Computer Numerical Controller Project Report

1
COMPUTER NUMERICAL CONTROLLER
A Major Project Report Submitted
To
CHHATTISGARH SWAMI VIVEKANAND TECHNICAL
UNIVERSITY
BHILAI (C.G.), INDIA
In partial fulfillment
For the award of the diploma
Of
Diploma in engineering
in
Mr.JAYANT KUMAR RAI
By
OMPRAKASH SAHU
Under the guidance of
Mr.JAYANT KUMAR RAI
I/C H.O.D.ET&T
ET&T
R.K.R.GOVT.POLYTECHNIC
JANJGIR CHAMPA (C.G.)
Session:-2017-2018

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DECLARATION BY THE CANDIDATE
I the undersigned solemnly declare that the report of the thesis work entitled computer numerical
controller is based my own work carried out during the course of my study under the supervision of Mr
jayant kumar rai
I assert that the statements made and conclusions drawn are an outcome of the project work. I
further declare that to the best of my knowledge and belief that the report does not contain any part of any
work which has been submitted for the award of any other diploma in this University of India or any other
country. All helps received and citations used for the preparation of thesis have been duly acknowledged.
.
OM PRAKASH SAHU
Dept of Electronics & Telecommunication
RKR GOVERNMENT POLYTECHNIC
JANJGIR CHAMPA, CHHATTISGARH
_________________
(Project Supervisor)
JAYANT KUMAR RAI
H.O.D. (ET&T)
Dept of Electronics & Telecommunication
JANJGIR CHAMPA,CHHATTISGARH

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CERTIFICATE BY THE SUPERVISOR
This is to certify that the report of the thesis entitled COMPUTER NUMERICAL
CONTROLLER is a record of bonafide research work carried out by Omprakash Sahu
bearing Roll No.: 2682815019 & Enrollment No.: AR4428 under my guidance and
supervision for the award of Diploma of Engineering, in Electronics &
Telecommunication inEngineering in the faculty of Mr. Jayant Kumar Rai of
Chhattisgarh Swami Vivekanand Technical University, Bhilai (C.G.) India.
To the best of my Knowledge the thesis
 Embodies the work of the candidate him/herself,
 Has duly been completed,
 Fulfill the requirements of the ordinance relating to the D.E. degree of the University and
 Is up to the desired standard both in respect of contents and language for being referred to the
examiners
________________
Mr. JAYANT KUMAR RAI
H.O.D.(ET&T)
JANJGIR CHAMPA, CHHATTISGARH

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CERTIFICATE BY THE EXAMINER
This is to certify that the project work entitled COMPUTER NUMERICAL
CONTOLLER submitted by omprakash sahu Roll No: 2682815019, and Enrollment
No: AR4428 has been examined by the undersigned as a part of the examination for the
award of Diploma in Engineering, in the faculty of Jayant Kumar Rai of Chhattisgarh
Swami Vivekananda Technical University, Bhilai (C. G.).
__________________ ___________________
Internal Examiner External Examiner
Date: Date:

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ACKNOWLEDGEMENT
I would like to acknowledge my gratitude to a number of people who have helped me in different
ways for the successful completion of my thesis. I take this opportunity to express a deep sense of
gratitude towards my guide, Mr. Jayant Kumar Rai HOD (ET&T), Engineering & technology, for
providing excellent guidance, encouragement and inspiration throughout the project work. Without
his invaluable guidance, this work would never have been a successful one.
I am thankful to Mr.Parth Ghosh, Mr. Himanshu Dahariya and Mr. Narendra
Dewangan Faculty of RKR Govt Polytechnic, JanjgirChampafor their kind help and cooperation.
I feel immensely moved in expressing my indebtedness to my parents whose sacrifice,
guidance and blessings helped me to complete my work.
Lastly, My most sincere thanks to everyone, even the ones I've forgotten when writing this.
OMPRAKASH SAHU
Roll No. 2682815019
Enrollment No: AR4428

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ABSTRACT
This thesis presents the design of Mini CNC Machine. This machine has 2axes, namely the Xand Y axis.
Mini CNC machine is a small CNC machine that can operate like a normal CNC machine with a limited
area of the machining. The objectives of this project are to develop the mini CNC Machine and to develop
the software to control the machine. This thesis describes the development of the machine and the criteria
needed to build the machine. The Mini CNC Machine is initially sketched by referring to the criteria that
was decided. The criteria are the travel path length, type of linear motion, type of linear drive, motor and
controller, and type of material that used. This machine’s travel on the X axis is 15cm and Y axis is 15cm.
The linear motion was used is a round linear rail and the linear drive used was a sliding element, lead nuts
and lead screws. The motor used is a stepper motor with specification 2.1V and 3.0A. The frame material
used is aluminium. This material is used because it is light in weight, easy to handle and machine and it is
rust proof. The design was sketched using SolidWork software. For the next step is developing the wiring
for motor and develop the program to control the stepper motor. The ULN 2803 is used to convert the
signal from parallel port to specific winding energizing sequences to step the motor. The Visual Basic
software is used to program the motor movement.

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Contents
Chapter 1
1. Introduction
1.1 Resistance
1.2 Capacitor
1.3 Light emitting diode
1.4 Pcb
1.5 Transistor
1.6 Arduino nano
1.7 L293D IC
1.8 Servomotor
1.9 Staper motor
Chapter 2
2.1 Curicut diagram
2.2 Blok diagram
Chapter 3
3.1 Problem Statement
Chapter 4
4.1 Guideline methodology
4.2 Software system
Chapter 5
5.1 Advantage
5.2 Dsadvantage
5.3 Application
Chapter 6
6.1 Conclusion
6.2 Bibliography

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INTRODUCTION :-
OF PROJECT Mini CNC machine is the machine that is similar to the usual CNC machine. Mini
CNC machine is the small CNC machine that can operate like usual CNC machine but the area
of the machining is limited. CNC machine is all about using the computer as a means to control
machines that carves useful objects from solid block to material. For example, a CNC machine
might begin with a solid block of aluminium, and then carved away just the right material to
leave with a door handle. There are many types of CNC machine. The common CNC machines
are two-axis and three-axis CNC machine. The two- axis machine can move on vertical and
horizontal only which are X and Y axis. Three-axis machine can do movement starting with
three primary axis which are X, Y and Z axis. The Z axis is being parallel with the spindle . The
CNC machine operation starts with the collecting the data from the programming that extract
from the computer-aided design (CAD) and computer-aided manufacturing (CAM). The
programs produce the computer file and then will extract the command to operate the machine.
The program will be transfer via post-processor and then be loaded into the CNC machine to
start the machining. This is the flow of the CNC machine operation:
The CNC machine is a system. To complete the system of CNC machine, there are 4 components
which are mechanical design, drives module, system software and Automatically Programme
Tool (APT) postprocessor. For the mechanical design system, this part is the part of hardware of
machine which is the part body. For the drive system, the command signal was received from
microprocessor. Microprocessor is consisting of motors, amplifier units and a power supply. For
the software system, it is generate the program to the CNC machine to start the movement of
tools and workpiece. For the APT postprocessor, it was developed to produce the G-code and M-
code that can be used by the CNC machine. Besides that, CNC machine also include of wiring in
order to connect the power to the machine. To complete the whole CNC machine, all the
elements must be in the good condition and must put at the right place.

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1.1 RESISTANCE
It is a passive component having two terminals that are used to manage the current flow in the
circuit. A current that flows via a resistor is directly proportional to the voltage that appeared into
the resistor.
Resistors are of two types –i) Fixed Resistor – having a fixed value of resistance
ii) Variable Resistor – whose value of resistance can be changed for example if we have a
resistor of 5K then the value of resistance will vary from 0 to 5 k.
Value of resistance can be calculated with the help of multimeter or with the color code that is
visible on the resistor.
Fig:1.1 resistance
1.2Capacitor
It is a passive component with two terminals and used to store charges. Capacitors are mad up of
two conductors which are separated by the dielectric medium flows in between. It works when
potential difference applied across the conductors polarize the dipole ions to store the charge in
the dielectric medium.
Fig. 1.2 Capacitor

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1.3Light emitting Diode
Light-emitting diodes are elements for light signalization in electronics. The basic principle behind the
working of LED is electroluminescence. The Light emitting diode should be forward biased to get the
light. In Light emitting diodes, electrons are injected from low work function cathode to the conduction
band of the n-type semiconducting material and holes are injected from high work function anode to
the valence band ot the p-type semiconducting material. When the electron in the conduction band
combines with the hole in the valence band, energy is released. In case of indirect band gap
semicondutors, phonon will be released to conserve of both energy and momentum. But in case of
direct band gap semiconductor, light will be emitted whose wavelength depends on the band gap of the
semiconductor.
Fig.1.3 Light emitting diode
1.4 PCB
A Printed circuit board or PCB is used to mechanically support and electrically connect electronic
components using conductive pathways, or traces, etched from copper sheets laminated on to a non
conductive substrate. Alternatine names are printed wiring board and etched wiring board. A PCB
populated with electronic components is a printed circuit assembly, also known as a printed circuit board
assembly.
PCB’s are rugged, inex pensive and can be highly reliable. They require much more layout effort and
higher initial cost than either wire wrapped or point to point constructed circuits, but are much cheaper
and faster for high volume production. Much of the electronic industry’s PCB design, assembly and
quality control needs are set by standards that are published by the IPC organization.
Fig.1.4PCB

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1.5 Transistor
Transistors are three terminal active devices made from different semiconductor materials that
can act as either an insulator or a conductor by the application of a small signal voltage. The
transistor's ability to change between these two states enables it to have two basic functions:
switching or amplification. Then bipolar transistors have the ability to operate within three
different regions:
 Active Region - the transistor operates as an amplifier and IC = β IB
 Saturation - the transistor is fully-ON operating as a switch and IC = Isaturation
 Cut-off - the transistor is "fully-OFF" operating as a switch and IC = 0
Fig.1.5 transistor

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1.6 Arduino Nano
Overview
The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328
(Arduino Nano 3.0) or ATmega168 (Arduino Nano 2.x). It has more or less the same
functionality of the Arduino Duemilanove, but in a different package. It lacks only a DC power
jack, and works with a Mini-B USB cable instead of a standard one. The Nano was is being
designed and produced by Gravitech.
Fig:1.6( a)

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Schematic and Design
Arduino Nano 3.0 (ATmega328): schematic, Eagle files.
Arduino Nano 2.3 (ATmega168): manual (pdf), Eagle files.
Note: since the free version of Eagle does not handle more than 2 layers, and this version of the
Nano is 4 layers, it is published here unrouted, so users can open and use it in the free version of
Eagle.
Power:
The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external
power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is
automatically selected to the highest voltage source. The FTDI FT232RL chip on the Nano is
only powered if the board is being powered over USB. As a result, when running on external
(non-USB) power, the 3.3V output (which is supplied by the FTDI chip) is not available and the
RX and TX LEDs will flicker if digital pins 0 or 1 are high.
Memory
The ATmega168 has 16 KB of flash memory for storing code (of which 2 KB is used for the
bootloader); the ATmega328 has 32 KB, (also with 2 KB used for the bootloader). The
ATmega168 has 1 KB of SRAM and
512 bytes of EEPROM (which can be read and written with the EEPROM library); the
ATmega328 has 2 KB of SRAM and 1 KB of EEPROM.
Input and Output
Each of the 14 digital pins on the Nano can be used as an input or output, using pinMode(),
digitalWrite(), and digitalRead() functions. They operate at 5 volts. Each pin can provide or
receive a maximum of 40 mA and has an internal pull-up resistor (disconnected by default) of
20-50 kOhms. In addition, some pins have specialized functions:
Serial: 0 (RX) and 1 (TX).
Used to receive (RX) and transmit (TX) TTL serial data. These pins ar connected to the
corresponding pins of the FTDI USB-to-TTL Serial chip.
External Interrupts: 2 and 3
These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a
change in value. See the attachInterrupt() function for details.
PWM: 3, 5, 6, 9, 10, and 11.
Provide 8-bit PWM output with the analogWrite() function.
SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK).
These pins support SPI communication, which, although provided by the underlying hardware, is
not currently included in the Arduino language.
LED: 13.
There is a built-in LED connected to digital pin 13. When the pin is HIGH value, the LED is on,
when the pin is LOW, it's off.

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The Nano has 8 analog inputs, each of which provide 10 bits of resolution (i.e. 1024 different
values). By default they measure from ground to 5 volts, though is it possible to change the
upper end of their range using the analogReference() function. Additionally, some pins have
specialized functionality:
I2C: 4 (SDA) and 5 (SCL).
Support I2C (TWI) communication using the Wire library (documentation on the Wiring
website). There are a couple of other pins on the board:
AREF.
Reference voltage for the analog inputs. Used with analog Reference().
Reset.
Bring this line LOW to reset the microcontroller. Typically used to add a reset button to shields
which block the one on the board.
See also the mapping between Arduino pins and ATmega168 ports.
Communications
The Arduino Nano has a number of facilities for communicating with a computer, another
Arduino, or other microcontrollers. The ATmega168 and ATmega328 provide UART TTL (5V)
serial communication, which is available on digital pins 0 (RX) and 1 (TX). An FTDI FT232RL
on the board channels this serial communication over USB and the FTDI drivers (included with
the Arduino software) provide a virtual com
port to software on the computer. The Arduino software includes a serial monitor which allows
simple textual data to be sent to and from the Arduino board. The RX and TX LEDs on the board
will flash when
data is being transmitted via the FTDI chip and USB connection to the computer (but not for
serial communication on pins 0 and 1). A SoftwareSerial library allows for serial communication
on any of the Nano's digital pins. The ATmega168 and ATmega328 also support I2C (TWI) and
SPI communication. The Arduino software includes a Wire library to simplify use of the I2C
bus; see the documentation for details. To use the SPI communication, please see the
ATmega168 or ATmega328 datasheet.

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1.7 L293D IC
Introduction
L293D is a typical Motor driver or Motor Driver IC which allows DC motor to drive on either
direction. L293D is a 16-pin IC which can control a set of two DC motors simultaneously in any
direction. It means that you can control two DC motor with a single L293D IC.In a single L293D
chip there are two h-Bridge circuit inside the IC which can rotate two dc motor independently.H-
bridge is a circuit which allows the voltage to be flown in either direction.H-bridge IC are ideal
for driving a DC motor.Due its size it is very much used in robotic application for controlling DC
motors.Click here for L293D datasheet.
Working of L293D
There are 4 input pins for l293d, pin 2,7 on the left and pin 15 ,10 on the right as shown on the
pin diagram. Left input pins will regulate the rotation of motor connected across left side and
right input for motor on the right hand side. The motors are rotated on the basis of the inputs
provided across the input pins as LOGIC 0 or LOGIC 1. For rotating the motor in clockwise
direction the input pins has to be provided with Logic 1 and Logic 0.Enable pins 1 and 9
(corresponding to the two motors) must be high for motors to start operating. When an enable
input is high, the associated driver gets enabled. As a result, the outputs become active and work
in phase with their inputs. Similarly, when the enable input is low, that driver is disabled, and
their outputs are off and in the high-impedance state.
Fig.1.7 L293D IC (a)

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Pin
No.
Pin Characteristics
1
Enable 1-2, when this is HIGH the left part of the IC will work and when it is low the left
part won’t work. So, this is the Master Control pin for the left part of IC
2 INPUT 1, when this pin is HIGH the current will flow though output 1
3 OUTPUT 1, this pin should be connected to one of the terminal of motor
4,5 GND, ground pins
8
VC, this is the voltage which will be supplied to the motor. So, if you are driving 12 V DC
motors then make sure that this pin is supplied with 12 V
16 VSS, this is the power source to the IC. So, this pin should be supplied with 5 V
13,12 GND, ground pins
9
Enable 3-4, when this is HIGH the right part of the IC will work and when it is low the
right part won’t work. So, this is the Master Control pin for the right part of IC
Fig.1.7(b)

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How Motor Driver Operates?
The L293D IC receives signals from the microprocessor and transmits the relative signal to the
motors. It has two voltage pins, one of which is used to draw current for the working of the
L293D and the other is used to apply voltage to the motors. The L293D switches it output signal
according to the input received from the microprocessor.
For Example: If the microprocessor sends a 1(digital high) to the Input Pin of L293D, then the
L293D transmits a 1(digital high) to the motor from its Output Pin. An important thing to note is
that the L293D simply transmits the signal it receives. It does not change the signal in any case.
Why We Need Motor Driver IC?
Motor Driver ICs are primarily used in autonomous robotics only. Also most microprocessors
operate at low voltages and require a small amount of current to operate while the motors
require a relatively higher voltages and current . Thus current cannot be supplied to the motors
from the microprocessor. This is the primary need for the motor driver IC.
1.8 SERVOMOTOR
Servo implies an error sensing feedback control which is utilized to correct the performance of a
system. It also requires a generally sophisticated controller, often a dedicated module designed
particularly for use with servomotors. Servo motors are DC motors that allows for precise
control of angular position. They are actually DC motors whose speed is slowly lowered by the
gears. The servo motors usually have a revolution cutoff from 90° to 180°. A few servo motors
also have revolution cutoff of 360° or more. But servo motors do not rotate constantly. Their
rotation is limited in between the fixed angles The servo motor is actually an assembly of four
things: a normal DC motor, a gear reduction unit, a position-sensing device and a control
circuit. The DC motor is connected with a gear mechanism which provides feedback to a
position sensor which is mostly a potentiometer. From the gear box, the output of the motor is
delivered via servo spline to the servo arm. For standard servo motors, the gear is normally made
up of plastic whereas for high power servos, the gear is made up of metal. A servo motor consists
of three wires- a black wire connected to ground, a white/yellow wire connected to control unit
and a red wire connected to power supply.
The function of the servo motor 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.

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It uses the position sensing device to figure out the rotational position of the shaft, so it knows
which way the motor must turn to move the shaft to the instructed position. The shaft commonly
does not rotate freely around similar to a DC motor, however rather can just turn 200 degrees
From the position of the rotor, a rotating magnetic field is created to efficiently generate toque.
Current flows in the winding to create a rotating magnetic field. The shaft transmits the motor
output power. The load is driven through the transfer mechanism. A high-function rare earth or
other permanent magnet is positioned externally to the shaft. The optical encoder always watches
the number of rotations and the position of the shaft.
Fig 1.8 (a)servomotor
Working of a Servo Motor
The Servo Motor basically consists of a DC Motor, a Gear system, a position sensor and a
control circuit. The DC motors get powered from a battery and run at high speed and low
torque. The Gear and shaft assembly connected to the DC motors lower this speed into sufficient
speed and higher torque. The position sensor senses the position of the shaft from its definite
position and feeds the information to the control circuit. The control circuit accordingly decodes
the signals from the position sensor and compares the actual position of the motors with the

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desired position and accordingly controls the direction of rotation of the DC motor to get the
required position. The Servo Motor generally requires DC supply of 4.8V to 6 V.
Controlling a Servo Motor
A servo motor is controlled by controlling its position using Pulse Width Modulation Technique.
The width of the pulse applied to the motor is varied and send for a fixed amount of time.
The pulse width determines the angular position of the servo motor. For example a pulse width
of 1 ms causes a angular position of 0 degrees, whereas a pulse width of 2 ms causes a angular
width of 180 degrees.
Fig.1.8(b)
Advantages:
 If a heavy load is placed on the motor, the driver will increase the current to the motor coil as
it attempts to rotate the motor. Basically, there is no out-of-step condition.
 High-speed operation is possible.
Disadvantages:
 Since the servomotor tries to rotate according to the command pulses, but lags behind, it is
not suitable for precision control of rotation.
 Higher cost.
 When stopped, the motor’s rotor continues to move back and forth one pulse, so that it is not
suitable if you need to prevent vibration

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1.9 STEPERMOTOR:-
A stepper motor or step motor or stepping motor is a brushless DC electric motor that divides
a full rotation into a number of equal steps. The motor's position can then be commanded to
move and hold at one of these steps without any position sensor for feedback (an open-loop
controller), as long as the motor is carefully sized to the application in respect to torque and
speed.
Switched reluctance motors are very large stepping motors with a reduced pole count, and
generally are closed-loop commutated.
A step motor can be viewed as a synchronous AC motor with the number of poles (on both rotor
and stator) increased, taking care that they have no common denominator. Additionally, soft
magnetic material with many teeth on the rotor and stator cheaply multiplies the number of poles
(reluctance motor). Modern steppers are of hybrid design, having both permanent magnets
and soft iron cores.
To achieve full rated torque, the coils in a stepper motor must reach their full rated current during
each step. Winding inductance and counter-EMF generated by a moving rotor tend to resist
changes in drive current, so that as the motor speeds up, less and less time is spent at full current
— thus reducing motor torque. As speeds further increase, the current will not reach the rated
value, and eventually the motor will cease to produce torque.
Pull-in torque
This is the measure of the torque produced by a stepper motor when it is operated without an
acceleration state. At low speeds the stepper motor can synchronize itself with an applied step
frequency, and this pull-in torque must overcome friction and inertia. It is important to make sure
that the load on the motor is frictional rather than inertial as the friction reduces any unwanted
oscillations.
The pull-in curve defines an area called the start/stop region. Into this region, the motor can be
started/stopped instantaneously with a load applied and without loss of synchronism.
Pull-out torque
The stepper motor pull-out torque is measured by accelerating the motor to the desired speed and
then increasing the torque loading until the motor stalls or misses steps. This measurement is
taken across a wide range of speeds and the results are used to generate the stepper
motor's dynamic performance curve. As noted below this curve is affected by drive voltage,
drive current and current switching techniques. A designer may include a safety factor between
the rated torque and the estimated full load torque required for the application.
Detent torque
Synchronous electric motors using permanent magnets have a resonant position holding torque
(called detent torque or cogging, and sometimes included in the specifications) when not driven
electrically. Soft iron reluctance cores do not exhibit this behavior.
Ringing and resonance
When the motor moves a single step it overshoots the final resting point and oscillates round this
point as it comes to rest. This undesirable ringing is experienced as motor vibration and is more

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pronounced in unloaded motors. An unloaded or under loaded motor may, and often will, stall if
the vibration experienced is enough to cause loss of synchronisation.
Stepper motors have a natural frequency of operation. When the excitation frequency matches
this resonance the ringing is more pronounced, steps may be missed, and stalling is more likely.
Motor resonance frequency can be calculated from the formula:
Fig1.9 (a)- Stepper motor
Stepper motor ratings and specifications
Stepper motors' nameplates typically give only the winding current and occasionally the voltage
and winding resistance. The rated voltage will produce the rated winding current at DC: but this
is mostly a meaningless rating, as all modern drivers are current limiting and the drive voltages
greatly exceed the motor rated voltage.
Data sheets from the manufacturer often indicate Inductance. Back-EMF is equally relevant, but
seldom listed (it is straightforward to measure with an oscilloscope). These figures can be helpful
for more in-depth electronics design, when deviating from standard supply voltages, adapting
third party driver electronics, or gaining insight when choosing between motor models with
otherwise similar size, voltage, and torque specifications.
A stepper's low speed torque will vary directly with current. How quickly the torque falls off at
faster speeds depends on the winding inductance and the drive circuitry it is attached to,
especially the driving voltage.

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Steppers should be sized according to published torque curve, which is specified by the
manufacturer at particular drive voltages or using their own drive circuitry. Dips in the torque
curve suggest possible resonances, whose impact on the application should be understood by
designers.
Step motors adapted to harsh environments are often referred to as IP65 rated.[6]
The US National Electrical Manufacturers Association (NEMA) standardises various aspects of
stepper motors. They are typically referred with NEMA DD, where DD is the diameter of the
faceplate in inches × 10 (e.g., NEMA 17 has diameter of 1.7 inches). There are further specifiers
to describe stepper motors, and such details may be found in the ICS 16-2001 standard (section
4.3.1.1). There are also useful summaries and further information on the Reprap site.
Fig1.9 (b)- Stepper motor
Application
Computer controlled stepper motors are a type of motion-control positioning system. They are
typically digitally controlled as part of an open loop system for use in holding or positioning
applications.
In the field of lasers and optics they are frequently used in precision positioning equipment such
as linear actuators, linear stages, rotation stages, goniometers, and mirror mounts. Other uses are
in packaging machinery, and positioning of valve pilot stages for fluid control systems.
Commercially, stepper motors are used in floppy disk drives, flatbed scanners, computer
printers, plotters, slot machines, image scanners, compact disc drives, intelligent lighting, camera
lenses, CNC machines and, more recently, in 3D printers.

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Stepper motor system
A stepper motor system consists of three basic elements, often combined with some type of user
interface (host computer, PLC or dumb terminal):
Indexers
The indexer (or controller) is a microprocessor capable of generating step pulses and direction
signals for the driver. In addition, the indexer is typically required to perform many other
sophisticated command func
The driver (or amplifier) converts the indexer command signals into the power necessary to
energize the motor windings. There are numerous types of drivers, with different voltage and
current ratings and construction technology. Not all drivers are suitable to run all motors, so
when designing a motion control system the driver selection process is critical.
Stepper motors
The stepper motor is an electromagnetic device that converts digital pulses into mechanical shaft
rotation. Advantages of step motors are low cost, high reliability, high torque at low speeds and a
simple, rugged construction that operates in almost any environment. The main disadvantages in
using a stepper motor is the resonance effect often exhibited at low speeds and decreasing torque
with increasing speed.
Advantage
 Low cost for control achieved
 High torque at startup and low speeds
 Ruggedness
 Simplicity of construction
 Can operate in an open loop control system
 Low maintenance
 Less likely to stall or slip
 Will work in any environment

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Block Diagram –
Runing process of cnc machine block diagram-
IMAGE INKSCAPE
PHOTOSHOP
G-CODE
CONVERT
SAVE
FILE
PROCESSING 3OPNE G-CODE
FILE
RUN CNC
MACHINE

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PROBLEM STATEMENT :-
Nowadays, the world are becoming highly technology with a lot of things become smaller and thinner.
Even now the things especially in engineering and technology have the things in nano and micro size.
Same goes to CNC Machine; this machine is now has variety of size in the market. All type of machine
have own purpose, eventhough the size is big or small. The usual CNC machine can machine the big
workpiece depends on the machine specification. The mini CNC machine only can machine the small
workpiece depend on the machine specification. This project is about to overcome the problem of
machining the small part. Even the usual CNC machine can machine the small workpiece, it will increase
the time on setup the workpiece to the machine to get the accurate result. The mini CNC machine will
give the small area of setup the workpiece and it will be easier to get the accurate place or result for the
workpiece.

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GUIDELINE METHODOLOGY :-
The start of the flow work is to understand the fundamental of the Mini CNC machine. After doing some
research and study about the Mini CNC machine, the next step that is needed to do is design the machine
according to the understanding of the mini CNC machine concept. The designing of the machine
including with the wiring connection and the software that is use to generate the program. Develop the
machine base of the design that has been drawn.
The Fundamental Of The Mini CNC Machine
In these four modules, he elaborates the part one by one which is module by module. First module is
about the mechanical design. Mechanical design of the machine involves conceptual of overall
configuration of the machine, drafting and design analysis made to satisfy geometrical and force
constrain. In this module, the machine specification is identified and the power for machining aluminium
is calculated. The second module is the drive module. This module show that the controller of the
machine which is microprocessor that is receive the command signals. Drive module is consisting of
motors, amplification units, and a power supply. The control signals are the first generated by the
microprocessor to determine the direction of rotation of the motor. 8 The third module is system software.
The system software can be defined as an instruction set required executing the functions of the system
through a set physical component. The software system is designed to generate automatic stops for the
tool and workpiece movements. This is done because the unit operates in the open loop mode. Lastly, the
fourth module is the Automatically Programmed Tool (APT) postprocessor. APT is a language that is
used to control a variety of operations in machining and that is generating from the CAD/CAM software
system. The APT postprocessor was developed to produce G-codes and M-codes that can be used by
CNC machine constructed from the APT files produced by commercial CAD software. From the book
CNC Machines by B. S. Pabla, M. Adithan, they state that there are some features in CNC machine tools
(B. S. Pabla, 1994). The features are:-
 The part programme can be input to the controller unit through key-board or the paper tape can be read
by the tape reader in control unit
 The part programme once entered in to the computer memory can be used again and again
 The part programme can be edited and optimised at the machine tool itself
 The input information can be reduced to a great extent with the use of special subprogrammes
developed for repetitive machining sequence
 The CNC machines have the facility for proving the part programme without actually running it on the
machine tool
 CNC control unit allows compensation for any changers in the dimension of cutting tool
 With the CNC control system,
It is possible to obtain information on machine utilisation which is useful to management The combined
characteristics of the machine tool and the control determine the precision of positioning. Three critical
measures of precision are resolution, accuracy and repeatability. Control resolution (BLU) is the distance
separating two adjacent points in the axis movement (the smallest change in the position) . The
electromechanical components of 9 the positioning system that affect the resolution are the leadscrew
pitch, the gear ratio, and the step angle in the stepping motor (open loop) or the angle between the slots in
the encoder (closed-loop). Accuracy of a CNC system depends on the resolution, the computer control
algorithms, and the machine inaccuracies. The inaccuracy due to the resolution is considered to be (1/2)
BLU on the average. The control algorithm inaccuracy is due to the rounding off the errors in the

36
computer which is insignificant. Repeatability is a statistical term associated with accuracy. It refers to the
capability of a positioning system to return to a programmed point, and is measured in terms of the errors
associated with the programmed point. The deviation from the control point (error) usually follows a
normal distribution in which case the repeatability may be given as +/- 3a where a is the standard
deviation. The repeatability is always better than the accuracy. The mechanical inaccuracy can be
considered as the repeatability.

37
Software system :-
The software involves the building of an interpreter for the part program. The part program executed by
the microprocessor consists of a series of instructions. Each instruction comprising a string of binary
digits is decoded by the microprocessor and is then executed. The microprocessor requires these
instructions to be written in Op-codes. An Opcode is an instruction that is composed of hexadecimal
characters. The interpreter translates the G-codes into equivalent Op-codes. The software for the system is
designed to generate automatic stops for the tool and workpiece movements. This is done because the unit
operates in the open loop mode. The backlash in the screw rod is estimated and the software is corrected
for this error. The system software is developed by adopting the modular programming format. A module
may be termed as a subroutine that forms a part of the main program. Every module comprises a set of
general purpose instructions that can be accessed when required during the course of execution of the
program. All the G-codes require stepping motors to be switched on and off. One module is set apart for
switching on the stepper motors. This module is accessed by all the 'G' functions which mean that this
module does not belong to any particular G-code. Initially, the system software is loaded in random
access memory (RAM) of the microprocessor for testing purposes. After the credibility of the program
has been established, the addresses of the Op-codes are located in the ROM (read only memory) area
designated by the makers of the microprocessor kit. The programs are then loaded into an erasable
programmable read only memory (EPROM) to form a permanent part of the system, until a hardware
erasure is affected. This is in contrast to the operation of a RAM, which loses its contents once the system
is switched off. The EPROM instructions are not accessible to the user. By removing the EPROM from
the system software for milling, and inserting another EPROM into the microprocessor, which perhaps
has lathe system software, the controller that is used to control a CNC 12 milling machine can then be
used to control a CNC lathe. Once the software has been developed and tested, the manufacture of the
system proves easy because the general purpose microprocessor loaded with this software in ROM
becomes specific to the machine tool. The machine operates in two modes - the manual mode and the
automatic mode. The manual mode allows the motion in the machine to be controlled by manually
pressing the appropriate keys. The automatic mode allows the execution of the instructions in the part
program. First, the machining parameters are determined. Second, the optimal sequence of operations is
evaluated. Third, the tool path is calculated. Fourth, a program is written. Each line of the program,
referred to as a block, contains the required data for transfer from one point to the next. A typical line for
a program is given below. N100 G91 X -5.0 Y7 .0 F100 S200 T01 M03 (EOB) The significance of each
term is explained below. Sequence Number, N. Consisting of typically three digits, its purpose is to
identify the specific machining operation through the block number particularly when testing a part
program. Preparatory Function, G. It prepares the MCU circuits to perform a specific operation. The G-
codes. G91 implies incremental mode of operation. Dimension Words consist of Distance dimension
words, X, Y, Z, Circular dimension words, I, J, K for distances to the arc center and angular dimensions,
A, B. C

39
ADVANTAGES:-
1. CNC machines can be used continuously 24 hours a day, 365 days a year and only need to be
switched off for occasional maintenance.
2. CNC machines are programmed with a design which can then be manufactured hundreds or
even thousands of times. Each manufactured product will be exactly the same.
3. Less skilled/trained people can operate CNCs unlike manual lathes / milling machines etc..
which need skilled engineers.
4. CNC machines can be updated by improving the software used to drive the machines
5. Training in the use of CNCs is available through the use of ‘virtual software’. This is software
that allows the operator to practice using the CNC machine on the screen of a computer. The
software is similar to a computer game.
6. CNC machines can be programmed by advanced design software such as Pro/DESKTOP®
,
enabling the manufacture of products that cannot be made by manual machines, even those used
by skilled designers / engineers.
7. Modern design software allows the designer to simulate the manufacture of his/her idea. There
is no need to make a prototype or a model. This saves time and money.
8. One person can supervise many CNC machines as once they are programmed they can usually
be left to work by themselves. Sometimes only the cutting tools need replacing occasionally.
9. A skilled engineer can make the same component many times. However, if each component is
carefully studied, each one will vary slightly. A CNC machine will manufacture each component
as an exact match
DISADVANTAGE:-
1. CNC machines are more expensive than manually operated machines, although costs are
slowly coming down.
2. The CNC machine operator only needs basic training and skills, enough to supervise several
machines. In years gone by, engineers needed years of training to operate centre lathes, milling
machines and other manually operated machines. This means many of the old skills are been
lost.
3. Less workers are required to operate CNC machines compared to manually operated
machines. Investment in CNC machines can lead to unemployment.
4. Many countries no longer teach pupils / students how to use manually operated lathes / milling
machines etc... Pupils / students no longer develop the detailed skills required by engineers of the
past. These include mathematical and engineering skills.

40
APPLICATIONS:-
The applications of CNC include both for machine tool as well as non-machine tool areas. In the
machine tool category, CNC is widely used for lathe, drill press, milling machine, grinding unit,
laser, sheet-metal press working machine, tube bending machine etc. Highly automated machine
tools such as turning center and machining center which change the cutting tools automatically
under CNC control have been developed. 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.

42
Conclusion:-
With the increasing demand for small scale high precision parts in various industries, the market for small
scale machine tools has grown susbtantially. Using small machine tools to fabricate small scale parts can
provide both flexibility and efficiency in manufacturing approaches and reduce capital cost, which is
beneficial for small business owners and hobbyists. In this thesis, a small scale three axis CNC milling
machine is designed and analyzed under very limited budget of 2,000 USD. During the structure design
stage, various common structure frames are explored and analyzed. The most suitable structure frame, the
open frame vertical type structure, is chosen. Critical components such as linear guides, motors, and
enocders are selected among few different options. The best value components are selected to
accommodate stiffness requirements and budget constraints. The issues of assembling mechanical
components and emerging electrical parts into mechanical structure are all well considered. A prototype
machine is assembled in the lab and Delta Tau's UMAC PLC is used as motion controller of the machine.
The detailed steps of how to setup and configuring the PLC is described in chapter 5. An attempt to make
a servo controller particularly for this machine is also conducted. The completed machine is tested using
three different techniques, i.e. surface testing, perpendicularity testing and circular testing. The possible
100 error sources are determined. The prototype machine has been used to create several parts already.
Due to inaccuracy of the machine body parts and rough assembling, the machine fails to achieve the
desired precision and repeatability level. However, it is still sufficient to create small features such as
letters and graphs with sizes less than 1cm. A new design is created after evaluating this prototype with
features of calibration and ease of assembling. This will certainly help to achieve the desired
characteristics with the same amount of budget.

43
:
 W.W.W.google.com
 Raipur mahalaxmi electronics
 http://www.motioncontrolonline.org/i4a/pages/index.cfm?pageid=3601

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