Desktop size CNC milling machine from scratch

Description

I have built a CNC milling machine mostly from hardware store parts. My machine is more than just a proof of concept; It is compact, easy to work with and surprisingly precise, with a accuracy of 1/20mm. The machine is precise enough for milling PCBs and strong enough for milling wood, plastic and soft metals. A comprehensive youtube series about my machine finished as well, see links in the details below.

Details

Part 1:
Part 2:
Part 3:
Part 4:
Part 5:
Part 6:
Follow-up #1:

Follow-up #2:

- work size: 160 x 160mm, Max. height: 25mm

- Milling-tool: Proxxon, 20000rpm

- typical milling speed: 1-5mm/sec

- max. jogging speed: 10mm / sec

- milling materials (tried so far): PCB, plastic, wood

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- Motors: 3x NEMA17, 1.7A, driving 8mm M8 stainless steel rods

- Stepper drivers: 3 x Big Easy Driver

- Power: USB-Hub for the arduinos and all other 5V devices, 19V 3.5A laptop power supply for the stepper drivers

- Control: two Arduino UNO; both can control the stepper drivers. One runs GRBL and can process G-code commands from the computer. The other one runs my own software and is attached to the keypad and the LCD. This arduino gives a live feedback of the machine position via the LCD, even when the other arduino took over the control.

Hardware-ToDo: Connecting the GRBL-Arduino to the border switches (was not yet necessary) but will be needed for auto-leveling

- Manual control software:

- Moving in X/Y/Z direction: different speeds and different distances. The movement can be cancelled all times. Smallest moving step is 1/20mm.

- External mode: Live-feedback of the movement controls from the GRBL arduino, Internal mode: Manual control

- Homing/max loop, present table (moving table to foremost position), border-switch test

ToDo:

- Memorize position when system is switched off (no idea yet how to do that)

- G-code based Bed level test and auto-leveling

Files

CNC_jogger.ino

Arduino-based software for manually controlling my CNC machine. Niew, slightly improved version (December 2016)

x-arduino - 25.80 kB - 01/07/2017 at 12:08

Download

analogKeypad.h

The header of the analog-keypad library used for my machine

x-chdr - 956.00 bytes - 07/24/2016 at 15:37

Download

analogKeypad.cpp

The .cpp of the analog-keypad library used for my machine

x-c++src - 3.00 kB - 07/24/2016 at 15:36

Download

numericDisplay.h

The header of the arduino-library for showing my position numbers

x-chdr - 569.00 bytes - 07/24/2016 at 15:36

Download

numericDisplay.cpp

The .cpp of the arduino-library for showing my position numbers

x-c++src - 3.74 kB - 07/24/2016 at 15:35

Download

Components

3 × NEMA 17 stepper motor, 1.7A

3 × Big Easy Driver stepper motor driver

3 × Stainles steel M8 rod

6 × M8 nut Hold the M8 axles in the bearings

3 × 5mm/8mm motor coupling

Discussions

cdpeeling wrote 12/06/2021 at 13:47

Hi I like the idea of making a CNC Mill as your project shows. I'm a retired toolmaker employed in the electronics industry. I'm trying to source the Stepper Motors, Big Easy Drivers and Arduino UNO but I am given various options for each part eg. Arduino Pro Mini 5V 16MHz,

3D Printer Big Easy Driver board v1.2 A4988 2A Phase Stepper Motor Driver Board etc Are the components you used anything special and if so could you please supply additional information. Many Thanks Chris

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julian wrote 08/15/2018 at 19:35

Saludos, felicitaciones muy bueno tu proyecto, tengo una CNC casera y he pasado el tiempo investigando cómo implementar una pantalla LCD a la máquina pero en los tutoriales que vi la información de cómo lo hicieron no la dan detalladamente, te doy gracias por tus avances , ....... pero veo que no subiste los esquemas de cómo conectar el TECLADO y la LCD, te agradecería si nos compartieras esta parte ... soy de Colombia- Sur América.

Greetings, very good congratulations for your project, I have a homemade CNC and spent time investigating how to implement an LCD screen to the machine but in the tutorials I saw the information of how they did it without attention in detail, I thank you for your advances , ....... but I see that I do not have the schemes of how to connect the KEYBOARD and the LCD, I would appreciate it if you would share this part with us ... I am from Colombia- South America.

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Kittisak wrote 06/13/2018 at 13:20

Hey bro .. i am just a beginner and new to this CNC machines....... anyway iam intrested in your project.. Currently i made a simple cnc plotter using NEMA 17 andd EasyDrivers with arduino UNO..... I am confused with the circuit of your machine......can u send me a image of your circuit diagram and i need to know what softwares are u using bdprint@gmail.com

Thank You

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joekutz wrote 06/13/2018 at 15:29

Most of my schematics are not needed when you just want to build a CNC-machine with arduino and GRBL, as all you do is connect the step- and direction lines of the three stepper-controllers to the corresponding pins of the arduino. My more complex schematics are only needed because I used a second arduino that has my own software for controlling the machine with the keypad.

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msraj.mech wrote 06/17/2017 at 14:12

hi can u please send me complete connection s diagrams to msraj.mech@gmail.com

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stissera2 wrote 08/13/2016 at 17:03

and bro iam previosly used a different code called (gbrl)

can i use that code and additonally with your LCD display files.......

help me with this....i really do not how to organise this out

Thank You (stissera2@gmail.com-My email)

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joekutz wrote 07/24/2016 at 15:40

Hi there! I added the source files for my project to the hackaday-page because people kept telling me that the download does not work. User Jaroslav here in the comments made a nice-looking version of the schematics, which can be found under https://postimg.org/image/nqzsqnazf/.

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subash796 wrote 07/24/2016 at 14:10

Thank You

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joekutz wrote 07/24/2016 at 15:41

See my last comment - my software is now directly under the "files" section.

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mickthomson21 wrote 07/14/2016 at 17:27

How are you!

Congratulations for the work done with the CNC , watching your videos on YouTube that I realized you shared the schematic of connections besides programming , try to enter http://joekutz.de/schematics_code_drawings.zip but it seems the page a fallen .

You could give me the information that you share in that file ? quite interested because I start building my CNC

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joekutz wrote 07/24/2016 at 15:42

I have put the software now in the files section of my project page.

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valo_hp wrote 05/08/2016 at 18:57

Hello, you can replace the ULN2803a at ULN2003 it

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joekutz wrote 03/02/2016 at 08:20

Alright, I updated the "files" section of my project, you can now find the most recent version of my Arduino-software and the test-pattern from my latest video. Cheers.

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joekutz wrote 03/01/2016 at 21:12

Hi all,

I added another follow-up about my machine, see youtube clip. Enjoy :)

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misa.zivanovic85 wrote 02/19/2016 at 19:13

Hm

Could you suggest where to buy Nema17 1,7A version?

Are these any good?

http://www.ebay.com/itm/Germany-stock-5pcs-Wantai-nema-17-56oz-in-1-7A-Reprap-bipolar-for-3D-printer-/221964767809

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joekutz wrote 02/19/2016 at 21:50

I got mine from Ebay as well, I guess it depends on where you are. The motors from your link seem to be pretty much like what I got as well.

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misa.zivanovic85 wrote 02/19/2016 at 12:48

I want to ask a noobie question.

Can i use Nema 17 with 1,5 A.

And what is different between Nema17 (1,5A) and Nema17 (1,7A)?

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joekutz wrote 02/19/2016 at 16:57

It depends on how you want to drive the machine. A shapeoko-type setup (pulleys and belts) needs stronger motors than my setup, or it will skip steps when on load. I run my motors at less than 1.7A, so 1.5A should be fine.

The difference is basically how much current the motors can stand thermally. A 1.5A nema 17 motors might also be a bit shorter than the 1.7A ones.

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deadpangold wrote 01/26/2016 at 15:05

At last I've managed to have a second look at your videos. Lots of people say that drawer-slides are not as straightforward as the look but yours is the best detailed description I've seen. As I couldn't be sure of what the problems were, I just avoided using them on my build.

Thanks also for the link to OpenSCAM (CAMotics). The latest version is a big improvement.

Can I ask how you attached your limit switches? I couldn't see the detail in the video.

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joekutz wrote 01/28/2016 at 11:23

You mean electrically? The input-lines are pulled down to 0 with a resistor usually and are pulled up to 5V when a switch closes. I used one line per direction with the switches put in parallel (most CNC systems support only one switch per border anyway).
Right now, only the my-own-software-arduino is connected to the switches, but I should connect the other one (running GRBL) as well. Within the GRBL configuration, you can set which pins are which borders and whether 0 or 1 should be recognized as "switch closed".

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deadpangold wrote 01/28/2016 at 12:35

No. Sorry. I meant how did you physically attach the limit switches. Is that self-tapping screws into the fibre-board? Or are there small nuts out of view somewhere? I'm trying to decide how best to fit limit switches to my machine. Whether to drill the aluminium or the fibre-board.? Something very adjustable (even clipped) would be good, initially at least.

I like your micro-switch guards. I'll do that too.

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joekutz wrote 01/28/2016 at 12:52

For the switches, I used 2mm metal screws in 1.5 mm drilled holes, so the screws tapped their thread themselves in the fiber board. The same holds for the 3mm screws that hold the protectors (2.5mm holes). I did the switch fine-adjustment with the counter-parts (that press down the levers) which are made of paperclip-wire, and which I moved to the correct position before tightening the (this time: wood-) screw.

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Jaroslav Kašpar wrote 01/10/2016 at 01:09

Hi, I really like your project. Very good job! To better understand the electronics you designed (I am not very good at it), I made the schematics in Eagle. I hope I understood, and made it correctly :) . Looks like this:

http://postimg.org/image/nqzsqnazf/

If you would be interested, I can send you the whole project including the PCB layout.

I have a question (please keep in mind, that I am less, than a beginner, when it commes to electronics). When the GRBL-arduino sends a pulse to step a motor, it triggers the two transistors, which makes a separate pulse go through the capacitor to the second arduino. I undestand that. But I am not sure, what ensures, that:

1st - this pulse does not trigger the transistors again. The circuit looks like it could... Is it the 5k resistor in the way? Or is the pulse just too "weak"?

2nd - this pulse does not "return back" and does not reach the motor driver? Is it also the resitor? (This time 10k)

Thank you!

Jarda

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joekutz wrote 01/10/2016 at 10:35

For "being less than a beginner in electronics", it is a very nice Eagle-schema. Seriously, looks like you have put quite some work in that. I would be interested in the PCB layout, could post it here with reference to you.

I must generally say that my "count steps" circuit works less than well, it actually misses counts when the mill jogs with high speed in a ca. 45° angle - logically, because the X/Y pulses come almost at the same time and the interrupt-based counter does not know whether a pulse was one or two pulses on different lines. I might post a youtube clip about that problem eventually. Also: The counting is less helpful than I thought, the keypad-control is much more important to me.

To your questions:
1: The pulse after the capacitor-resistor border is actually fed back into the input side of the ULN2803, but it is not a problem because the border does not let DC pass - so the pulse will fall to 0 quickly even with the "feedback". The input at the ULN must be 0 in between for the capacitor to discharge, only then a new pulse can pass.

2: The pulse also would reach the motors, yes. But there is no "low" between original pulse and the "second" pulse - so the stepper driver counts it correctly as one pulse.

Hope this helps, Look forward to a PCB scheme.
Cheers, joe

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Jaroslav Kašpar wrote 01/10/2016 at 17:31

Thank you!

Here are both files. The schematic and the PCB:

https://drive.google.com/file/d/0B0C3172PryBzeUtIeGY2UVR5dmM/view?usp=sharing

I was thinking, that the counting could be done somehow by logging the actions done by the GRBL-arduino and then reading the "log" by the second one. It would be slightly slower, but could be precise.

Jarda

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Jaroslav Kašpar wrote 01/13/2016 at 19:40

I changed the board a little (made it smaller).

https://drive.google.com/file/d/0B0C3172PryBzUFpUc09BUUFrdFU/view?usp=sharing
If there will be some problem downloading the files from google drive, please let me know, i can send it to you by e-mail. Mine is j.kaspar(at)centrum.cz

Jarda

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Joseph Lavoie wrote 12/18/2015 at 19:10

Looks great.

* Do you have a back lash compensation on your X and Y threads?

I use 1 mill end mill blades and have broken lots of them.

Joseph.

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joekutz wrote 12/18/2015 at 19:49

Hi! And thanks. What do you mean with back lash? Also: when you say "1 mill", is it 1 millimeter or one of these odd non-metric measures ;) ?

cheers, joe

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Joseph Lavoie wrote 12/18/2015 at 20:24

The wear of the thread needs to be compensated. I use a dial guage to measure the number of steps the thread turns before the bed moves. So when the motor changes direction the backlash is added. This makes the machine very accurate.

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joekutz wrote 12/18/2015 at 23:11

Ah okay. Right now, there is no noticable backlash (may be below 1/20 mm) , but it will come eventually I guess. When there is a setting in GRBL for that (or in whatever makes my G-code) I will try it out some time, thanks for the tip.

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Joseph Lavoie wrote 12/19/2015 at 02:07

Try to engrave a circile 3" in diameter. Look close at where the quadrents are this will tell how much back lash effects the cut. My machine is ten years old and the back lash is 12 stepper counts. 10 theads per inch thats very small amount out. I realy like the engraved circuit board idea too. Joseph.

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joekutz wrote 12/11/2015 at 20:25

I made a short follow-up clip that shows how my CNC machine is doing after some hours of operation. In that video, I also show some little projects I made with my machine. Enjoy! :)

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Rick Boekelo wrote 11/06/2015 at 13:01

Hi could you upload the 3D model

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joekutz wrote 11/07/2015 at 10:27

Hi! The 3D-model is within the .zip file I linked in the descripton.

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Rui Rex wrote 07/31/2015 at 10:23

The videos are great! Well done!

You´re right when you said some videos didn't focused on some important issues. Yours seem to do it fine.

Keep it up!

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joekutz wrote 07/31/2015 at 09:17

I have also linked the schematics and the software in the description now!

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Desktop size CNC milling machine from scratch

Description

Details