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Homebrew Cnc Machine (for Cutting/engraving)

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kd8wdave

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Mar 5, 2013
Messages
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Hi all, Have not posted much. Usually don't as others do a better job than I in most cases.
I have built from scratch a CNC simple machine. Here's what it looked like with the 'old dremel tool' I've had for 50 years as its spindle drive. Further down you can see the new spindle mounted.
CNC-Overview.jpg
The 'frame' is 1" black-iron pipe. The X & Z axis are my creations, and the Y-axis is a commercial guide given to me by a neighbor. My X & Z axis are 20 TPI 1/4-20 thread rod. Not the best threadrod, just what you can get from any hardware store. The Y axis is 4.25 TPI commercial guide with ball-bearings. The basic configuration is a Desktop(via USB port) downloads the 'g-code' file to the ARDUINO-UNO control module mounted on the vertical board on the rear of the CNC frame.
The "Z-axis" stepper controller & Dual H bridge driver are shown below.
ZAxis-NewCard.jpg The Arduino generates STEP/DIRECTION commands to each axis based on the 'g-code' passed. These commands are passed to three 'controllers' which I made. These controllers take the step/direction commands and converts them into a parallel string (4 bits wide) in a timing pattern that goes to the dual-H-bridge drivers , which in turns sends the pulses to actually drive the stepper motors. The 'Grbl' software handles the acceleration/deceleration functions, based on all of its 'tuning' parameters. [I only use the FULL-STEP mode as the stepper mode, because it gives the maximum torque!] My steppers are 1.8 deg/step or 200 step/rev, and the axes are 20 TPI and 4.25 TPI. The controllers use a PIC16F628(A) microprocessor as the control interface and the PIC software is written in assembler. I had some issues with electrical noise using my old dremel tool, but have been able to eliminate the noise issues with primarily software in the PIC's. All three PIC-boards are identical so far, so only one program to maintain for these.
I have the new spindle mounted and I really like the way it works. The design allows me to change spindle heads if I need to (aka a bigger one later!).
I am a retired(72 yr old) guy who used to work in process-control and networking in a steel mill. Now I spend time on my lathe, this machine and 'amateur radio' such as the wife puts up with me.

cheers

Was not sure where to put this, so just added to end of this one.
Here are a couple of pics showing the new spindle motor mounted on my machine.
Found out I can drive this as an AC or DC . Now I'm using a simple 'household' triac wall switch to control the speed. I have not yet put in a switch for the Arduino to turn it off/on, because my 'Grbl software' doesn't provide variable speed, but does provide ON/OFF only.
Just been lazy getting the ON/OFf working.

Spindle 002.jpg
Spindle 001.jpg
I have found I can generate appropriate 'G-code' using a program called 'Inkscape', Open Office spreadsheet and some small amount of editing. I think its important to realize that the size of stepper, the material being cut, the type of cutting bit, machine size, all will affect the capability of the machine. I run my machine at slower speeds than normal, which is okay for me. I want it to run without missing OR acquiring any additional steps needed. I'm not familiar with any of the commercial CNC products, as I built my own system. I believe the controllers I built are capable of handling any stepper because they simply supply the full wave pattern to the 'H-bridge' controllers. Only increasing the motor size substantially would require me to change 'H-bridge ' units.

Feel free to ask/comment on any thing pertaining to this system.

kd8wdave
 
Last edited:

Hidyn

Active Member
Registered
Joined
Nov 4, 2015
Messages
42
This is absolutely outstanding and I love it! Well done!

I'm building my own as well, but I'm spending the extra to get professionally made and programmed stepper drivers. I know that when I complete this project, there will be a LOT of trouble shooting, especially with the software, and I wanted my drivers to work, work well and work right out of the box.

Software is the hardest part for me and I heartily commend you on doing a lot of it yourself. Personally, building code from scratch for a project with this many other variables is beyond me.

Once again, congratulations on a job well done!
 

kd8wdave

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Mar 5, 2013
Messages
19
This is absolutely outstanding and I love it! Well done!

I'm building my own as well, but I'm spending the extra to get professionally made and programmed stepper drivers. I know that when I complete this project, there will be a LOT of trouble shooting, especially with the software, and I wanted my drivers to work, work well and work right out of the box.

Software is the hardest part for me and I heartily commend you on doing a lot of it yourself. Personally, building code from scratch for a project with this many other variables is beyond me.

Once again, congratulations on a job well done!
Appreciate the compliment, Thanks
 
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