure 7.32) . Figure 7.3 2 Bolt the spanning beams t o the upright s.

172


Tighten the bolts, ensuring th at the beams a re square to the uprights and parallel to the bed of the frame. If you can 't do both , then it's best that the beam be parallel to the bed of t he frame. In any case, the two spann ing beams must be parallel to eac h other, aside fro m t heir relationship to the bed or the up rights. Once the spa nni ng beams are insta lled, the gantry should move easily a lon g the len gth of the rails. Adjust the bearing holders to rem ove a ny excess play but don' t tighte n th em so mu ch that t hey w ill bind. If the feet moved free ly prior to installin g the sp anni ng bea ms, it is possible that the bea ms are pu sh ing the uprights too far apart o r that once tighte ned they may ca use the fee t to toe in or toe o ut. Th is ca n be co rrecte d w ith s hims o n one side of a spa nni ng beam (see Figure 7,3 3). Figure 7.33 Shimming the spanning beams.

With th e ga ntry built and installed o n its gu ide rai ls, you w ill want to ad just the gant ry 's moveme nt us ing s hims and a djust ing t he bea rin g hol der s. Afte r yo u ha ve spe nt a few, pa tien t hours fine- tuning the ga nt ry to e nable it to glide alo ng t he ra ils wit h little effort, yo u are rea dy for Chapte r 8, the z- a nd y-axes insta llation. 173

- - - - - - --

-

-

- --

-

-

-

-

-

-

-

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-

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-

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-

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-

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-

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-

,

The Z and Y Axes The Z-Axis You'll need the fo llowing too ls and materials to build the z- ax ts of the machine.

•

I X 3 metal stock

• • • • •

TV slid ing tra y Hacksaw Drill Dr ill bits Nuts and bolts

The z-ax ts is co nst ructed from a T V ho ld ing glide and tw o pieces of I X 3 foot steel. I boug ht th e TV sli de fr om a big box ho me improvem ent sto re beca use it looked an d felt stu rdy eno ugh to act as th e z-ax ls (see Figure 8.2).

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CNC Roboti cs

Figure 8 .1 Rnished z-axis,

Figure 8.2 TV holder from Home Depot .

1 76

Chapter 8 / The Z and Y Axes

The assembly came w it h a small swi veling tray attached to the sheet metal spannin g the glides. I fi rst drill ed th e r ivet out of the center of th e tab le (see Figure 8.3 ).

Figure 8 .3 Drilling out the table's rivet.

Because t he y-s lide wa s 5 in ch es w ide inside t he outer ridg es (see Fig u re 8.4 ), I needed to cut 4- 3/ 4 inch es from t he center of the sheet metal ho ld ing th e slides togeth er (see Fig ure 8. 5) .

Figure 8 .4 Inside dimension of

y-slide from NuArc copy camera.

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CNC Roboti cs

Figure 8.5 Cut 4-3/ 4 inches from the sheet metal holding the glides together.

Take off the plugs ins ta lled on th e slides (see Fig u re 8 .6 ). Figure 8.6 Remove these plugs.

178

Chapte r 8 / The Z and Y Axes

The n cut a p iece of aluminum to fit across the width of the slide (see Fig u re 8. 7). Figure 8.7 Aluminum z-slide tool mounti ng table .

Dri ll fou r ho les and co untersi nk t he top of each hole on t he aluminum used for the z-tool mou nting surface (see Figu re 8.8). Figure 8 .8 Drill and countersink

table holes.

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CNC Roboti cs

I dr illed two holes on each side of the y-slide w it h corresponding holes on the I X 3 steel used to raise th e z- ax ls assembl y fro m the y-slide surface (see Figure 8. 9) . Figure 8.9 Mounting holes for the

1 X 3 steel.

180


I needed room betwe en th e bott o m of th e z-shde an d th e to p of the y - slide as clearance for the acm e screw bolt hol der to be mounted on th e underside of th e z- sltde. I util ized th e ho les alread y present in the y-s lide at th e bott om for the bea ring block needed to ho ld the acme screw t hat moves the z- slide up and dow n (see Fig ure 8. 10). Figure 8 .10 Location of z-acme screw support bearing.

The bearing block wa s too wide to fit bet ween the 1 X 4 z- sllde supports, so I trimm ed off about 1/ 2 in ch from either sid e and mo di fied the bo lt s I used to hold it dow n (see Fig u re 8 . 11 ). Figure 8.11

Modifications to bearing holder and bolts.

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CNC Robotics

I used the distance from the center of the lower bearing hole to the underside of the z-sl ide to find the cen te r of the hole I drill ed in the angle aluminum that holds the acme screw nul. I then drill ed the ho le the screw wou ld pass th rough . and the holes needed to bo lt the nut ho lde r to the a ngle (see Figure 8 .12) . Figure 8.12 Find the center of acme screw for angle

aluminum . A equals B.

Next I drilled two holes spaced to match th e top two holes dr illed th rough the z- facepla te and slide-bearing sheet me tal (see Figure 8. I 3).

182


Fig ure 8.13 Angle drilled for mounting on underside of z-tabte .

Wi th the z- sli de com plete. I p lac ed it on top of the 1 X 3 rise rs on the y-sli de an d marked hole locat ions to match the top an d bottom hole locat ion s fo r the bo lts to hold th e glides in pla ce (see Fig ure 8.14).

Figure 8 .14 Z-axi s mounting holes.

1 83

CNC Robotics

I tightened th e bottom bo lts first. the n pushed the face plate up to align the to p of the glides. After al ign ing the to p, I tightened th e top bolts. The bolts on th e bott om of th e z-fac epla te cou ld now be tighte ned. bu t I left the top o nes that also s upport the acme screw nu t holder a little loose, as its position wo uld need to se t w hen th e acme sc rew and steppe r motor are insta lled.

The Y-Axis In order to assemble the y-axls, yo u will need th e following tool s an d material s: •

Guide rails

•

Slide from NuArc co py ca me ra (or fo ur ho mema de bearing ho lder s moun ted on an a lum inum plate)

•

Carriage bolts. nuts, a nd was he rs

•

Wrench

The y- ax is es se ntia lly co nsists of the two sp a nning beam s on th e ga nt ry, the bea ring s up po rt ra ils mou nted on the m, and a slide from my disassembled copy ca me ra . The bearings in the slide ar e new, as I was only able to sa lvage four of the bearings from the ca me ra. Because the camera bea rings are the sa me size a s the new o nes I bou ght, they are a perfect fit in the bearing ho lde rs on the slide . To insta ll the rails , I first put the carriage bolts in ea ch of the holes for th e support rails (see Figure 8 .15). I ma de s ure th a t I didn' t run the carriage bol ts too fa r thr ough so they wo uldn 't interfer e whe n I bo lted th e rails a t either e nd. I pla ced the rails through th e bearings on the slide (se e Fig ur e 8 .1 6) and held the top ra il in p lace , so I co uld screw th e bolts at either end of the ra il. Next, I screwed in the end bo lts o n the bott om rail. With the centers of the rails a t the req uired dis ta nce from each oth er, bolting the rail is easy. Remember tha t the holes you drill need to be a bit bigger than the bolts you ' re goi ng to use, so if the ce nters a re a little off, it won 't ma tt er (see Fig ure 8 . 17).

184

Chapt er 8 / The Z and Y Axes

Fig ure 8. 15 Z-axis mount ing holes.

Fig ure 8.16 Insert the rails through the bearings.

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CNC Robotics

Agure 8.17 The rail centers should be at the bearing holder centers.

13 1/2"

Aft er the end bolts are screw ed in . screw in the rest of th e bo lts. but do n't ti ghten anything up yet. The rail s should be the same distance fr om th e spanning beam s and the distan ce from the spa nning beam sho uld allo w the lead screw to ru n t hro ugh the cent er of th e lead screw nut holder locat ion (see Figu re 8. 18). Adj ust the distance to acco mmo date the lead measurin g device and a st raig ht edge. bring same d istan ce from t he spann ing beams and either side of the span ni ng beam to keep them 8. 19).

screw. then. using a the rai ls out to the tighten t he bo lts o n in place (see Fig u re

Adjust t he bearing ho lders to remove any slac k. M ove the y-s lide back an d fort h on th e guide rails and ma ke any ad ju stm ent s necessary to ensu re smo oth sliding. At t his point , yo u wa nt to be cer tain that all of your axes move easily and don't b ind. You have now comp leted th e in sta llation of the z- and y-a xis on th e ga nt ry that tra vels th e x -axis, Mo st of your CNC ma chine is finished. on ly lacking stepper mo tors to give it life. In the nex t chapter, you w ill in sta ll lead screws an d steppe r moto rs to drive each axis.

186


Figure 8 .18 Distance from spanning beam allowing lead

screw to pass through holes in uprights. A equals B.

Figure 8 .19 Use measurement and

straight edge to adjust guide rail.

187

Motor and Lead Screw Installation Tools and Material •

Three steppe r mo tors

•

Three lengths of lead screw cut to size

•

Fiv e p illow blo cks w it h bear ings

•

Three acm e screw nu ts

•

Three nut holders (only two if yo u have fo und a copy camera to cann iba li ze)

•

3 X 3 alu mi num angle iron

•

4 X 4 al uminum squa re materia l

•

J.5 X 4 alum inum ma terial

•

Dr ill

•

Drill bits

•

N uts, washe rs, and bol ts

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CNC Robotics

You w i ll need to fab ric ate mo to r mounts using 4 X 4 al umi nu m. Cut three pieces 4 inches lon g (see Fig ure 9. 1).

Figure 9.1 Cutting motor mounts.

X-axis Th e mount used on th e x- ax is can be drilled in th e cent er for t he motor shaft . I dri lled a 3/4 - i nc h hol e for p lay an d d rilled the fo ur holes to bolt the motor to th e m oun t . Dri ll a 3/ 4-inch center ho le opposite t he motor shaf t openin g and li ne up a pi ll ow block to mar k t he ho les needed to mount it o n the side opposite the moto r (see Figure 9 .2l. I w ant ed the lead screw to run th rough t he foot of the gant ry. so I cut a piece of 1- 1/2 X 4 inch alu min um to rai se th e holder from the beam (see Fig u re 9 .3).

190

Chapter 9 / Motor and Lead Screw Installation

/

/

Figu re 9.2 Drilling holes in motor mount.

Figure 9.3 Spacer for motor mount.

191

CNC Robot ics

I drilled fou r holes in the riser from side to side and four ho les in the motor mount to correspond to the holes in the riser (see Fig ure 9.4) .

Figure 9.4 Holes in riser and motor mount to match .

+ i

~

,

•

t t

t

I fastened th e riser to t he beam using self- ta pp ing screws by inserting a long dr iver bit through the to p hol es to engage the self tapper (see Fig u re 9 .5 ).

192

Chapte r 9 / Motor and Lead Screw Installati on

Figure 9.5 Installing the riser.

'-------------,~--~./ After bo lt ing the motor mount to th e ri ser. I meas ured the distance from the center of t he 3/4-i nch hole in the mou nt to t he beam (see Figure 9.6) .

Figure 9. 6 Lead screw center mea surements.

1 93

CNC Roboti cs

Cut a piece of ang le aluminum on w hic h to mount the acme screw nut. Place the angle alumin um on the foot and mark the center of the lead screw hole using the previou s measurement (see Figu re 9.7) . Figure 9.7 Marking nut holder location on angle

mount.

Dr ill t he lead screw ho le and holes for mo unti ng th e nut hol der as we ll as fou r hol es for bol ti ng the angle aluminum to the ga ntry foot. Tran sfer the hol es' locatio ns to the gant ry foot and drill th em ou t (see Figure 9.8) . Figure 9.8

-

Mou nting position of

nut holder on gantry foot.

. 194

Chapter 9 / Motor and Lead Screw Inst allation

M ount the nu t holder on the angle and run a nut onto a 6-foot length of acme screw. Tighten the nut into the holder (see Fig ure 9.9). Figure 9.9 Acme screw in place .

At the moto r end, install a bea rin g on t he outside of th e mot or mo unt and push the acme screw into place (see Fig ure 9 .10) .

Figure 9.10 Installation of bearing at motor mount.

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CNC Robotics

At the non-motor end of the beam. install another riser and the bearing holder with bearing. and insert the lead screw through the beari ng (see Figure 9.11). Figure 9.11 Installations of riser and bea ring at end of x

travel.

Adjust th e length of sc rew com ing throu gh t he bea ring at the motor mount to allow for t he flexible shaft coupli ng th at w ill connect th e motor to the lea d sc rew. Make sure the lea d sc rew is the sa me height from the beam a t either end . and shim it if necessary (see Figure 9.12). Tighten the lead screw to the bearings with the setscrews. Turni ng the screw by ha nd shou ld be really easy. without binding. If the screw doesn't tu rn easily, ad just the pos itio n of th e lea d screw nut at th e ga ntry foot until the screw will t urn easily t hro ughout its travel. th en tighte n th e nu t ho lder to t he foot (see Figure 9 .13).

196

Chapter 9 /

Motor and Lead Screw Inst allati on

Figure 9.12 Check lead screw position and shim.

Figure 9.13 Adj ust position of nut.

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CNC Robotics

Head back to the motor e nd an d place a flexible coupling on t he lead screw (see Figure 9 .14) . Figure 9.14 Flexible shaft coupling installed.

Insert t he motor s ha ft th rough the 3/4 -inch hole into th e flexible coupling a nd a lign t he motor wit h t he lea d sc rew. Bolt t he mot or in p lace an d tighten the se t screw at th e bearing (sec Figu re 9 . 15). Figure 9 .15 Motor installed.

198


If you did these step s correctly. the motor shou ld be ab le to move the ga ntry fro m one end of the x- ax ls to t he other w it ho ut bind ing. If the lead screw binds. t he motor will stall and lose steps so that w hatever yo u are try ing to make wi ll not turn o ut as expected. T he step- syn motors are st rong enough to ru n thi s axis at 10 inches per min ut e w it ho ut stalling.

V-axis Run a piece of acme screw 55 inch es long thro ug h one side of the gantry ho le and th ro ugh the nu t ho lde r locat ion on t he y -s lide . Turn a nut o nto t he acme screw and inse rt it in to the holder locat ion at th e y-s lid e (see Figure 9. I 6) .

Fig ure 9. 1 6 Inse rting acme screw.

If yo ur threads ma tch. tighten t he nut, or d rill a co up le of holes besi de the nut and inser t two screws to keep th e nut in place (see Figure 9. I 7) .

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CNC Robot ics

Figure 9.17 Screws holding nut in

place.

Befo re you send t he screw t hro ugh th e next gantry up righ t . put it through a bearin g bl ock (see Fig ure 9. 18) . Figure 9.18 Insert lead screw

through a bearing block.

200

Chapter 9 / Motor and Lead Screw Insta llat ion

Also in stall a bear ing blo ck o n t he outside of th e up righ t op posite the motor end (see Fig u re 9. 19 ). Figure 9.19 End of travel bearing

block.

I used self- tap ping screw s to ho ld the bearing bloc ks in p lace. You w ill need to move the acme screw at eit her end to fin d a po sit ion t hat all ows the screw to turn easil y. I sta rted t his qu est by checking the d ista nce from t he to p rail to th e to p of t he screw at t he nut (see Fig ure 9 . 20) and mad e the ends of the screw at the in side of th e up righ ts the same. but it still took a w hile to get it properly align ed.

201

CNC Robotics

Figure 9.20 Rail-to-screw

measurement.

W ith th e acme screw p rop erly ali gn ed. take anot her mo tor mou nt and drill o ut a 3/4 -i nch hole on two opposing sides . Also dr ill mounting holes fo r t he motor t hat are matched on the opposite side for self - tap pers to fasten the mot or mou nt to the upright (see Figure 9.2 1i. Figure 9.21 Holes in mount.

202

Chapter 9 / Motor and Le ad Screw Installation

Place the motor mo un t w it h the lea d screw through the ce nter of the 3/4-inch hole and se lf ta p it to the uprig ht. Place a flexible co up ling on the lead sc rew a nd insta ll the mo to r, a ligned w ith t he screw (see Figu re 9.22). Figure 9 .22 Motor installed .

Z-axis The lea d screw bea ring is already insta lled, as are t he nut holder and t he nut. Cut a piece of acme sc rew 14 inches lo ng a nd screw it th rou gh the nut and into the be aring . Tig hte n the beari ng set screw to ho ld on to t he lea d screw. Drill a 3/4- inc h ce nter hole t hrough both s ides of a motor mo unt and d rill the motor bo lt holes (see Fig u re 9 .23) .

203

CNC Robotics

Figure 9.23 Holes to mount motor.

At the bottom of the motor mount, drill two hol es to take adva ntage of the hole s in the y-s li de to bolt th e mo unt throu gh (see Figu re 9.2 4).

Figure 9.24 Motor mount location on y-sllde .

204


Bolt the mount to the y- slide, making it as square as pos sible to th e lead screw. Insert a fle xibl e cou pl in g on the lead screw and mount the moto r al ign ed w it h the screw (see Fig u re 9.25).

Figure 9 .25 Z motor installed.

1

Make sure the screw turn s easily. W hen it does, tighten the bolts holding the angle aluminum on w hich the lead screw nut is mounted (see Figure 9. 26).

205

CNC Robotics

Figure 9.26 Tighten nut holder

bolts.

Limit Switch Installation The too ls and mate rials req uired to insta ll the lim it sw itc hes are as fo llows :

206

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6 li mit switches

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Chapter 9 / Motor and Lead Screw Installat ion

•

Connect ors for limit sw itches

•

Connect o rs for t he interface board

T he use of limit sw itch es is optional for t hi s mach in e, but you can choose to insta ll them as I did . W ithout li mi t switches installed, the mach ine has no way of ident ifyi ng the boundaries of th e usab le area of the table. If yo ur mach in e isn 't tol d to stop, it wi ll con tin ue to travel past the bo un da ries of t he usabl e area. It w on 't kno w that it has sto pped moving but the motors w ill be tryi ng to turn the acme screw and losing steps w ith every try. Th is wi ll th row your po sitionin g way off. The machine w ill not be abl e to go back to t he home position you have estab lis hed. Of course, leavin g the boundaries sho uld only occur if the th ing yo u want to mak e is wider or longer t han your m achine can handle. You will be able to do this. See if your project is outside the limits of your tab le afte r your file has been imported into KCam. KCam w ill plot the file over the dimensions you have inp ut perta ining to th e size of the X- , y-, and z- axes. As an acc ura cy precaution , limit sw itches are beneficia l. Also KCam 4. 1 wil l not let th e mac hin e ma nuall y home the axis if limit sw itches are not present. I located th e li mit switch es used on t his mach ine at a surp lus store. They aren't really microswitc hes li ke t he ki nd used in pl otters. I thi nk th ey came out of wash ing machines or dr yers; The first clu e was the name Speed Queen on t he side of th e switch (see Figures 9.27 and 9.28). Figure 9.27 Side one of limit switch.

207

CNC Robotics

Figure 9.28 Speed Queen side of limit switch.

These Speed Quee n parts are pe rfect a s limit sw itches since th ey are norma lly open , a nd clo se w hen the plu nge r has been pu sh ed in. Eac h of the a xes requi res two switches-one insta lled at eit her end of travel. The switch needs to ma ke conta ct wit h part of th e moving a xis before the a xis gets ja mmed up.

X-axis Limits On the x-a xis motor end . two ho les ar e nee ded to bolt the limit switch to the top of the motor a nd bearing mount (see Fig u re 9.2 9). Figure 9.29 Location of x home limit

switch.

" 208

Chapte r 9 / Motor and Lead Screw Ins tallation

Eve n thou gh the switch is on a bit of an a ng le. it s till ma kes contact with the ga nt ry and clos es as nee de d. For the limit at the end of x travel. I made a moun t to bolt the swi tch to; th is in turn is sc rewed to the bearing ho lde r. It is insta lled on an an gle to allow the p lunger to ma ke co nta ct with the ac me screw nut holder at the fron t of the ga ntry foot (see Fig ur e 9 .3 0) . Figure 9.30 Limit switch at end of x-axis trave l.

Y-axis Limits The switch at the home position of the y- ax is is mounte d o n a p iece of l - Inch angle al um inum tha t is screwed to the inside of th e gantry upright . e nabli ng the plunger to ma ke conta ct with a bolt pro tr ud ing fro m the side of the y-sli de (see Fig u re 9.31).

209

CNC Robotics

Figure 9 .31 Y-axis home position limit switch locatio n.

The y-ax is end-of- travel limi t swi tc h is also mou nted on an angle bracket. w hich is screwed to t he ins ide of the up right (see Fig ure 9.32). Self-tapping screws are usually useful here. Figure 9.32 Switch at e nd of y-axis

travel.

210

Chapte r 9 / Motor and Le ad Screw Ins tallation

Z-axis Limits To insta ll t he home po sit ion limit sw itch fo r th e z- axls, a spacer is ne ed ed to move t he plunger into a position that will a llow the a cme sc rew nut holde r to mak e co ntact. The s pa ce r is 1/2 - inc h a lum inum ba r cut t he size of th e switch body. Drill two ho les in the ba r th at co rrespond to the holes on the sw itch bod y. Next, dr ill th e same hole pa ttern in the I X 3 riser mount ed on t he y-sll de a t a position that allows the most z trave l (see Figure 9. 3 3) . Figure 9 .33 Z-axis limit switch at home posit ion.

The e nd-o f- trave l limit switc h for t he z-ax is is installed wit ho ut a spacer beca use t he be a ring block mou nted on t he y-sllde wo n 't a llow one to be used . Drill two holes in the I X 3 to a llow t he switc h to be installed. Addition a lly. d rill a hole a bove the posit ion the bod y w ill be in. so t he wire used to a ttac h th is limit swit ch ca n be fed up thro ugh th e I X 3 to th e home limit switch (see Figu re 9. 34) .

211

CNC Robotics

Figure 9.3 4 Position of the z-axis end-ot-treve l limit

switch.

The problem enc ountered by mounting the sw itc h directly to the side of the I X 3 is that nothi ng w ill hit the plunger w hen th e zaxis reaches it s end . To reso lve thi s challenge. make an extension fro m a piece of I I S- inch thi ck by 3/ 4-i nch w ide alumin um . D ri ll a hole so t hat one of t he bo lts hold ing t he acme nut ho lder in p lace can be used to insta ll it. Cut th e co rner on an angl e to give the exte nsion more sur face area t hat can make contact w it h the p lunge r of t he li mi t sw itch (see Figure 9 .3 5) . Figure 9 .35 Extension to activate limit switch.

212

Chapter 9 / Motor and Lead Screw Installat ion

Both of th e switches on each of t he th ree axes are w ired in parallel so that w hen either of t he plungers is engaged the machi ne w il l stop movi ng. Only one pin of the pa ralle l port is used per ax is so the switches need to be wired as in Fig ure 9.36 . Co n nect t o Jp2,3,4 o r 5 on interface b oard

Figure 9.36 Wire the axis limit switches in parallel.

The wire connecting the end-of-travel switch on the x-axis can be fed through the frame beam to the home limit switch and t he endof-travel y- ax is switch wire can be fed through the top spanni ng beam of the gantry to reach th e y home switch. At all of the home switches. connect enough wire to the poles to allow the machine to move to any position on t he w orking area of the table wit hout 21 3

CNC Robotics

being under stress. The distan ce of your elect ro nics from th e machine w i ll also det ermine the length of t he cable. At the end of each cable install a tw o-hol e connector to fit the head er material used on the interface boa rd. Plug each w ire into either lp z , 3. 4. or 5 of the interface board and make sure you open th e LPT set up wi ndow in KCam so tha t you can assign t he correct pin for each of your limit switch circuits (see Figure 9.37) . Figure 9.37 Interface limit switch connection locations.

Your CNC machin e now has all of th e motors. lead screws , and li mit sw itc hes ins ta lled. The Workshop Bot is co mp lete. Chap ter 10 w ill show yo u w hat kind of file s yo u' ll need to run yo ur machine and how to mak e th em .

214

File Creation and KCam

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KCarn CNC Controller Software To complete th is sectio n of your CNC robot ics pro ject , yo u will need to have KCam insta lled and co nfigu red fo r your mach ine. If you haven 't al ready in stalled KCam, visit the Kell yware Web site at www.kellyware.co m and downl oad the dem o versio n of KCam 4. T he demo will ru n fully funct io nal for 60 days, w hic h sho uld be more t han enough time to fi ne- t une your mac hine set up and start w o rking on all the projects you conceived w hile buil ding th e w orkshop bot. Chapter 5 has exp lained sett i ng up KCam in order to test your driver boards. In testing. it really d idn 't matter if all the parameters of you r machine had been establi shed, but it no w do es. Open KCam, click on Setup and open th e Table Setu p win dow. Ensu re that th e number of steps per inch and the ph ys ical dimension for each axi s on your machine are correct. Next, u ncheck t he Limit Switches Disabled button, cl ick Apply and close the window (see Fig u re 10.1).

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If you are using surplus stepper motor s li ke t he step-syn motors on t his ma chine, t he maximum rate of travel for each ax is w ill probably be aroun d 15 inc hes per minute. You w ill need to experim ent to di scover th e fastest rate of travel for your ma chin e. Wh en you are running th e mach ine too fast , th e step per mot or s w il l sta rt to skip turn s. Wi th steppers , the faster you ru n th em , th e lower their torqu e become s and the load they can move decreases dra mati call y. Keep in mind that every time you cha nge t he rat e of trave l you need to run the system timi ng ut il it y. Next , click o n setup and ope n t he Port Setup w indow. Choose w hich pins yo u are assigning to each of t he drivers fo r their step and d irect ion sig nals and w hich pins you are using for the limit switch circuits (see Figure 10.2).

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Chapter 10 / File Creation and KCam

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eNG Robotics

Click on the View butto n and open th e CNC Controls window (see Figure 10.4). _I",,,,

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Begin movin g the X '- and y - axes of yo ur machin e an d no te t he x in the plot w indow. The x indi cat es w here on the tab le the center of t he cutting to ol or pen is located . The z positi on is ind icated by th e ima ge of a cu tti ng tool t hat rais es and lowe rs as yo u jog th e ax is. You w ant your machin e' s x - and y-axes to move in the same di recti on as th e x in th e pl ot window and your z-axis to move up and dow n as the tool image (see Figure 10.5). If you find tha t the ma chin e is movin g in the oppos ite direction, reverse the o rder of the motor wires connected to your driver board. To dete rmin e th e exact size of th e machine's working ar ea, move each axis to its home positi on and zero out that posi tio n in th e CNC Contro ls wi ndow. Now move each axi s in turn to th e end of- t rave l sw itc h. T he length of each ax is w ill be displayed in th e co rres po nd ing distan ce-traveled box . You may not wa nt to hit yo ur limit sw itch es every time yo u hom e t he machine; in this case, set th e zero pos iti o n 1/ 4-inch before t he hom e position limit sw itc h. You can set hom e or th e zero pos itio n any w here yo u pre-

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ACME Profiler ACME Profiler-Coyo te Edit ion , Version 6.0 .0.0. is soft ware t hat is able to gener ate a G-code program that w ill carve materi al by rais ing and low er ing the z- ax ts as the x- and y -a xes are movi ng (see Figu re 10.26). KCam will suppo rt a more three- dimensi onal cutting pat h than our previous examples, but only if G- code is generat ed w ith a different program like the ACME Profiler6 . You can fin d it on the Internet at the Simtel software repositor y. The page w here yo u can download the program is www.simte l.net/ pub/pd/6049 1.htm l. It comes in a registere d version for $20 U.S., or the shareware versio n (w it h so me limitat ions) is free. This software is published by Science Speciali sts, Inc. and their Web site address is w ww2 .fwLco m/ N kimble/ scispec /scispec. htm. Profiler is a straightfo rwa rd prog ram to learn and use. It look s at th e gray scale of a bitmap image and generates the cutt ing path by assigni ng t he maxim um depth yo u in pu t to the

239

CNC Robot ics

Figure 10.26 ACME Profiler6 .

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darkest areas. w ith the cut depth dim in ishing as it moves to w hite. An y jpeg or bmp ima ge file w ill work. but gray-s cal e images will take less time to load and process. W hen creating a grap hi c to open in Profiler, thin k abo ut depth of cut as shades of grey. then expo rt it as a bmp (Wi ndows bitmap) (see Fig ure 10.2 7).

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Load the bm p file in to Profiler by cl icki ng Load Picture fro m th e File dropdow n menu. Set th e number of overl app ing passes you wa nt using t he two slid ing button s at the low er left of th e screen. In di cate w hether you want th e too l pat hs to cut o n t he x-axis or y-ax is, or both. You can have Prof iler offset you r G-code to compensa te fo r th e tool yo u are using. Tell Profi ler the size of t he area th at you wish to mi ll. Set t he depth of cut yo u want to make and the cutter diameter. The Feed and Speed op tions can be disregarded. W hen finished. click the Make NC button. I used a 1/2 -inch cutter d ia mete r for t his test to keep t he lin es of G-code to a minimum . See the resul t in Figure 10.28.

Fig ure 10.28 ACM E Profiler6 generates G-code.

Ope n t he File d ropdown menu and chose th e Save CNC button. name you r fil e w it h a .GC extens io n so that KCam has no tro uble recog nizing it. To use t his file in KCam. ope n the File dropdown menu and click the Open G-Code File button . locate your file and select it . then click Open. Fig u re 10. 29 dep icts how the file profiler6.gc looks fro m t he top. An isomet ric vi ew of the plot is shown in Figu re 10.30 .

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I moved the p rofile dow n about 1/ 16 inch at a time because I didn' t want to stall my homemade lathe. I used a V groove rou ter bit to mill the wood because it w as sharp and for no other reason. You can see the CNC mac hine mi ll ing wood on t he lath e in Figure 12.38 . Figure 12.38 Lathe turning wood under router.

The fi nished pr oduct is shown in Figure 12.39. Figure 12.39 Finished turning.

I coul d p roba bly write an ent i re book on how to use this machine but a chap ter will have to suff ice. I suspec t t hat those w ho build a Workshop Bot for the m selves w il l find hundreds of uses, and enjoy inventing new ways to use their machines every day.

292

Sources of Material Electronic Components L297/L298 Integrated Circuits Manufactured by STMicroelectronics htt p:/ / us.Sl.com / The followi ng list of d istribu tor s co mes d irectly from th e STMicroelectronics Web s ite. They have distributors in a lmost every country on this plan et so I've only listed a few for Canada and the United Sta tes . Visit their site to find the dis tribu to r neares t you.

CANADA Arrow http:/ /www.arrow.com Phone: 613-271-8200 Fax: 613- 271-8 203 Phone: 905- 670- 7769 Fax: 905- 670-7 781 293

CNC Robotics

AVNET

http: / /a vnet.co m Phone : 613-22 6- 1700 Fa x: 613- 226 - 1184 Pho ne: 905 - 8 12- 4400 Fax: 905- 8 12- 44 58 Future Electronics htt p :/ / ww w.fu tu reelect ron ics .com Phone: 905-6 12-9200 Fax: 905-6 12- 9185 Phone : 6 13-7 2 7- 180 0 Fax: 613- 727- 9819 Pioneer Standard http:/ /www.pi on eerstandard.com Phone : 613 -22 6 - 8840 Fax: 613 -226-635 2 Pho ne : 905 -405-8 300 Fax: 905 - 405-642 3 Pho ne : 519- 6 72 -46 66 Richardson Electronics http :/ / www.rell. com Pho ne : 5 14-9 39- 9640

UNITED STATES, CALIFORNIA Arrow Intern et : www.ar row.co m Pho ne : 619- 565- 4800 Fax: 6 19-565-295 9 Pho ne: 818 -880- 9686 Fax: 8 18-880-46 87

294

Sources of Material

Phone: 949 -587-0404 Fax : 949-454-4 206 AVN ET In te rn et: avnet .com Phone: 81 8-59 4-0 40 4 Fax: 858 -385 - 7500 Pho ne: 949-789-4100

Future Electronics In t ernet: www .futureel ectron ics.com Pho ne : 949 - 453- 1515 Fax: 949-453 - 1226 Phone: 6 19-625 -2800 Fax: 619 - 625 -2 8 10

M o user Electronics Internet: w w w .m ouse r.co m/ stm icro Pho ne : 800-34 6-68 73 Fax : 619-449-6041

NU Horizon s Electroni cs http :/ / w w w .n uh ori zon s.com Phone: 949 -470- 1011 Fax: 949-470 - 1104 Phon e: 6 19-576-0088 Fax: 6 19- 576-0990 Phone : 80 5 -3 70- 151 5 Fax : 80 5 -3 70-15 2 5

Pi o n eer Standard http:/ / w w w .p ion eerstand ard .co m Phone: 949 - 753-50 90 Fax: 949- 753 -5 074

295

CNC Robotics

Pho ne: 61 9-5 14- 7700 Fax: 61 9-5 14- 7799 Phon e: 818-865- 5800 Fax: 81 8- 86 5- 5814 Richardson Electronics htt p:/ / w w w.rell.com Pho ne: 818-594-5600 Fax: 818-594-5650 Phone: 909 -600-0030 Fax: 909 -600-0064

Lineal Motion The compani es listed manufactu re compon ent s used to ach ieve lineal motion like bearings and guide rails or acme and ba ll screw s. Although 1 used INA bearings and guid e rails fo r my machin e, yo u can use w hichever prod uct you w an t. T hi s li st is sho rt and doe sn't inclu de every manufacturer of these products. You wi ll find that mos t of th e companies on this li st ar e repre sented all over the world . Canadian Bearings is my local so urce for li neal motion compo nents; they carry man y of t he parts produced by the man ufacturers o n th e list.

Distributor Canadian Bearings Ltd . 500 Tri llium Drive Kitche ner, Ontario Canada N2R 1A 7 Tel: 519- 748- 5500 Fax: 519-748-5040 Toll Free: 1-800- 265- 820 6 After Hou rs: 51 9-5 75-2705 ht tp:/ / w w w.canadianbearings.com/

2 96

Sources of Material

Manufacturers Bishop- Wisecarver Co rporation 2 104 Marti n Wa y Pittsburg, CA 94 565-502 7 Telephone: 925 - 439 -82 72 Toll Free: 888- 58 0- 8272 FAX: 925 -439-5931 http:/ / w ww.bwc.com /ht m l/inde x .htm l IN A Canada, I nc. 2871 Plym outh Drive Oakvill e, Ont ario Cana da L6H 5S5 Tel.: 905 -8 29 -27 50 Fax: 905 -829- 2563 ht tp :/ / w w w.ina.co m/ INA USA Corp o rat ion 308 Springhi ll Far m Road Fort M ill , SC 2971 5 Tel. : 803 -548-8 500 Fax: 803 -548 - 8599 http:/ / w w w .ina.com / IN A Linea r Tec hnik A Di vision of IN A USA CORPORATION 3650 D Cent re D rive Fort M ill , SC 29 71 5 Tel. : 803 - 802-05 t I Fax: 80 3-802-0636 http:/ / w w w. ina .com /

297

CNC Robotics

NSK Amer icas Head Office 4200 Goss Road Ann Arbor, MI 48 105 Tel: 734 -913-7500 htt p :/ / w w w .nsk .co m/ NSK Canada Toronto/Head Office 5585 McAdam Road Mississauga , Ontario Canada L4Z 1N4 Tel: 905 -890-0740 Fax: 905-890-0434 SKF AB SKF, SE-4 15 50 G6tebo rg, Sweden Ho rnsgat an 1 Tel: + 46 -31-337- 10-00 Fax: + 46 -31-337-28-32 http:/ /www.skf.com SKF Canada Limited 40 Exec utive Court Scarboro ugh, Ontario Canada M IS 4N4 Tel: 416-299 - 1220 Fax: 4 16-292-0399 http:/ /www.skf.ca SKF USA Inc. 11 11 Adams Avenue Norristown, PA 19403 -2403 Tel: 610-630-2800 Fax: 610-630-2801 http: / /www.skfusa.co m

298

Sources of Material

SKF Motion Technologies 1530 Vall ey Center Pa rkway Suite 180 Beth lehem, PA 18017 Tel: 800-54 1-3 624 Fax: 610- 86 1-4811 http:/ /ww w.linearmotion.skf.com/ THK Canada 130 M at heson East. Unit I M ississauga, Onta rio Cana da L4Z 1Y6 Tel: 905 -7 12-2 922 Fax: 905 - 712-2925 http :/ / WWW.lh k.co m/ THK Am er ica, Inc. Head Offi ce 200 E. Commerce D rive Schaumburg. IL 60 173 Tel: 847 -3 10- 1111 Fax : 84 7- 310-1182 http:/ /ww w.thk.com / Thomson Industries, Inc. Corporate Headq uarters 2 Cha nnel Drive Port Was hington , NY 11 050 ht tp :/ / w w w.th om sonin d.com /d efaul t.htm USA. Canada, o r M exico Phon e 1-800-554 - 8466 Fax 1-51 6-8 83 - 903 9 Europe Phone 44 - 127 1-334-5 00 Fax 44- 1271-334 -502 29 9

CNC Robot ics

UK Phone 0800- 975 -1000 Fax 0800-975-1001 Fra nce Pho ne 0800- 90-5 721 Fax 0800-91 - 63 15 Germany Phon e 0800-1- 816- 553 Fax 0800- 1-8 16- 55 2 Elsewhere Pho ne 1- 516- 883- 8000 Fax 1- 51 6-8 83- 71 09

Stepper Motors Princess Auto P.O. Box 1005 W innipeg. Manitoba Cana da R3C 2W7 Ph: 20 4-667 -4 630 Fax: 204 -663-7663 In Canada Call Toll Free: 1-800-665-86 85 Fax : 1-800-26 5- 4212 htt p :/ / w w w.p rincessauto.com / Pacific Scientific 4301 Kis hwa ukee Stre et PO Box 106 Rockford. IL 61105 - 0106 Phone 815-226-3100 Fax 8 15- 226-3 148 http:/ / w w w. pacsci .com /

300

Sources of Material

Sanyo De nk i A m er ica, Inc. 468 Ama pola Avenue, Tor rance, CA 90501 Phon e: 310- 783-5400 Fax : 31 0- 212- 6545 http:/ /www.sanyo -den ki.com /

Metal If yo u need a small qua nt it y 01 metal and can't l ind it at a scrap yard , t hen a good pla ce to look is a sto re called Me ta l Supe rmark ets. Th ey have shops in Canada , th e United States, Engla nd , Sco t la nd, a nd Aust ria . Go to t hei r We b si te at http :/ / w w w.metal super markets.co m/ to l ind a loca l store. M etal Supe r ma rk ets (K itchener/Waterl oo) 5 Forwe ll Road, Unit 4 Kitch ener, Ontario Canada N2 B I W 3 Tel: 519- 742-8411 Fax : 519-742 - 9377 Toll Free: 800-742 -8 620

301

Index

Note: Boldface numbers indicate illustrations.

ACM E Profiler, 239 -243 , 240-242 acme screw, 9 Arrow Corporation, 292, 293 AutoCad , 12 AVN ET Cor po ration, 293, 294 bac k EM F, in mot ors, 73-7 4 bea ring guide rail s bear ing holder in, 164- 173, 165-17 3 boll ho les in, 144- 150, 144- 150 X axis, 160 - 164, 161 - 16 4 Z axi s fit an d, 182, 182 beari ngs. linea l mot ion. 8 bipo ia r mo tors, 48, 59, 64 Bishop- W isecarver Corporation. 296 bo lti ng the fra me tog eth er, 138- 140, 138 - 141 ca bi net ry, 281 -292 Canad ian Beari ngs Ltd " 29 5 capacitor installation in driver, 109-110, 110 case enclosure for electronics. 124-1 32, 125. 132 ch anging bi t size , 23 6, 237 chopper co ntro l and ci rc uit, 54- 5 7, 54 , 55, 56, 65, 66- 67 , 67 ci rcl e test fil e, 123- 124 , 124 cle aning stee l, 137, 137 , 138 cl ean ing the pr inted circ uit board , 82-84 , 83, 84 cl ock pulse do ub ler, L297, 59

303

CNC Robotics

CNC controls setting, 11 7, 11 7, 120, 120 ,218-219, 218, 219 computer connection driver and interface board, 118-120, 118, 119 interface board between motors and. 13-15 . 13 interface board to limit switches. 19- 21. 20 conti nuity checking . 107 contro ller software, Ke arn, 2 15-2 19 controllers. motor, ST M icroelectronics manual on (Seealso L29 7; L298 ). 22-75 CorelD raw, I I, 12, 223 -239 , 223 exporting fil es to KCam fro m, 226 , 22 6 , 227, 22 8 KCam use of, 22 4, 225 , 22 6 layout options for, page size, shape . etc., 224, 225 offset t ing G code to cente r the project, 238, 238, 239 texttes t.plt file in, 233 , 234 , 234 vecto r grap hics V5. ra ster gra phics in , 23 8- 239 cost of CNC machines. 1- 2 cutting depth settings, 258 cutting steel , t 36, 136 cutting the printed circuit board. 82 -84 . 83 . 84 Data Exchange Fil e ISee also DXF files) , 22 3 design, 1- 12 acme screw in. 9 dimensions in. 9- 10 front view, JJ ganl ry sty le in, 2 lineal motion in, 4-8 motor drivers, 9 motors for. 2-4 , 3 side view, 10 software selection . 10 -1 2 dimensions of machine, 9- 10 doo rs, 281- 282, 281, 28 2 do vetail jo ints, 283-286, 283 , 284 , 28 5, 286 Oremel tool engraving with, 27 1- 27 4, 271-2 73 holder for , 252 - 257 , 252 -2 5 7 dr illing holes in PCB, 100-101 , 100, 101, 10 2 drills, 100, 100 driver, motor, 9. 15- 19. 17. 99 - 112 bottom ar tw or k for , 79-80, 79 cables fo r, 128, 129 capacitor install ation in. 10 9-110, 110 component placement and installati on in. 10 4-108 , 105, 106 continui ty checking in. 107 dr ill ing hol es in , 100-1 01, 100, 101 , 102 finis hed product, 112 head er s for, 108- J09, 109 heat sink for , I I I, III

304

Inde x

driver, motor (continued) interface board connection to. 11 8- 120 , 118, 119 inte rfa ce boar d for, 111 - 112, 112 L298 ins talla tion in, 109, 109 leads in, 108 materials and tools for, 99 . 100 mo therboa rd mounting of , 126, 126 power supply for, 11 8 sold er ing in, 101, 103, 103 stat ic electricity protection in, 104, 104 testing, 113- 132 top of driver boa rd, 80 , 80 w iri ng , 110- 111, III DXF file s, 12, 219, 22 2-22 3 electronics, 13-75 case enclosure for, 124 - 132, 125, 13 2 in terfa ce bo ard , 19- 21 , 20 interface boa rds, stepper motor dri ver and comp uter. 13- 15 , 13 source s, 29 3-296 stepper moto r driver circuit . 15-19 . 17 engravlng Drcm el tool for, 271 -2 74, 271-2 73 engra ving tool fo r, 268 - 271, 268 - 27 1 Mas ter Craf t ro tary tool for, 274-277 , 274-277 etch in g process in PCB, 93-97, 93, 95, 96 Exell on fil es, 2 19

fan, 125, 128- 129 file format s, in programming, 12 frame, 133- 151 asse mbly of, 141 -14 4, 141, 142, 143 bearing rail supp ort bolt ho les in , 144-150, t 44-1 50 bolting together, 138- 140, 138- 14 1 clean ing, 137, 13 7, 138 cutt ing stee l for, 136, 136 dimensions of. 133- 134, 13 4 pa in tin g, 151 squa rin g and levelin g of, 141 -i 44, 141 tools and materia ls for, 122- 125 we ldi ng together, 143- 144 , 143 front view of CNC machine, II Future Electron ics. 293, 29 4 G code , i i, 219 ga nt ry , 2, 153-160, 154 bear ing ho lde r in , 164- 173, t 65 -1 73 bol t ho le loc ations in, 157 - 158, 158, 159 mounting and access hol es on upri gh ts, 156, 156, 157

305

CNC Rob otic s

gant ry (continued) spanning bea ms for. 155-1 56. 155. 156 tools and materia ls for, 153 upr ights and feet fo r. 155. 155. 159-1 60. 159 . 160 X ax is in . 160 - 164. 161-16 4 Gerber fil es. 219 glass etc hing. 26 6- 26 7. 266. 267 guide rail s. 7. 7. 8 half - step sequence , in motor, 52 , 5 2 heat sink for dr iver. 111, III Hew lett Packard Graphics Language (Sec also HPGL files) . 222 HPGL fil es. 12. 21 9. 222- 223 import file creation for Ke arn, 22 2-223 INA Inc.• 296 in ter face board. 19- 21 . 20 artwork for, 80, 8 1 cables for. 128 . 129 dr iver board connection to. 118-120 , 11 8 , 11 9 motherboard mounting of . 127. 12 7 stepper motor d river and computer. 13 - 15. 13

joint s. cabinetry. 283-2 86. 283. 284 . 285 . 286 KCam and programm ing . 11- 12. 12. 13 ACME Profil er and . 239-243. 24 0-242 AutoCad in, 12

changing bi t siz e and . 23 6. 23 7 CNC con trol selling in. 2 18-2 19. 218 . 2 19 CNC Controll er soft w are for. 215- 219 converting text to curves in. 23 7, 237 Corel Dra w and. II. 12. 22 3-2 39 . 223 cutti ng depth sett ings in , 25 8 dow nloading cop y of. 11 3- 11 4 file fo rmats in . 12.219- 222 G code an d com mands fo r. 11 . 21 9- 221 impo rt file creati on for, 222 - 223 insta ll at ion of. II 3. 2 15 la thecore j .plt fil e. 28 7- 291 li netest. plt file in. 228 -230. 230 Ii netest2 .p lt fil e in . 231 - 232. 233 M code and commands for, II, 220-222 machine setup file for. 258 offsetting G cod e to cente r the project. 238. 238. 239 openi ng. 21 5 port assignm ent in, 216, 217 shapes.plt file fo r. 261-262. 26 1. 262 softwa re selectio n, 10-1 2

306

Index

Kearn and programming (con tinued) system timing in , 2 17, 217 Table Setup w indow in, 215, 216 testt exl. plt file for, 260 , 260, 26 1 textt est.plt fi le in , 233 , 234, 234 tool size setting in, 234, 235 , 236 user define d M code s for, 22 2

Kell y Ware (See also KCam) , 113 L297 stepper mo tor con tr oller, IS , 18- 19,22- 75,22, 23 ,46 a version of (L297A), 57-58 , 58 advantages of, 46 -47 ap pli cal ion for, 29 bipola r ste ppe r moto r a nd , 5 9

block diagra m of, 23 circui t op eration in, 2S clock pulse doubler In, 59 DIP packa ge mechanical data for, 30- 31, 30, 3 1 electrical characteristics of, 27- 28, 28 half step mod e i n, 26 , 26 L293E vs. 47 normal drive mode in, 26. 26

phase sequence in. 26 pin co nnec tions for. 23 , 62

pin function chart for. 24- 25 pin functions for, 6 1 sources for, 29 2 synchroni za tion in. 29 un ipo lar motors and , 5 9 w ave drive mode in . 2 7, 2 7 L298 H br idge IC, I S, 18-19, 33- 75, 33 a pplication informat ion in. 39 bidirectiona l control in. 38 . 40 block diagram of , 33 dimensio n data for. 42, 4 2 electr ica l cha racteristics of, 35 -3 6 installing in dr iver, 10 9. 109 ma xim um rat ings tor, 34 m uiti watt IS H, 43 , 43 multiwatt 15V, 42, 4 2 PCB layout for, 4 1 pin co nnec tions for. 34 p in funct ions for, 35 PowerS020 , 44, 44 satu ration voltage in, 36 sink current in, 3 8 sources for, 29 2 sw itching times in, 36 , 3 7 the rm a l data on, 34

307

CNC Robot ics

lath e, 286-292 , 287 lathecore3.plt file, 28 7-29 1 lim it sw itch installa t ion, 206-21 4, 207 , 208 interface board to comp uter. 19-2 1, 20 lineal motion . 4-8 bea rings in, 8 guide rails in. 7. 7. 8 suppliers of mat er ial for, 296 -300 TV gli de tray assembl y i n, 8 Iinetest.plt file , 22 8-230 , 230 linetest2.p lt file in, 231 -2 3 2, 233 load curre nt regula tion. motor, 53-54. 5 4

losses. motors, 68 M co de, I I , 220 -222 machin e setup file. Ke arn. 258 Mas ter Craft rotary tool engraving, 274- 277 . 2 74 - 2 77 materia ls, sources, 29 3-301 M D F as table board, 25 7, 258 mecha nica l engrav ing tool, engr avings. 268 - 2 71, 268-2 71 Me tal Supe rmarkets, 300 metal , suppliers of , 300 motor mo unts, 190 , 19 0 , 191 , 19 2 motors, 2 - 4 , 3 , 14 back EM F and, 73-74 bipola r, 48, 59 , 64 cable conne ction s to, 130 - 131, 130 , 13 1 c hoppe r co nt ro l fo r, 54 - 57, 54 , 55, 56, 65, 66 -67, 67, 70 - 73, 71 controlle rs for, ST M icroelectronics manua l on (Seea/so L29 7; L29 8) . 22-75 dr ive top ology select io n fo r, 64 -6 5, 64 dri ver for, 9, 15- 19, 17 flexi ble shaft co upling for, 198, 198 half step dr ive, 49 , 52, 52 installation of. 18 9-2 14 inte rface board to comp ute r and. 13- 15. 13 L29 7 step per mo to r co ntro ller Ie for (See also L2971, I S, 18- 19, 22 -7 5, 22, 23 L298 H bri dge IC (See also L298), IS , 18- 19, 33 -75, 33 lead screw centering and mounting. 193- 196. 193-196. 19 7 limit sw itch insta lla tio n fo r, 206- 21 4, 20 7. 20 8 load current regulat ion in, 53-54 , 54 losses in, 68 minim um current in. 68 , 6 9 mounts for. 190. 190 . 191. 19 2 noise and , 70-73 , 71. 72, 73 peak detect current in, 68. 69 phase sequence generation in, SO-5 3. 51. 5 2. 53 power dissipat ion in bridge Ie in. 68 . 71

308

Ind ex

motors (continued) p ow er supply for . 4. 15 problem s and soluti ons for . 64-75 ripple current in. 68 selection of, unipo lar

Y5.

bipol a r, 64

sources for used/ second-hand, 4 stepper motors, 4 8 stuck condition in. 74 suppliers for. 300- 30 1 tools and materia ls for installation of. 189 two pha se dri ve in . 49 . 52. 52 un ipolar. 48 . 50 . 60. 64. 66 variabl e reluctanc e, 50, SO wa ve dri ve state sequence in, 53 . 53 wind ing current in. 69 , 70 w iri ng diagram for, S X axi s and . 190- 199. 193 X axi s limit setti ng for. 208-209 . 208. 209 Y axis and . 199- 203 . 199- 203 Y axi s limi t sett ing for . 209 -210. 210 Z axi s and. 203-2 06 . 20 4- 206 Z axi s li mit setting for. 2 11-2i 4. 211- 2 14 Mo user Electron ics. 294

noise, in motors, 70-73, 7 1, 7 2, 73 NSK Inc.• 297 N U Horizons Electronics, 294 N uA rc Mod el SST 1418 hori zontal camera. exp loded view. 6 , 7

Pacifi c Scient ific , i 3. 15.299 pain ting the fram e. 151 peak detect current. in motors, 68, 69 pen hol der, 246 -252 . 24 6- 252 phase sequence gene ration in motors, 50-5 3, 5 1, 52 . 5 3 Pioneer Standa rd. 293 . 295-296 plotter. 263-2 68, 26 4 , 265 port assignment. 11 5. 116, 11 6 . 118, 21 6.2 17 power supp lies , 4, 15. 11 8, 129 connecting. 128 , 12 8 . connector strips for. 127, 12 7 fa n connection to, 128 -129 wi ring diagram for motors, S Princess Auto, 13, 299 pr inted circui t board construction. 7 7- 97 aligning the artwork for, 85 , 8 5. 8 6 art w ork for, 78-8 2 bott om of dri ver board, 79-80. 79 cleani ng, 82-84 cut ting , 82- 84

309

CNC Robot ics

printed circuit board construction (continued) drilli ng holes in , 100- 101 , 100, 101, 102 etching process in, 93-9 7, 93, 94, 9 5, 96 interface board, 80 . 81 ma te r ials and too ls for, 77, 78 photo resist process in. 78 print ing th e ar two r k for, 80-82 soldering in, 101, 103, 103 static electricity protection in, 104, 104 tinning in, 96. 9 7 toner transfer process in , 85-92 , 87 , 88 , 89, 90, 91,92 top of driver board, 80, 80 printe rs, for PCB construction. 80-82 pro gramm in g (See KCam and programming) raster graphics, 238 - 239 read y rod, 9 Richardson Electro nics. 293 . 295 ripp le current. in motors. 68 ro tar y tool eng raving (M aster Craft), 27 4-2 77, 274 - 277 route r holder fo r, 252 -25 7, 252-25 7 ro uting with , 278 -292, 278-292 Sanyo Den ki, 16, 300 shapes.pit file , 26 1- 262, 261, 262 side view of CNC machine. 10 sign makin g. 278-28 1, 278 -280 SKF Inc., 298-2 99 software setup and driver testing. 10- 12, 113-13 2 case enclo sure for electronics and , 124 - 132 , 12 5 , 132 circle test ti le in, 123 - 124, 124 CNC co ntrols sett ing in , 117, 117, 120, 120 Kea rn installat ion for. 11 3-11 4 materials nceded for. 113 port assignment in. 115. 11 6 , 116. 11 8 Square-gc. txt test fi le fo r, 121, 122 steps setti ng

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