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International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 6, June 2017, pp. 463–470, Article ID: IJMET_08_06_048

Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=6

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

DEVELOPMENT OF AN OPEN TYPE CNC

SYSTEM FOR A 3-AXIS MICRO CNC MACHINE

Lakshmipathi Yerra, K. Chinnamaddaiah and Subramanyam B

Department of Mechanical Engineering,

MLR Institute of Technology, Hyderabad, Telangana, India

P. Ravikanth Raju

Department of Mechanical Engineering, Anurag Group of Institutions,

Ghatkesar (M), R.R. Dist., Telangana, India

ABSTRACT

The technologies on microminiaturization have a worldwide practical application

prospect. Current researches require fabrication techniques which can effectively and

economically produce micro-scale components with complex 3D features over a wide

range of material types. Comparing to macro mechanical machining processes, micro

mechanical machining such as micro milling can create complicated micro structures

on various materials using miniature tools with high material removal rates.

In order to improve the machining performance to provide high accuracy, it is

necessary to develop a proper CNC system for this machine tool. For the requirements

of actual micro machining, some special features designed by the users should be

added into the control system which usually has been integrated in commercial

software provided by suppliers as a “grbl”. So it is difficult to develop the efficient

and economic CNC system. Open CNC system is also called as Open-architecture

CNC system, it could be complimentary technology to achieve high reliability control

and multiple machining tasks. In this system most integrated functions could run as

real-time parallel processes.

The main objective of this project is to develop an open type CNC system for a 3

axis micro CNC machine and evaluate the performance of the whole system for the

following machining experiments.

Key words: CNC, Micro system, 3-Axis.

Cite this Article: Lakshmipathi Yerra, K. Chinnamaddaiah, Subramanyam B and

P. Ravikanth Raju. Development of an Open Type CNC System for a 3-Axis Micro

CNC Machine. International Journal of Mechanical Engineering and Technology,

8(6), 2017, pp. 463–470.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=6

Development of an Open Type CNC System for a 3-Axis Micro CNC Machine


1. INTRODUCTION

Increase in the rapid growth of Technology significantly increased the usage and utilization of

CNC systems in industries but at considerable expensive. The idea on fabrication of low cost

CNC came forward to reduce the cost and complexity in CNC systems. This paper discusses

the development of a low cost CNC which is capable of 3-axis simultaneous interpolated

operation. The lower cost is achieved by incorporating the features of a standard PC interface

with micro-controller based CNC system in an Arduino based embedded system. The system

also features an offline G-Code parser and then interpreted on the micro-controller from a

USB. Improved procedures are employed in the system to reduce the computational

Overheads in controlling a 3-axis CNC machine, while avoiding any loss in overall system

performance.

2. WORKING PRINCIPLE

Computer numerical control machine tools are such type of machine tools that have

revolutionized machining processes. It is nothing but using a computer as a mean to control a

machine that produces useful objects from solid blocks of material. CNC machine works

under a close loop system that means when an operation is performed by executing a

program, a feedback is coming back to the CNC system. This is not a descriptive answer of

what is CNC machine. The working principle of Micro CNC system block diagram as shown

in figure.1.

3. COMPONENTS OF CNC

The usual CNC milling machine requires different tools in order to serve different functions.

This feature enables the CNC milling machine to execute several functions in one operation.

The machine operator is not required to change the tool for the machine to perform another

function. Automatic tool changer, CAD/CAM system software, display unit, is shown in

figure.2, 3, 4. G-codes and M-codes will be use in the CNC system.

3.1. 3-Axis Micro CNC Machine

Machine structure is the “backbone” of the machine tool. It integrates all machine

components into a complete system. The machine structure is crucial to the performance of

the machine tools since it is directly affecting the static and dynamic stiffness, as well as the

damping response of the machine tool. A carefully designed structure can provide high

stiffness, result in higher operation bandwidth and more precise operation. The X-axis guiding

system will usually be smaller than the Z-axis rails, because they only have to carry the

weight of a small carriage and cutting tool, not the entire gantry. Gantry machines may have

one tool carriage or many tool carriages. Sometimes the tool carriages will each have their

own drive motor that moves them in the X-axis, and sometimes there will be only one motor

that drives the X-axis, and all of the tool carriages will be connected together by a steel band,

tie rod, wire rope, or similar mechanical device. The 3-Axis Micro CNC Machine is shown in

fig.5.

3.2. Specifications of Open Type 3-axis Micro CNC Machine

• X-Axis reach : 40 mm

• Y-Axis reach : 40 mm

• Z-Axis reach : 40 mm

• Total work space : 40,

• Power supply : 12 V 1 A

• Number of stepper motors : 3

Lakshmipathi Yerra, K. Chinnamaddaiah, Subramanyam B and P. Ravikanth Raju


3.3. Working Principle of Open Type 3-axis Micro CNC Machine

Computer numerical control machine tools are such type of machine tools that have

revolutionized machining processes. It is nothing but using a computer as a mean to control a

machine that produces useful objects from solid blocks of material. CNC machine works

under a close loop system that means when an operation is performed by executing a

program, a feedback is coming back to the CNC system. This is not a descriptive answer of

what is CNC machine. If we starts with a material block in a CNC machine after a certain

time machine gives us a finished product like a spur gear, rifle barrel etc. Thus we can see that

CNC machine performs various jobs in a single machine tool.

3.4. Parts of Open Type 3-Axis Micro CNC Machine

The following are the parts which are to be use in the development of 3-axis Micro CNC

Machine.

• Linear actuators : 3

• 12v 1A Adapter : 1

• Stepper Motor Drivers : 3

• Arduino : 1

• Extra Wire

• Motherboard mounts

• Various screws/nuts/bolts

• Soldering Iron

• Drill

4. EXPERIMENTAL SET UP

In the process of experimental set up the required mechanical components should be

mounting.

4.1. Assembling of Mechanical Components of Open Type 3-Axis Micro CNC

Machine

In assembling of mechanical components some type of casing to mount the motor trays onto.

Let’s start with the Y-Axis. The Y-Axis will go back and forth, so take one of the motor trays

and mount it parallel to the length of the casing close to one end. Make sure it’s aligned as

straight as possible and use some motherboard mounting screws to mount it.

For the X-axis mount it perpendicular to the length of another optical drive case, again

making it close to one end and aligning it as straight as possible. Then mount it using

motherboard mounting screws as well. As for the Z drive, we will need to mount it to the laser

housing sled of the X-drive. In order to do this, we need to find some way to extend and

create a platform to mount it to. In this system motherboard mounts and an electrical plate

covers are used. Then fastened the final motor tray to the electrical plate cover on the X-Axis

and also mounted another electrical plate cover to the laser housing sled on the Y-axis to

provide it a flat platform as well.

Once all of the drives mounted, the final step is to attach the X & Z axis to the Y- axis. If

the system wants to mount the X- axis perpendicular to the Y- axis (looks like an “L” shape)

and adjust them so that the Z- axis is aligned over the Y- axis. Scrub through each axis to

make sure none of them are overshooting or running into each other. After the alignment set,

screw everything together. The system ended up using an L Bracket, but you may be fine just

screwing one case directly into the other case.



4.2. Connecting the Electronics for Open Type 3-Axis Micro CNC Machine

To get everything wired up so that it works, we need 5 components:

• Arduino Uno : 1

• Easy Stepper Motor Driver : 3

• PC Power Supply : 1

The Arduino Uno is the device that will be controlling everything. It is essentially the

“brains” of the device. But by itself, it has issues controlling the stepper motors directly. To

resolve all Arduino/Stepper motor issues, it will need a “Stepper Motor Driver” for each

motor (in this case, will need 3). The Arduino Uno is shown in fig.6.

5. SOFTWARE INSTALLATION

At this point, all the hardware should be completed. The only thing that’s left to do now is to

install the software that will make it run. The CNC machine runs off of a programming

language called G-Code. It essentially tells the X, Y, and Z axis which specific coordinates it

needs to go to. By itself, Arduino has a difficult time interpreting G-Code, so we will need to

install a G-Code interpreter program called Grbl. Here are the steps you need to take to install

Grbl on your Arudion (Uno).

5.1. Grbl

Grbl is a free, open source, high performance software for controlling the motion of machines

that move, that make things, or that make things move, and will run on a straight Arduino. If

the maker movement was an industry, Grbl would be the industry standard.

Most open source 3D printers have Grbl in their hearts. It has been adapted for use in

hundreds of projects including laser cutters, automatic hand writers, hole drillers, graffiti

painters and oddball drawing machines. Due to its performance, simplicity and frugal

hardware requirements Grbl has grown into a little open source phenomenon.

Grbl is a no-compromise, high performance, low cost alternative to parallel-port-based

motion control for CNC milling. It will run on a vanilla Arduino (Duemillanove/Uno) as long

as it sports an AT Mega 328. The controller is written in highly optimized C utilizing every

clever feature of the AVR-chips to achieve precise timing and asynchronous operation. It is

able to maintain up to 30 KHz of stable, jitter free control pulses. It accepts standards-

compliant g-code and has been tested with the output of several CAM tools with no problems.

Arcs, circles and helical motion are fully supported, as well as, all other primary G-code

commands. Macro functions, variables, and most canned cycles are not supported, but we

think GUIs can do a much better job at translating them into straight g-code anyhow.

List of Supported G-Codes in Grbl v0.8c Master:

• Non-Modal Commands: G4, G10L2, G10L20, G28, G30, G28.1, G30.1, G53, G92, G92.1

• Motion Modes: G0, G1, G2, G3, G38.2, G38.3, G38.4, G38.5, G80

• Feed Rate Modes: G93, G94

• Unit Modes: G20, G21

• Distance Modes: G90, G91

• Arc IJK Distance Modes: G91.1

• Plane Select Modes: G17, G18, G19

• Tool Length Offset Modes: G43.1, G49

• Cutter Compensation Modes: G40

• Coordinate System Modes: G54, G55, G56, G57, G58, G59

• Control Modes: G61

• Program Flow: M0, M1, M2, M30*

• Coolant Control: M7*, M8, M9



• Spindle Control: M3, M4, M5

• Valid Non-Command Words: F, I, J, K, L, N, P, R, S, T, X, Y, Z

The software GRBL is shown in fig.7.

5.2. Flashing Grbl to Arduino UNO

Flashing a hex file to your Arduino is simple with windows. First, plug in your Arduino into

any USB port of your Windows machine and then determine the assigned COM port of your

Arduino.

To Determine your Arduino's COM port:

• Windows XP: Right click on "My Computer", select "Properties", select "Device Manager".

• Windows 7: Click "Start" -> Right click "Computer" -> Select "Manage" -> Select "Device

Manager" from left pane

• In the tree, expand "Ports (COM & LPT)"

• Your Arduino will be the USB Serial Port (COMX), where the “X” represents the COM

number, for example COM6.

• If there are multiple USB serial ports, right click each one and check the manufacturer, the

Arduino will be "FTDI".

To flash a grbl hex to an Arduino:

• Download and extract XLoader.

• Open XLoader and select your Arduino's COM port from the drop down menu on the lower

left.

• Select the appropriate device from the dropdown list titled "Device".

• Check that Xloader set the correct baud rate for the device: 57600 for Duemilanove/Nano

(ATmega 328) or 115200 for Uno (ATmega 328).

• Now use the browse button on the top right of the form to browse to your grbl hex file.

• Once the grbl hex file is selected, click "Upload"

After clicking upload, you'll see the RX/TX lights going wild on your Arduino. The

upload process generally takes about 10 seconds to finish. Once completed, a message will

appear in the bottom left corner of X Loader telling you how many bytes were uploaded. If

there was an error, it would show instead of the total bytes uploaded. Steps should be similar

and may be done through the command prompt.

6. CONTROLS OF MICRO CNC

• Using the Arrow tool (from top left toolbar), select your entire image.

• Move it to the bottom left corner of the grid.

• You can pan around the grid by selecting the Hand tool from the toolbar. Use it to drag the

image back to the center of the screen.

• From the upper right corner of the page, change the measurements to cm.

• Using the scale option from “Edit > Scaled Selected”, scale the object down and move it so

that it fits within the single square that is in the corner of the grid (use the picture to the left as

reference).

• With the image still selected, go to “Cam > Follow Path Operations”. Change the target depth

to -1, the safety height to 1 and the step down to 0.1 and then click OK.



• Then go to “Cam > Calculate Selected” to calculate the path.

• Lastly, go to “Cam > Export G-code” to save the G-Code of your image.

7. RESULT AND DISCUSSION

The open type micro CNC system is completed by integrating stepper motors to arduino

through the stepper motor drivers .Now the software GRBL is uploaded to arduino chip which

is controlled by GRBL controller by the help of which we can send G-codes. The G-codes are

the cause of the motion of the stepper motors which cause motions in X, Y, Z -axes

respectively. The Micro CNC is shown in fig.8.

8. FIGURES

Figure 1 Micro CNC system block diagram

Figure 2 Automatic Tool Changer

Figure 3 CAD/CAM Software



Figure 4 Display unit

Figure 5 Mounting of 3- axis Micro CNC

Figure 6 Arduino Uno

Figure 7 GRBL



Figure 8 Micro CNC

9. CONCLUSIONS

The high spindle speed reduces the chip load which reduces the forces between the tool and

the material. A high-speed / low-force machining yield less heat, reduces tool deflection, and

allows machining of thinner walled work pieces. This results in cooler machining, superior

surface quality and better accuracy. It is used to drill small and highly accurate holes which

are becoming a common requirement across a range of industries and applications.

REFERENCES

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machining centers,‖ Journal of Manufacturing Systems,1991.

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Journal of Modern Engineering Research (IJMER) (Vol.2, Issue.1, Jan-Feb 2012)504-508

ISSN: 2249

[3] V.K. Pabolu and K.N.H. Srinivas, "Design and implementation of a three dimensional

CNC machine",2010.

[4] T. Andrei and I. Nae, did the workout on "Practical applications performed by a stepper

motor CNC router", 2010.

[5] P.A. Sherring da Rocha Jr., R.D.S. Souza, and M.Emilia de Lima Tostes, "Prototype CNC

machine design", 2012.

[6] M. Karthick, M. Sundarraj and T. Raja, Design and Control of ATC for Shorter Time

Interval in CNC Machines. International Journal of Mechanical Engineering and

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[7] Mufaddal A. Saifee, Dr. Usha S. Mehta, Design and Implementation of 3-Axis Linear

Interpol Ation Controller in FPGA for CNC Machines and Robotics. International Journal

of Advanced Research in Engineering and Technology (IJARET), Volume 5, Issue 9,

September (2014), pp. 52-62

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