Project Book

Design &Manufacturing of

PCB Milling Machine

Under supervision of

Dr. Mahmoud Abdelnaby Sayed Asst.prof at Qena Faculty of Engineering

South Valley University

TEAM MEMBERS

1. Abd Elrahman Hamam

2. Ali Ahmed Mohammed

3. Hassan Ayoub Hassan

4. Mohammed Ahmed Anwar

5. Mohammed Ahmed Alsayed

6. Mohammed Ahmed Khodari

7. Mohammed Foud Alsayed

8. Mohammed Soliman Mohamed

9. Mahmoud Mohammed Abdel latif

10. Ziad Khaled Abd Almaged

Aswan, Egypt

June, 2012

I

Acknowledgment

It is impossible to remember or acknowledge all the

people who have helped us in our education at Faculty

of Energy Engineering .Gave us good theoretical

training .all people we have dealt within our project have

helped us to achieve our goals and launch our project.

We would also like to express our gratitude and

appreciation to Dr. Mahmoud Abdelnaby for all the help and guidance he provided throughout graduation

year, and to the other members of our instructors.

We would like to thank our families, especially our

parents, for their encouragement, patience, and assistance

over the years. We are forever indebted to our parents,

who have always kept us in their prayers.

Team members would like to dedicate this project

to January 25 Martyrs.

II

Abstract

As we approached our final year, we have a lot of ideas on how

our project would look like, after a lot of searching us finally

gathered on this one. We have designed and manufactured a

working machine that solves a lot of problems and take us a step

forward in the technology race.

This project is about mailing machine that is capable of

manufacturing and producing printed circuit boards. From A to

Z, we will discuss every part in this project field, designing the

machine, and collecting its parts, passing with searching for data

on every possible way.

Than moving to electrical field, on making the driving system

and choosing suitable motor type between a lot of selections.

After that, paying attention to the programming field and

making the right combination of series programs, finally testing

our machine and having its characteristics evaluated and

recording all this away.

III

Contents Chapter1 Introduction Page no. 1.1 Introduction 1

1.1.1 CNC application 1

1.2 Printed circuit board (PCB) 1

1.2.1 PCB definition 1

1.2.2 History of PCB 2

1.3 Manufacturing PCB using CNC 3

1.3.1 Field of the Invention 3

1.3.2 Description of the Prior Art 4

1.4 Objectives 5

1.5 Project contents 5

Chapter 2: Stepper Motor and Drive Circuit

2.1 Introduction 7

2.2 Types of PCB motors 7

2.2.1 Dc motors 7

2.2.2 Stepper motors 9

2.2.2.1 Principle operation of stepper motor 9

2.2.2.2 Driving modes 9

2.2.2.3 Types of stepper motors 9

2.3 DC Servo Motors VS. Stepper Motors 14

2.4 Stepper Motor Driver Circuit 17

2.4.1 Brief explanation of the driver circuit 18

2.4.1.1 Brief list of the circuit components 18

2.4.1.2 Operation of drive 20

2.4.2 The interface board 21

2.4.2.1 Brief list of interface board component 21

2.4.2.2 Operation of inter face circuit 22

2.5 Limit switches 23

2.5.1 Definition 23

2.5.2 Limit Switch operation 23

2.5.3 Limit Switch circuit 24

2.6 The spindle relay circuit 24

2.7 Emergency stop 25

Chapter 3 Machine design

3.1 Introduction 26

3.2 Mechanical Design 27

3.2.1 Choosing anatomy of motion and design 27

3.2.2 Our machine design 29

3.3 linear motion system and bearings 32

3.3.1 Types of bearings 32

3.3.2 Used bearing type in our PCB machine 34

3.4 power screw 35

IV

3.4.1 Introduction 35

3.4.2 Machine calculation 36

3.5 Manufacturing material 37

3.5.1 Suitable material for PCB machine 37

3.6 Spindle and component box fixing 39

3.6.1 The router spindle 39

3.6.2 Components box 40

3.7 Fixing the copper board (PCB) 41

3.7.1 Description 41

3.7.2 Available methods to fix the PCB 41

3.8 Fixing stepper motor 43

Chapter 4: programming (Mach 3)

4.1 Introduction 44

4.2 Eagle, PCB G-code and control software 44

4.3 The Mach3 control software 45

4.4 Downloading and Installing Mach3 45

4.5 Parallel port 46

4.5.1 Function of parallel port 46

4.5.2 Parallel port installing 47

4.6 Configuring Mach3 47

4.6.1 Motor Outputs 47

4.6.2 Limit switches 48

4.6.3 Spindle 49

4.6.4 Emergency Stop 50

4.6.5 Motor tuning and setup 50

4.7 Testing the machine 51

Chapter 5: experimental results & conclusions

5.1 Why this project 53

5.2 Conclusions 54

5.3 Budget 55

5.4 Experimental results 56

5.5 Project in 4 steps 57 5.6 Example of machine product 57

5.7 Problems of our machine 58 5.8 Future work and improvements 60

References 61

Appendix

V

List of figure

Figure 1.1 The translucent paper and the board 2

Figure 1.2 PCB manufactured with Acid 3

Figure 1.3 The photo-resist board 3

Figure 2.1 Construction of permanent magnet DC motor 7

Figure 2.2 Construction of dc servo motor 8

Figure 2.3 DC servo motor 8

Figure 2.4 Stepper motor 9

Figure 2.5 Basic design of stepper motor 10

Figure 2.6 Single-coil excitation 10

Figure 2.7 Full step drives 10

Figure 2.8 Half stepping 11

Figure 2.9 Different shapes of signals 11

Figure 2.10 Basic unipolar stepper motor 12

Figure 2.11 Conceptual model of unipolar stepper motor 13

Figure 2.12 Basic bipolar and conceptual model of bipolar stepper motor 13

Figure 2.13 Stepper motor driver circuit drawn with proteus program 19

Figure 2.14 Interface circuit diagram using proteus 22

Figure 2.15 Limit switch construction 23

Figure 2.16 Limit switch circuit 24

Figure 2.17 Spindle switch circuit 24

Figure 2.18 Emargancy stop 25

Figure 3.1 General model of the PCB machine 26

VI

Figure 3.2Fixed table type 27

Figure 3.3 Fixed table with power screw in the middle 28

Figure 3.4 Fixed table with sliding tower 28

Figure 3.5 Movable table 28

Figure 3.6 Sketch for X direction module 29

Figure 3.7 Sketch for Y& Z-Direction module 29

Figure 3.8 General view for X & Y & Z-axis module 29

Figure 3.9 Show parts mentioned in table (3.1) 31

Figure 3.10 Drawing show the individual three axis sketches on AutoCAD. 31

Figure 3.11 Various shapes of the sliding rods bearing. 32

Figure 3.12 linear guide. 33

Figure 3.13 The internal component of ball bearings 33

Figure 3.14 Single-Row Deep-Groove ball bearing 34

Figure 3.15 The bearings of our machine. 34

Figure 3.16 Illustrating calculation of the power screw. 35

Figure 3.17 Power screw diagram 36

Figure 3.18 PCB machine made of MDF 37

Figure 3.19 PCB machines made of plastic and PVC 38

Figure 3.20 PCB machine made of aluminum 38

Figure 3.21 The spindle motor. 39

Figure 3.22 View of the component box 40

Figure 3.23 sketch of the component box 40

Figure 3.24 PCB fixed with metal stripe angle 41

Figure 3.25 PCB fixed with nails. 41

Figure 3.26 PCB fixed with plastic stripes 42

Figure 3.27 PCB fixed with four nails on flat surface 42

Figure 3.28 Stepper Motor before and after fixing 43

VII

Figure 4.1 Main screen of PCB-G-code 44

Figure 4.2 The main screen of Mach3 45

Figure 4.3 Installing Mach3 46

Figure 4.4 Parallel port pins 46

Figure 4.5 Parallel port installing 47

Figure 4.6 Verify that the three axes are all enabled 48

Figure 4.7 Limit switches Configuring 48

Figure 4.8 Spindle setup 49

Figure 4.9 Spindle Configuring 49

Figure 4.10 Emergency Stop Configuring 50

Figure 4.11 Single screen is used to easily configure all three motor settings 50

Figure 4.12 Test PCB machine using the MDI tab 51

Figure 4.13 use the input field to manually enter G-Code for testing 52

Figure5.1 Engineering science implementation in PCB machine 53

Figure 5.2 The driver circuit (front view) 56

Figure 5.3 The Driver circuit (back view) 56

Figure 5.4 Schematic design of our example 58

Figure 5.4 Board design of our example 58

Figure 5.6 The machine product 59

VIII

List of Tables Table 2.1 Obtain compare between DC servo motor and stepper motor 15

Table 2.2 List the motor used in the machine 18

Table 2.3 Show the drive circuit componant 18

Table 2.4 Obtain brief list of interface board componant 21

Table 3.1 Parts of mechanical design 30

Table 3.2 Spindle data 39

Table3.3 Dimensions of component box 40

Table 5.1 Obtain all cost of our project 55

Table 5.2 Obtain motor currents 56

Ch.1 Introduction EDT 2012

1

Chapter (1)

Introduction

1.1 Introduction

Computer numerical control (CNC) is one in which the function and

motions of a machine tool are controlled by the means of a prepared

program containing coded alphanumeric data.

CNC can control motions of work piece or tool, the input parameters

such as feed, depth of cut, speed, and the function such as turning

spindle on-off and Turing coolant on-off.

CNC application 11.1.

The application of CNC includes both machine tool as well as non-machine

tool areas. In the machines tool category, CNC is widely used for lathe,

drill press, milling machine, grinding unit, laser, sheet metal press working

machine, tube bending machine etc. In the non-machine tool category,

CNC applications include welding machines (arc and resistance),

coordinate measuring machine, electronic assembly, tape laying and

filament winding machines for composites etc.

The function of this project is to use the CNC application in making printed

circuit board (PCB).

1.2 Printed Circuit Board (PCB)

1.2.1 PCB definition

A PCB is a printed circuit board, also known as a printed wiring board. It

is used in electronics to build accurate electronic circuits. A PCB serves

two purposes in the construction of an electronic device; it is a place to

mount the components and it provides the means of electrical connection

between the components.


2

1.2.2 History of PCB

Back in the pre-computed aided design ( CAD) days, PCBs were

designed and laid out by hand. A PCB starts out as a thin, non-

conducting sheet of material. The most common material used is a

glass fiber epoxy laminate material. A thin layer of copper is then

chemically deposited on each side of this material, which allows

double layer circuit design.

The next step is to "print" the connection diagram onto the PCB.

The connection diagram is the wiring required to connect the

components. In the very early days of electronics, these connections

were in fact done with wires. This is the reason PCBs are also

sometimes referred to as printed wiring boards. The "printing" is

usually done by photographically transferring the image to the PCB.

This image is "printed" with an acid resistant material.

Figure 1.1: The translucent paper and the board.

Then, the PCB is put into an acid bath (Ferric Chloride Acid). The

acid bath removes the copper from the board, excepting the areas

protected by the resistant material ink. This process leaves the

connections or wiring "printed" on the PCB. After that, holes are

drilled in the board to allow the components to be mounted to the

PCB and the PCB itself to be mounted on the case protecting the

electronics. Finally, a protective coating is applied to the board to

prevent corrosion of the copper traces.


3

Figure 1.2: PCB manufactured with Acid.

Also there is the PHOTO-RESIST BOARD which is a piece of glass

reinforces plastic. One of the sides is copper clad and this copper has

a photosensitive coating. When the plastic film is peeled back this

sensitive coating is revealed leaving the desired circuit.

.

Figure1.3: The photo-resist board.

using CNC PCB3 Manufacturing 1.

projectField of the 1.31.

This project relates to a working machine for trial construction of a

printed circuit board (here in after called a PCB) by effecting some kinds

of working, such as making a circuit pattern on a copper-foiled substrate,

making holes in lands, and so on, in accordance with geometrical data

made by a CAD.


4

1.3.2 Description of the prior Art

In order to develop electronic devices and to fabricate such devices that

are small in amount of production and hence not suitable for mass

production, there is an increasing need for constructing PCB substrates

with appropriate electronic circuits on a trial basis, precisely, quickly, and

at a low cost.

However, since trial construction of PCBs needs steps of photographic

Chemical and other treatments, circuit patterns must be made even

for fabricating a small amount of trial PCBs, and most of planners,

designers and other engineers have been compelled to order such work to

specialists.

In order to improve the situation, there has been proposed a PCB working

machine for making a circuit pattern by cutting a copper-foiled substrate

in which a copper layer is provided on an insulating substrate.

More specifically, such PCB working machines are configured such that a

cutting tool is fixed to a spindle moveable in X-axis and Y-axis directions

under a control, and it is moved, in accordance with a predetermined

pattern, on a PCB substrate which is held in place on a work table with a

suction force, to cut the copper layer and the insulating substrate on

the PCB to make a target circuit.

In the working machines having the foregoing construction, after the

cutting tool is fixed to the chuck at the distal end of the spindle, the

cutting edge of the cutting tool is brought into contact with the surface of

the PCB substrate to detect the position of the surface of

the PCB substrate. After that, the spindle is driven to move down by a

necessary amount by a stepping motor for Z-axis movements such that

the cutting edge of the cutting tool cuts into the surface of

the PCB substrate by-a precise depth. That is, the widths of cuts are

controlled in the foregoing process.

This method, however, is likely to cause errors in level of the cutting edge

of the cutting tool relative to the level of the surface of the PCB substrate,

because of a microscopic unevenness of the surface of the PCB substrate

or displacement of the spindle caused by heat. This is a serious problem

in making a circuit pattern with microscopically distant lines.

The aforementioned method also involves a problem such that shavings

may remain on the worked surface. Such shavings, if remaining on the

worked surface, may cause a short-circuit between lines or cut and break

the circuit pattern. In addition, Cutting tools are subject to breakage.

When such breakage occurs during automatic driving of the machine, it

results in defective cuts.

Moreover, the cutting tool is likely to stick to the chuck, and it has been

difficult to automate replacement of the tool with another.


5

1.4 Objectives

It is therefore an object of the project to overcome the problems involved

in the existing PCB manufacturing methods, and these can be

summarized by:

1- Provide a PCB working machine that makes it possible to easily mill. 2- Provide a PCB working machine that has high Speed and high

accuracy.

3- Provide a PCB working machine that is easy and simple to deal with. 4- Provide a PCB working machine that has the ability to produce a

double layer PCB.

5- Provide a PCB working machine that has less operation time than conventional Methods.

1.5 Project contents

The following project contains five chapters that describe the whole work

done in designing, calculating, programming and manufacturing the

machine. Here is quick preview of what are coming.

Chapter 1: Introduction

Chapter 2: Stepper motor and its Driver circuit

In this chapter we will discuss the principal operation of the stepper

motor and its working theory. Also we will have a close look on the

driver circuit of the stepper motor, its operation and the electrical

connections of the electronics parts.

Chapter 3: Machine Design

In this chapter we are going to discuss the mechanical design of the

machine which includes all steps of designing and manufacturing the

body of the machine. Also we will mention the ways to fix, support, and

combine all the mechanical parts, cutting tool, and the stepper motors.

Chapter 4: Programming software

In this chapter we will discuss the program used in controlling the

machine. The function of the program is to design the PCB as schematic,

then converting the schematic file in to the G-code that can be transferred

from the computer to the machine through the parallel port. Also its

operation and cooperating with the stepper motors and the machine are

discussed.


6

Chapter 5: experimental results & conclusions

In the last chapter we are going to discuss the last results of the machine

and the measurements that we have approached and achieved. Also the

conclusion of the whole work and the final product. Finally a few

suggestions on the future improvements.

Ch.2 Stepper Motor and Drive Circuit EDT 2012

6

Chapter (2)

Stepper Motor and Drive Circuit

2.1 Introduction

Motors are the heart of any PCB machine. The size and type of motor can define

a PCB routers precision, speed, and accuracy. There are two primary classes of

motors used on PCB machines, stepper motors and servo motors. This chapter

gives a brief introduction about the stepper motor used in the project. Two types

of stepper motor have been explained. These types are unipolar and bipolar

stepper motors. The operation theory is explained in details of both motors.

2.2 Types of PCB motors

In this section will show primary type of motors used in PCB machine and

feature which lead us to use stepper motors in our machine.

2.2.1 Dc motors

Fig 2.1 shows the construction of a permanent magnet DC motor consisting of a

stator, a rotor, and a commutation mechanism. The stator consists of permanent

magnet, creating a magnetic field in the air gap between rotor and stator. Rotor

has several windings arranged symmetrically around the motor shaft. An electric

current applied to the motor is delivered to individual windings through the

brush-commutation mechanism as shown in the fig 2.1. As the rotor rotates the

polarity of the current flowing to the individual windings is altered. This allows

the rotor to rotate continually.

Figure 2.1: Construction of permanent magnets DC motor.


7

DC servo motor is considered one of the most commonly type of DC motor used

in PCB machine. The servo motor is actually an assembly of four things; a

normal DC motor, a gear reduction unit, a position-sensing device (usually a

potentiometer), and a control circuit as shown in fig 2.2.

Figure 2.2: Construction of dc servo motor.

The function of the servo is to receive a control signal that represents a desired

output position of the servo shaft, and apply power to its DC motor until its

shaft turns to that position. It uses the position-sensing device to determine the

rotational position of the shaft, so it knows which way the motor must turn to

move the shaft to the commanded position. The shaft typically does not rotate

freely round and round like a DC motor, but rather can only turn 200 degrees or

so back and forth.

The servo has a 3 wire connection: power, ground, and control. The power

source must be constantly applied; the servo has its own drive electronics that

draw current from the power that lead to drive the motor.

The control signal is pulse width modulated (PWM), but here the duration of the

positive-going pulse determines the position of the servo shaft.

Figure 2.3: Dc servo motor.


8

2.2.2 Stepper motors

Stepper motors is one of the most important actuators used in devices need high

accuracy such as PCB machines, printers, copy machines,etc.

Stepper motor is an electromagnetic actuator that converts electrical power into

mechanical power. The main difference between them and all the other motors

is the way they revolve. Unlike other motors, stepper motors does not

continuously rotate they rotate in steps. Each step is a fraction of a full circle.

This fraction depends mostly from the mechanical parts of the motor, and from

the driving method. The stepper motors also differs in the way they are powered.

Instead of an AC or a DC voltage, they are driven (usually) with pulses.

Figure 2.4: Stepper motor.

2.2.2.1 Principle operation of stepper motor

The stepper motors consists of a stator and a rotor. The rotor carries a set of

permanent magnets, and the stator has the coils. The very basic design of a

stepper motor would be as follows. There are 4 coils with 90o angle between

each other fixed on the stator as show in fig 2.5. The way that the coils are

interconnected, will finally characterize the type of stepper motor connection. In

the below drawing, the coils are not connected together. The below motor has

90o rotation step. The coils are activated in a cyclic order, one by one. The

rotation direction of the shaft is determined by the order that the coils are

activated. The coils are energized in series, with about 1sec interval. The shaft

rotates 90o each time the next coil is activated.

2.2.2.2 Driving modes

In this section, will explain the various ways that the coils are energized, and the

results on the motors shaft.


01

Figure 2.5: Basic design of stepper motor.

1. Single-Coil Excitation

The first way is called Single-Coil Excitation, and means that only one coil is

energized each time. This method is rarely used, generally when power saving is

necessary. It provides less than half of the nominal torque of the motor; therefore

the motor load cannot be high.

Figure 2.6: Single-coil excitation.

2. Full step drive

The second and most often used method is the Full step drive. According to this

method, the coils are energized in pairs. According to the connection of the coils

(series or parallel) the motor will require double the voltage or double the current

to operate that needs when driving with Single-Coil Excitation. Yet, it produces

100% the nominal torque of the motor.

Figure 2.7: Full step drive.


00

3. Half stepping

This is a very interesting way to achieve double the accuracy of a positioning

system, without changing anything from the hardware. According to this method,

all coil pairs can be energized simultaneously, causing the rotor to rotate half the

way as a normal step. This method can be single-coil or two-coil excitation as

well.

Figure 2.8: Half stepping.

4. Micro stepping

Micro stepping is the most common method to control stepper motors nowadays.

The idea of micro stepping is to power the coils of the motor not with pulses, but

with a waveform similar to a sin waveform. This way, the positioning from one

step to the other is smoother, making the stepper motor suitable to be used for

high accuracy applications such as PCB positioning systems. Also, the stress of

the parts connected on the Motor, as well as the stress on the motor itself is

significantly decreased. With micro stepping, a stepper motor can rotate almost

continuous, like simple DC motors. The waveform that the coils are powered

with is similar to an AC waveform; Digital waveforms can also be used.

Here are some examples

Sin wave signal Digital signal High resolution digital signal

Figure 2.9: Different shapes of signals.


01

The micro stepping method is actually a power supply method, rather than coil

driving methods, therefore the micro stepping can be applied with single-coil

excitation and full step drive.

2.2.2.3 Types of stepper motors

Stepper Motors come in a variety of sizes, and strengths, There are two basic

types of steppers. Bipolar and unipolar. The bipolar stepper has 4 wires. Unipolar

steppers have 5, 6 or 8 wires. In the next sections will discuss the bipolar,

unipolar stepper motors.

1. Unipolar stepper motor

Basic construction of motor

The Unipolar Stepper motor has 2 coils, simple lengths of wound wire. The coils

are identical and are not electrically connected. Each coil has a center tap Wire

coming out from the coil that is midway in length between its two terminals. You

can identify the separate coils by touching the terminal wires together. If the

terminals of a coil are connected, the shaft becomes harder to turn. Because of the

long length of the wound wire. Also you can identify the center tap by measuring

resistance with a suitable ohm-meter. The resistance from a terminal to the center

tap is half the resistance from the two terminals of a coil.

Figure2.10: Basic unipolar stepper motor.

Conceptual Model of unipolar Stepper Motor

With center taps of the windings wired to the positive supply, the terminals of

each winding are grounded, in sequence, to attract the rotor, which is indicated by

the arrow in the picture, this conceptual diagram depicts a 90 degree step per

phase as shown in fig 2.11.

Unipolar Stepper Motor Ratings

Manufacturers rate stepper motors with at least two of the familiar electrical

terms: voltage, current, resistance. When one of these terms is missing it can be

derived using the formula: Voltage = Current x Resistance. If only the current


02

rating is known, the resistance rating can be found by carefully measuring a half

coil (center-tap to either terminal) with an ohmmeter. In the rating nomenclature,

a phase refers to the minimum operational coil, which is a half-coil for unipolar

motors.

Figure2.11: Conceptual model of unipolar stepper motor.

2. Bipolar stepper motor

Bipolar just means there are 2 undivided coils with only 2 wires present for each

phase. So a 2 phase bipolar motor has 4 wires (2 coils). An equivalent unipolar

motor will have the same 4 wires plus 2 or 4 additional wires coming from the

coil center. Most unipolar motors can function as bipolar, but a bipolar motor

cannot function as a unipolar because it lacks the additional wires.

Figure2.12: Basic bipolar and conceptual model of bipolar stepper motor.


03

3. Features of stepper motor

Stepper Motors have several features which distinguish them from AC Motors,

and DC Servo Motors.

Brushless: Steppers are brushless. Motors with contact brushes create

sparks, undesirable in certain environments.

Holding Torque: Steppers have very good low speed and holding torque.

Steppers are usually rated in terms of their holding force (oz/in) and can

even hold a position without power applied, using magnetic 'detent' torque.

Open loop positioning: Perhaps the most valuable and interesting feature of

a stepper is the ability to position the shaft in fine predictable increments,

without need to query the motor as to its position. Steppers can run 'open-

loop' without the need for any kind of encoder to determine the shaft

position.

Load Independent: The rotation speed of a stepper is independent of load,

provided it has sufficient torque to overcome slipping. The higher rpm a

stepper motor is driven, the more torque it needs, so all steppers eventually

poop out at some rpm and start slipping.

2.3 DC Servo Motors VS. Stepper Motors

The following will attempt to justly compare stepper vs. servo motors assuming

the following

-The motors are of equal rated power

-Both motors we are comparing are of same quality

-Servo is equipped with an encoder

-Stepper is not equipped with an encoder

-The driver is assumed to provide the same features excluding feedback.


04

Characteristics Servo Motor (DC Brushed) Stepper Motor

Cost

The cost for a servo motor and servo

motor system is higher than that of a

stepper motor system with equal power

rating.

This feature would have to

go to stepper motors.

Steppers are generally

cheaper than servo motors

that have the same power

rating.

Versatility

Servo motors are very versatile in their

use for automation and CNC

applications.

Stepper motors are also

very versatile in their use

for automation and CNC

applications. Because of

their simplicity stepper

motors may be found on

anything from printers to

clocks.

Reliability

This is a tossup because it depends on

the environment and how well the

motor is protected.

The stepper takes this

category only because it

does not require an

encoder which may fail.

Frame Sizes

Servo motors are available in a wide

variety of frame sizes, from small to

large motors capable of running huge

machines. Many of the motors come in

NEMA standard sized.

Stepper motors do not

have as many size

selections as servo motors

in the large sizes. However

stepper motors may still be

found in a variety of

NEMA frame sizes.

Setup

Complexity

Servo motors require tuning of the

proportionalintegralderivative (PID) closed loop variable circuit to

obtain correct motor function.

Stepper motors are almost

plug-and-play. They

require only the motor

wires to be wired to the

stepper motor driver.

Motor Life

The brushes on servo motors must be

replaced every 2000 hours of

operation. Also encoders may need

replacing.

The bearing on stepper

motors is the only wearing

parts. That gives stepper

motors a slight edge on

life.

Low Speed

High Torque

Servo motors will do fine with low

speed applications given low friction

and the correct gear ratio

Stepper motors provide

most torque at low speed

(RPM).


05

High speed

High Torque

Servo motors maintain their rated

torque to about 90% of their no load

RPM.

Stepper motors lose up to

80% of their maximum

torque at 90% of their

maximum RPM.

Repeatability

Servo motors can have very good

repeatability if setup correctly. The

encoder quality can also play into

repeatability.

Because of the way stepper

motors are constructed and

operate they have very

good repeatability with

little or no tuning required.

Overload

Safety

Servo motors may malfunction if

overloaded mechanically.

Stepper motors are

unlikely to be damages by

mechanical overload.

Power to

Weight/Size

ratio

Servo motors have an excellent power

to weight ratio given their efficiency.

Stepper motors are less

efficient than servo motors

which usually mean a

smaller power to

weight/size ratio.

Efficiency

Servo motors are very efficient.

Yielding 80-90% efficiency given light

loads.

Stepper motors consume a

lot of power given their

output, much of which is

converted to heat. Stepper

motors are usually about

70% efficient but this has

some to do with the

stepper driver.

Flexibility in

motor

resolution

Since the encoder on a servo motor

determines the motor resolution servos

have a wide range of resolutions

available.

Stepper motors usually

have 1.8 or 0.9 degree

resolution. However

thanks to micro-stepping

steppers can obtain higher

resolutions. This is up to

the driver and not the

motor.

Torque to

Inertia Ratio

Servo motors are very capable of

accelerating loads.

Stepper motors are also

capable of accelerating

loads but not as well as

servo motors.

Least Heat

production

Since the current draw of a servo

motor is proportional to the load

applied, heat production is very low.

Stepper motors draw

excess current regardless

of load. The excess power

is dissipated as heat.


06

Reserve Power

and Torque

A servo motor can supply about 200%

of the continuous power for short

periods.

Stepper motors do not

have reserve power.

However stepper motors

can brake very well.

Noise Servo motors produce very little noise.

Stepper motors produce a

slight hum due to the

control process. However a

high quality driver will

decrease the noise level.

Resonance and

Vibration

Servo motors do not vibrate or have

resonance issues.

Stepper motors vibrate

slightly and have some

resonance issues because

of how the stepper motor

operates.

Availability

Servo motors are not as readily

available to the masses as are stepper

motors.

Stepper motors are far

easier to find than quality

servo motors.

Motor

Simplicity

Servo motors are more mechanically

complex due to their internal parts and

the external encoders.

Stepper motors are very

simple in design with no

designed consumable

parts.

Direct Drive

Capability

Servo motors usually require more

gearing ratios due to their high RPM. It

is very rare to see a direct drive servo

motor setup.

Stepper motors will work

fine in direct drive mode.

Many people simple use a

motor couple and attach

the motor shaft directly to

the lead screw or ball

screw.

Power Range

Because servo motors are available in

DC and AC servo motors have a very

wide power availability range.

The power availability

range for stepper motors is

not that of servo.

Table 2.1: Obtain compare between DC servo motor and stepper motor.

The shaded selections in the comparison chart in the previous page are the selected

category winner as designated by" CNCRoutersource.com". It's always up for debate

depending on the motor and usage of the motor.

2.4 Stepper motor driver circuit

Driver circuit of the stepper motor is the skeleton of the PCB machine. It receives

signals from the computer which determine in the direction of movement (angle)

and the distance. Also because at any time it receives step and direction signals

from the computer it translates the information to certain values of voltage and

current to be sent to the stepper motors.


07

The power Sent to the stepper motor windings is distributed to the windings in a

sequence which moves the stepper motor in the desired direction by the number

of steps equivalent to the distance to be made in the direction of this axis.

Three driver circuit are used, one for each axis direction of movement. The board

is designed using a set of integrated circuit of type L297 and L298 as show in

figure2.5.1 The advantage of using these integrated circuits (ICs) ease and

simplicity of design of the bored as it requires the least number of components,

another feature is that this could create a driver circuit with high-capacity capable

of handling up to 36 volts voltage and current up to 2 amperes per channel. Many

of stepper motors are bipolar or unipolar can be used at these rates of voltage and

current. The stepper motors data used here in the PCB machine as follow in the

next table.

Axis Type Modal step Volatge Curent

X Asyton --------- 1.8 degree 5 volt 1.5 amp

Y Vexta Ph 268 1.8 degree 5.4 volt 1.5 amp

Z vexta C679 1.8 degree 4.5 volt 1 amp

Table 2.2 List the motor used in the machine.

2.4.1 Brief explanation of the driver circuit

2.4.1.1 Brief list of the circuit components

Part Quantity Description

U1 1 L298 Dual full-bridge driver

U2 1 L297 stepper motor controller

D1-D8 8 FR 304 fast recovery diode

C1 1 3.3 NF capactitor

C2,C3 2 0.1 UF capacitor

C4 1 470 UF capacitor

C5,C6 2 1 NF capacitor

R1,R2 2 0.5 ohm power resistor

R3 1 1k ohm resistor


R5 1 2k2 ohm resistor


R7,R8 2 4.7 ohm resistor

JP1-JP6 3-3 pin , 2-4 pin Cut to size from header

material

Heat S ink 1 Heat sink must be installed on

the L298

Table 2.3: Show the drive circuit componant.


08

Figure 2.13: Stepper motor driver circuit drawn with proteus program.


11

2.4.1.2 Operation of drive circuit

This circuit operates by receiving signals from the parallel port on the pin 17 of

the integrated circuit L297 to control the direction of stepper motor. Pin 18 of

chip L297 is used to control the number of steps that will take the stepper

motor in this direction. Then the L297 send the signals to the L298 on the

sequence and the appropriate order, which must feed the stepper motor

windings to do the job required.

It will be noticed that the stepper motor capacity is provided only for the

integrated circuit for this purpose. But both L297 and L298 integrated circuits

need to +5 V to do their function.

The Eight diodes ( FR304) cut or clamp the voltage between the stepper motor

windings and the ground. Diodes used for this purpose should be of a property

fast recovery, but can be another number depending on the rate of voltage and

current required to drive the used stepper motor.

These diodes protect the L298 from the high induction voltages generated by

the stepper motor during winding disconnection.

pin 1 and 15 of the L298 connected to the ground through power resistors of half 0.5 .

Resistance connected to leg 1 is for drawing current from two windings of field , while the resistance connected to leg15 draws power from the other two

windings. These resistors give the the L297 chip the control means for

measuring current generated inside the stepper motor.

The L297 chip measuring voltage drop between the two sides of the resistors to control the chopper circuit with pulse width modulation system ( PWM

chopper), which is used in controlling the current flowing through the stepper

motor windings.

2.2K and 10K resistors connected to leg 15 (Vref) of the L297 chip used as voltage divider.

The output and applied voltage ( Vref ) on the leg 15 used to determine the set point voltage with the mesured voltage coming from the field windings.

When reach to a set point, contral sgnial is disconnected from the L298 chip (separate the windings) and allows the diodes FR304 to dicharge the field

windings.


10

Field windings in case of separation remains OFF until the end time of the internal oscillator of the L297 chip and then the field windings is connected

ON again.

22K resistance and capacitor 3.3 nF connected to leg 16 of L297 chip determines the time rate of the oscillator.

Capacitors C2, C3, C4 that filter power source for electronics and motors.

JP1 link is for the supply of power and Ground to the circuit and motors. JP2 link is a bridge to connect the circuit connected to leg 1 to leg16 of the L297

chip to one driver circuit , while other panels are plug the leg16 for L297 to the

ground.

In JP3 link, pin 1 recive step signals, while pin 2 recive direction signals, pin 3 used to connect all boards to be synchronized and pin 4 is the ground.

JP4 link dedicated to making thepin 19 of the L297 chip in case the logical high by pin 1 to provide the motor driving the maximum step, or in the logical

low state by pin 3 for half a step.

JP5 link is used to makmakelag 11 of the L297 chip in case of high, through pin 1 to use phase driving or in the case low through pin 3 to prevent the

inhibit drive.

2.4.2 The interface board

This board is the only gate (entrance) which allows the computer to send and

receive signals to the panel drivers and the limit switches. Do not have much a

link cable with parallel port and some links to connect the driver boardsand

limit switches fig 2.13 show Interface board componant.

2.4.2.1 Brief list of interface board component

Part Quantity Description

Conn 1 1 DB 25 connector

R1-17 17 4.7 ohm resistor

JP1-5 1-17 Pin , 5-2 Pin Header material

Table 2.4: Obtain brief list of interface board componant.


11

Figure 2.14: Interface circuit diagram using proteus.

2.4.2.2 Operation of interface circuit

4.7K resistors determine the current for circuit protection and parallel

port. The best way to protect the parallel port is to use optical isolation

circuit or the use of a dedicated card connected to the parallel port.

Pins Connections of Panel

Pin1-17 in theJP1 link are connected to the 1-17pins of the parallel port of

the computer.

Link JP2: pin 1 connected to pin 10 of the JP1 link and pin 2 connected to

the groud.

Link JP3: pin 1 connected to pin 11of the JP1 link and pin 2 connected to

the groud.

Link JP4: : pin 1 connected to pin 12of the JP1 link and pin 2 connected to

the groud.

Link JP5:pin 1 connected to pin 13of the JP1 link and pin 2 connected to

the groud.


12

Pins 10,11,12,13 of JP1 link have been made independent so to connect

the limit switches easily.

Link JP6: pin 1 connected to the positive voltage 5V and pin 2 with the

ground.

The next step is to manufacture the printed circuit boards of the stepper drivers

circuit and the inter phase circuit.

2.5 Limit switches

2.5.1 Definition

A limit switch is a switch operated by the motion of a machine part or presence of

an object. They are used for control of a machine, as safety interlocks, or to count

objects passing a point.Here they are used to indicte the end of the path for eachof

the three axis of the PCB machine.

Figure 2.15: Limit switch construction.

2.5.2 Limit Switch operation

In most cases, a limit switch begins operating when a moving machine or a

moving component of a machine makes contact with an actuator or operating

lever that activates the switch. The limit switch then regulates the electrical

circuit that controls the machine and its moving parts.

These switches can be used as pilot devices for magnetic starter control circuits,

allowing them to start, stop, slow down, or accelerate the functions of an electric

motor. Limit switches can be installed into machinery as control instruments for

standard operations or as emergency devices to prevent machinery malfunction.

Most switches are either maintained contact or momentary contact models.


13

2.5.3 Limt switch circuit

The limit switches are connected to external circuit show in fig 2.16 and this

circuit switches off the drives when the limit is reached. The separate reference

switches are connected inputs to mach3 one pin can share all the inputs for an

axis and mach3 is responsible for controlling both limits and detecting home. The

switches can be interfaced by a keyboard emulator.

Figure 2.16: Limit switch circuit.

2.6 The spindle relay circuit

Spindle contraled by simple circuit consist of relay , diode , and mosft . Relay

conecting with mosft which recive its sgnial from any output pin of the interface

board.

Figure 2.16: Spindle switch circuit.


14

2.7 Emergency stop

The emergency stop, often called an estop.An estop is a useful button for

quickly shutting down PCB machine. It's not the same as the PCB machines

power button, which may be located under the machine or otherwise not easily

reachable, In the event of an emergency such as our PCB machine hitting a

knot of table or a motor getting locked up, we want to be able to quickly shut

off our machine, imagine trying to find the power button on a power strip thats

under the table or out of reach, and well begin to understand the value of

putting an estop on our machine in an easy-to-reach location. The emergency

stop circuit is same as limit switch circuit show in fig2.16.

Figure 2.18: Emergency stop.

Ch.3 Machine Design EDT 2012

62

Chapter (3)

Machine Design

3.1 Introduction

Mechanical design of PCB machine is very important and must be taking

into consideration the entire dimension, size and weight of all parts. Well

designed machine mean high accuracy because the accuracy of the machine

depends mainly on the mechanical design of all parts. Also vibration of

movable parts should be considered while designing the machine.

Supporters and Screw should be fixed and supported to prevent machine

errors.

Fig 3.1 show the principal construct of 3dimention PCB machine, the

spindle has three axes to move on (X, Y and Z axis). Moving

simultaneously in the three dimensions is necessary when making Holes.

There are three kinds of holes on PCBs; Holes for device insertion, via

holes, and fringe holes for board fixing. Each hole has two parameters:

Position and size (diameter). Hole quality is also important. Hole position

consists of X-Y coordinates measured from monitor screen upper left

corner. These parameters are used to position the drilling bit, whereas size

parameter is used to choose bit size (usually 0.7mm, 0.8mm).

Figure 3.1: General model of the PCB machine.


62

Hole data file supplied by the electronic software is for controlling the

drilling machine. The drill (comprising motor, chuck, and bit) is moved

horizontally to X-Y coordinates of a hole, then moved down in Z direction

to make the hole, then withdrawn and translated to another place.

The electro-mechanical system is responsible for the 3D motion to position

the drill, and should be of real industry standard to guarantee the force,

torque, precision, and robustness. The idea was to choose stepper motors

and linear axes for the mechanical system.

3.2 Mechanical design

3.2.1 Choosing anatomy of motion and design

The design and the shape of the project is determined by choosing a suitable

type that do the job at the best way and to fit the required need specifically,

and here is some of the designs and different types of machines available.

1. Fixed table type

Here the table where the printed circuit is attached to be fixed to the base

and the three axis is moved in the three dimensions to do the job.

Figure3.2: Fixed table type.


62

a- Fixed table with power screw in the middle

Figure 3.3: Fixed table with power screw in the middle.

b. Fixed table with sliding tower

Figure 3.4: Fixed table with sliding tower.

2. Movable table type

Here the table is free to move in one or two dimensions and the spindle could

be movable only in the Z dimension or Z&Y dimensions.

Figure 3.5: Movable table type.


62

3.2.2 Our machine design

Figure 3.6: Sketch for X direction module.

Figure 3.7: Sketch for Y& Z-Direction module.

Figure 3.8: General view for X & Y & Z-axis module.


03

Table show the parts of the design with dimension (Depth of MDF is 24 mm).

Part name Parts number Description Dimension Part symbol

X axis 2 Connected to

each other with

rods

95 cm* 20 cm A

Y axis 3 (2 plates)

vertical

(1plate)

horizontal

45 cm*20 cm

76 cm*20 cm

B

Z axis 3 (1plate)

Vertical

(2plate)

horizontal

35 cm *20 cm

Upper plate:15 cm

*20 cm

Lower plate :7.5cm

*20 cm

C

Z axis 1 Spindle holder 20 cm *25 cm D

Base table 1 The base

where the PCB

is fixed to.

75 cm *60 cm E

Bearing 12

Rod

and

Bushing

2cm diameter

X:75 cm ,

Y:75 cm

Z:35 cm

4 cm*4 cm

F

Coupling 3 Couple the

stepper motor

to the power

screw

3 cm

Inner diameter 1 cm

Outer diameter 1.5 cm

G

Power screw 3 X axis

Y axis

Z axis

75 cm ,diameter 1 cm

75 cm ,diameter 1 cm

35 cm, diameter 1cm

H

connecting

Screws

20

12

Connecting

MDF

Connecting

the motors

10 cm, diameter 0.5

cm

15 cm ,diameter 0.4

cm

I

J

Table 3.1: Parts of mechanical design.


03

Figure3.9: Show parts mentioned in table (3.1).

Figure3.10: Drawing show the individual three axis sketches on AutoCAD.


06

3.3 Linear motion system and Bearings

A complete linear motion system is a combination of a drive system and

linear bearing system. The linear motion system is responsible for three

primary tasks.

1) Support Machine Components

2) Guide the machine in a precise linear motion with minimal friction

3) Support secondary loads (Torque, Lateral Loads, etc)

A bearing is any of various machine elements that constrain the relative

motion between two or more parts to only the desired type of motion.

3.3.1 Types of bearings

1. Rods and Bushings

Linear slides are key to the design of a functional machine. These slides

are a half successful experiment. Using steel rod from the hardware store

and some brass and steel bushings. The brass material slides easier, but

ultimately is though the smaller size and unfinished rod is too prone to

binding. Alignment is critical in long travel.

Figure 3.11: Various shapes of the sliding rods bearing.


00

2. Linear Guides

Rails and guide blocks, also often referred to as simply linear guides, are high

end linear motion systems. Linear guide blocks and rail systems are, as the

name suggests, composed of two primary components. The linear rail, which

guides the guide blocks and provides a smooth and durable surface for linear

motion, and the Guide Block which rides on the rail and supports the load that

is to be moved.

Figure 3.12: linear guide.

3. V-Groove Wheels and Track Rollers

There are five basic types of anti-friction bearings: tapered, needle, ball,

spherical and cylindrical. Each is named for the type of rolling element it

employs.

A single-row deep-groove ball bearing, it is the most popular rolling

bearing. The inner and outer raceway grooves have curvature radii between

51.5 and 53% of the ball diameter for most commercial bearings. To

assemble these bearings, the balls are inserted between the inner and outer

rings.

Figure 3.13: The internal component of ball bearings.


03

Figure 3.14: Single-Row Deep-Groove ball bearing.

3.3.2 Used bearing type in our PCB machine

Here in this project the sliding rods and bushing are the used type. Cause

of more cheap and with good lubrication is smooth and suitable for the job.

Figure 3.15: The bearings of our machine.


03

3.4 power screw

3.4.1 Introduction

Screw threads are used extensively in mechanical systems to convert a

rotational motion into a translational motion.

The screw thread is basically a wedge that has been wrapped around a

cylindrical rod. In these simple machines, the wedge is called the driver and

the object that is lifted is called the follower.

The helix angle of the wedge is called the pitch angle. The pitch of the

screw is defined to be the axial distance P between corresponding points on

adjacent threads.

The lead is the distance that the nut travels parallel to the screw axis when

the nut is given a 360 rotation. For a single-threaded screw, the lead is the

same as the pitch. A double threaded screw has a lead twice the pitch, and

a triple-threaded screw has a lead three times the pitch, and so on. We

consider only single-threaded screws. If a single-threaded screw has n

threads per unit length of the screw. The pitch is P = 1/n.

Figure3.16: Illustrating calculation of the power screw.

A schematic representation of the application of power screws to a power

driven press is shown in fig 3.16. In use, a torque T is applied to the ends of

the screws through a set of gears, thus driving the head of the press

downward against the load. A square-threaded power screw with single thread having a mean diameter

dm , a pitch p , a lead angle , and a helix angle is loaded by the axial compression force F. we wish to find an expression for them torque required

to raise this load.


02

3.4.2 Machine calculation Calculating the steps per mm

1- Thread per mm (TPM)

42 thread for 6 cm

7 thread for 1 cm

TPM=7:10 = 0.7

2- The pitch = 1: TPM = 1:0.7 = 1.43

3-The effective screw pitch: is the distance the axis moves for one

revaluation of the screw

1 revaluation = 1.667 mm

4- Screw revaluation per mm = 1: effective screw pitch = 1:1.667

= 0.6 rev-mm

Calculating motor step per revaluation from the motor name plate

It have (1.8 degree per step), so number of motor steps = 360:1.8= 200step

Mach 3 step per mm = mach3 step * motor rev per mm

= 0.6 (rev per mm) * 200 (step per rev) = 120 step-mm

For inch it will be = 120 * 25.4=30485 inch

- setting the maximum motor speed

At use frequency =25000 Hz

Maximum velocity = (frequency *60): step per mm

= (25000*60):120 = 12500 mm- min or by inch = 492.126 inch- min

Figure3.17: Power screw diagram.


02

3.5 Manufacturing material

PCB machines are manufactured from group of materials with a physical

characteristics and mechanical considerations. There are several factors to

consider when choosing the material of which we design the machine parts.

3.5.1 Suitable material for PCB machine

Wood (solid woods, plywood) and Medium-density fiberboard (MDF) the

machine has no problems with these, and MDF (though cheap & IKEA-

like) cuts especially well. One issue with wood can be warping, larger

sheets of plywood are rarely completely flat, so if the design involves

cleanouts (more on these later) add extra depth to compensate.

Figure3.18: PCB machine made of MDF.

PVC Plastics such as Sinatra / Komatex lay flat, machine great provide good strength and can be hand-tooled easily. Also that PVC

plastics are used in most of prototypes


02

Figure 3.19: PCB machines made of plastic and PVC.

Metals the machine can be used with aluminum. Thin sheets of metal also available .but in that case a good bearing system should

be considered.

Figure3.20: PCB machine made of aluminum.

Used material in our project is the MDF wood, cause of it is cheap, available,

and easy handled in the manufacturing process.


02

3.6 Spindle and component box fixing

3.6.1 The router spindle

The spindle is a simple actual motor doing the cutting, with the help of a

cutting tool of course. In other words its the actual router of the PCB

machine.

Like most everything else involving PCB machines, there are a variety of

spindle types out there. As usual there are many factors involved when

choosing a spindle for either pre-build machine, or homemade PCB

machine.

It should be well informed as to the capabilities of the spindle before

deciding to buy it.

There are many important considerations. Such as, RPM, load ratings,

power requirements, and size.

Figure3.21: The spindle motor.

Our Spindle data

220 v Rated voltage

50-60 HZ Rated frequency

115 W Rated power input

8000-33000 r-min No-load speed

Table 3.2: Spindle data.


33

3.6.2 Component box

Figure 3.22: View of the component box.

Table of box dimensions:

Part Name Parts Number Dimensions

Wood parts (front and back) 2 71 cm * 20 cm

Cooling Fans (sides) 2 20 cm *17 cm

Wood parts (shelf) 1 66.2 cm *17 cm

Metal Hinges 2 6 cm

Table3.3: Dimensions of component box.

Figure3.23: Sketch of the component box.


33

3.7 Fixing the copper board (PCB)

3.7.1 Description

It must be determined how to fix the PCB to the base table, tightly linked,

without the presence of any mistakes so as not to affect the manufacturing

process of the PCB, here the methods of fixing the PCB is shown.

3.7.2 Available methods to fix the PCB

1- Fixing with metal angle stripe. The board is fixed by Installation by sealing between two slices of

metal that form an acute angle.

Figure 3.24: PCB fixed with metal stripe angle.

2- Fixing with Connecting bolts and A wooden ledge The board is fixed between two pieces of wood using screw nails.

Figure3.25: PCB fixed with nails.


36

3-Fixing with plastic strips

The board is fixed using plastic stripes on the edges.

Figure3.26: PCB fixed with plastic stripes.

3- Fixing with four screw nails The board is fixed to the flat table using 4 screw nails (Rose nail).

Figure3.27: PCB fixed with four nails on flat surface.

In Our PCB machine we used the forth type, because of suitable for our

spindle, minimize errors, and provide distributed stress on the PCB.


30

3.8 Fixing stepper motor

The stepper motor is fixed to the machine using four of Screw nut, Tied

tightly to prevent movement or vibration during operation. Also to ensure

high efficiency and not to oppose the power screw during rotation.

The stepper motor is coupled with the power screw through a coupler that

has two inner diameters, one for the stepper motor shaft and the other for the

power screw.

Figure3.28: Stepper Motor before and after fixing.

Ch.4 Programming Software EDT 2012

44

Chapter (4)

Programming Software

4.1 Introductions

Now we have our steppers motors attached to our PCB machine, its time to test. Well start

by the required software that is needed to control the PCB machine. Next, well show how to

properly configure each software. Finally, well give some simple tests that can perform to

verify weve wired up everything properly and that our PCB machine is ready for bigger and

better things.

4.2 Eagle, PCB G-code and control software

There are three types of software that well be using with our PCB machine. The first is eagle

this is specialized software that allows to design printed circuit boards. The second lazycam

software takes the design we created with the eagle software and converts it into a language

called G-Code or we can use another method to convert direct by eagle file to G-code using

features of eagle program where it promoted installed PCB G-code inside it the main program

screen shown in figure 4-1.This G-Code is then used by mach3 of software that send the G-

code to the PCB machine through the parallel port. Mash 3 is the actual application that talks

to PCB machine; it takes the G-Code from PCB G-code software and uses it to send the

proper electrical signals (via the drive circuits see Chapter 2) to the three motors.


45

Figure 4.1: Main screen of PCB-G-code.

4.3 The Mach3 control software

The Control application were going to be referencing in this chapter is Mach3. Its from

ArtSoft USA and is available in a free version and a commercial version. Both versions are

identical, but the free version is going to limit you to 500 lines of G-Code; the version that can

purchase removes this limitation (although it does have an upper limit of 10,000,000 lines of

G-Code).

Figure 4.2: The main screen of Mach3.

The first time we view the main screen of Mach3, there are a lot of buttons, readouts, and

other elements crowding the screen, and none of it is likely to be familiar to anyone


46

interested. But fortunately, there are only a handful of things needed to configure in the

software to get machine up and running.

4.4 Downloading and Installing Mach3

Before us showing how we configure the software, though, we needed to present where we

download a copy and install it. So, we visited www.machsupport.com, and clicked the

Downloads menu, selected mach and lazycam, and followed the instructions on the page that

opens to download the installation file. After downloading the installation file, doubled-click

it and followed the instructions to install it. When we get to the screen for creating a profile

shown in Fig 4.3, we just clicked the next button to skip it. The installation will also allow

installing lazycam, a CAM application that can work hand in hand with mach3 once we have

an eagle file that needs converting to G-Code. its available to choose install it or not; we

recommend going ahead and installing it as it doesnt take much hard drive space and we may

find it useful for generating G-Code.

Figure 4.3: Installing Mach3.

4.5 Parallel port


47

4.5.1 Function of parallel port

When IBM designed the original PC they provided an interface for connecting printers using a

25 conductor cable. This is the foundation of the Parallel port we have on most PCs today. As it is a

Very simple way of transferring data it has been used for many things other than connecting printers.

We can transfer files between PC, connect peripherals like scanners and of course control machine

tools using it.

Figure 4.4: Parallel port pins.

The connector on the PC is a 25 way female connector. Its sockets seen from the back

Of the PC are shown in fig 4.4. The arrows give the direction of information flow relative

To the PC. Thus, for example, pin 15 is an input to the PCB.

4.5.2 Parallel port installing

At some point in the installation, mach3 will want to install a parallel port driver, as shown in

Fig 4.5. This is normal, so click the next button and follow the instructions to allow mach3 to

install this driver.

Figure 4.5: Parallel port installing.


48

4.6 Configuring Mach3

Were anxious to take our PCB machine for a spin, so well get straight to the key

configurations. By the way if mach3 didnt open yet, double-click the mach3 mill icon on

desktop. Itll show a screen similar to Fig 4.2 appears. The reset button will be flashing, and

itll show a large collection of readouts. There arent that many configurations will need to

perform, and well walk through each of them.

4.6.1 Motor Outputs

Click the Motor Outputs tab, as shown in Fig 4.6. Verify that the X Axis, Y Axis, and Z Axis

row all have a green check mark in the Enabled column.

Next we change the values under Step Pin# and Dir Pin# as follows:

For X Axis Step Pin#: 2 Dir Pin#: 3

For Y axis Step Pin#: 4 Dir Pin#: 5

For Z axis Step Pin#: 6 Dir Pin#: 7

Figure 4.6: Verify that the three axes are all enabled.

4.6.2 Limit switches


49

Click the input signal tap as shown in Figure 4.7 and Verify that the X home, ++X and X

also Y and Z to have a green check mark in the enabled column. Next define the Port/Pin to

which each is connected as shown.

Figure 4.7: Limit switches Configuring.

4.6.3 Spindle

The next tab on config Ports & Pins is spindle setup. This is used to define the way in which

Your spindle is to be controlled. You may allow mach3 to do nothing with it, to turn the

spindle on and off or to have total control of its speed by using a Pulse width modulated

(PWM) signal or a step and direction signal. The dialog is shown in Figure 4.8 and fig 4.9

obtain that spindle has 17 as output pin.


50

Figure 4.8: Spindle setup.

Figure 4.9: Spindle Configuring.

4.6.4 Emergency Stop

Click the Input Signals tab than Scroll down the list until find the eStop listing, as shown in

Figure 4-9. We defined estop at pin 13


51

Figure 4.10: Emergency Stop Configuring.

4.6.5 Motor tuning and setup

Click the config menu in Mach3 and select Motor Tuning. Well see a window like the one in

Fig 4.11 open.

Figure 4.11: Single screen is used to easily configure all three motor settings.

There are three buttons of importance on this window: X Axis, Y Axis, and Z Axis. We must

click a button (e.g., Z Axis) to set specific values for that motor. After setting any values, we

must always click the Save Axis Settings button in the lower-right corner.


52

Then well configure the following fields for the X, Y, and Z-axis motors as follows:

Steps per Velocity Acceleration

X Axis 2000 21.75 36

Y Axis 2000 21.75 36

Z Axis 2000 21.75 36

4.7 Testing the machine

Now its time to test our machine. We want to test that the motors can move the spindle along

the three axes left/right. Connect our computer to the inter face board using a male-to-male

25-pin cable. Well attach one end to the inter face board and the other end to our computers

parallel port. Now plug in the power to the interface board and the power supply. Open mach3

and click the MDI (Alt-2) tab, as shown in Figure 4.12.Were going to tell various motors to

move by actually typing in G-Code on this screen.

Figure 4.12: Test PCB machine using the MDI tab.


53

The first thing we need to do is click the Zero X, Zero Y, and zero Z buttons to reset the initial

values for our motors to zero. Now if the big Reset button is blinking Fig 4.13 show that, click it;

it should stop blinking. Just above the Reset button is the Input box. Click inside the text field

and type in G00 X1. This is a simple bit of G-Code. When it is executed, Mach3 will instruct the

x-axis motor to spin. Press the Enter key to execute the command. Run a similar command-G00

X-1 and press enter. The axis motor spin in the opposite direction.

Figure 4.13: Use the input field to manually enter G-Code for testing.

Ch.5 Experimental Results and Conclusion EDT 2012

35

Chapter (5)

Experimental Results and Conclusion

5.1 Why this project

This project combines three separated fields, every field handle a main part of the

PCB machine

The mechanical field appears in the mechanical design that hold all the stresses and choosing a suitable linear

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