How to wire an arduino-based 3-axis CNC machine

I've seen a number of tutorials about how to build the platform for a 3-axis CNC milling machine.  I have not seen anyone tackle the tricky subject of the electronics.

Here now is my attempt to do so.

Step 1 Parts

You'll need:

- an arduino. I chose duemilanova. (depends on the board you get)
- 3 stepper motors.  I chose NEMA 17s . ($15/ea)
- 3 EasyDrivers from Sparkfun . ($15/ea)
- some Cat5 ($2?)
- a 12V power supply for the steppers ($5?)
- a soldering iron
- some electrical tape
- an optional female plug is not a bad idea (<$1)

TIP: Don't get a 6ft or 10ft Cat5 cable.  Buy your cat5 by the foot from any computer or electronics store. That stuff has one wire inside instead of lots of little fibers.  Little fibers are a huge pain to work with. 

Comments

[muhsien5806]

Sir
I've copied and pasted this code into an Arduino sketch, but when verifying, I get an error message that "easydriver does not name a type". How do I rectify this?

[aggrav8d]

I can't imagine how you are getting that error. Are you sure you've copied it correctly? You may have a problem with line endings.

[niksa77]

(removed by author or community request)

[aggrav8d]

650ma maybe too low for one motor. Check rating. NEMA17 need peak 2A.

[niksa77]

(removed by author or community request)

[bufalloo]

I'm still confused. I'm having trouble finding how to interpret G-code to the stepper drivers. If possible, could you give me some pointers on how to find some sample code to do this? For example, could this be configured to be used with replicatorg for 3d printing?

[aggrav8d]

http://www.instructables.com/id/100-Mural-drawing-robot-also-works-as-a-giant-et/

open source code for this other tutorial does it.

[acl9865]

Hey,
When I bought my arduino it came with a 9v wall wart. I have a variable DC power supply at home, what voltage would you recommend supplying to the Nema 17's?

[aggrav8d]

ask whoever sold you the NEMA17s. I run two of them for my latest project at 12v2a with no trouble. I'd guess 12v and 1a for each.

[acl9865]

Ok thanks. Did you end up building a frame for yours? I'm trying to find the most cost effective way of providing linear motion. Rack and pinion is pricey, all thread gets mixed reviews. Would you recommend 1 motor on each side of my longest length to prevent binding from one side being powered while the other isn't?

[aggrav8d]

I would ask the real CNC experts at CNCZone.com, they'll know a lot more than I would.

[happytriger2000]

Hi,
I'm getting this "avrdude: stk500_getsync(): not in sync: resp=0x00" right after uploading it to my Arduino Duemilanov, what does it mean?, is the uploading completed fully?

[aggrav8d]

"The most common cause of this error (IMO) used to be people choosing the Duemilanove 128 when they had the newer Duemilanove 328. Click on -> and make sure you have the right board chosen, and try again."

-- http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1248528012/all
-- http://www.google.ca/search?q=avrdude%3A+stk500_getsync%28%29%3A+not+in+sync%3A+resp%3D0x00&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

[happytriger2000]

Hiya,
I took a screenshot of the chosen borad = arduino Duemilanove w/ AT328, opent attachment.
Actually I was looking for the Gcode interpreter code, but not sure if the above code is the right one. I want Arduino to accept Gcode and run the Stepper motor. I have a Arduino borad, a PMDX 122 board 3 x 3phase stepper Driver w/ Motor, power supply ready, and the code which I haven't figure out yet.

thanks

[happytriger2000]

Oops, the code provided was only a sample code to run stepper motor, sorry my fault.

[kotten]

If someone made it this far, it means that they now can control the stepper driver with Ardunio but Ardunio doesn't yet know how to interpret G code? If that is correct, then the next step would be to install a GCode Interpreter in the Arduino Library, such as mentioned here: http://reprap.org/wiki/Arduino_GCode_Interpreter.

Are you aware of Grbl http://dank.bengler.no/-/page/show/5470_grbl?ref=mst
or http://www.contraptor.org/arduino-gcode-interpreter. And how do they relate to what you are or have done?

[Electronics Man]

So if I would use the shield on this website--

http://www.adafruit.com/products/81

Do you think I could still use the codes you used for your arduino?
And also what software do you use to create the designs? Have you ever heard of Goolge Sketchup? I was wondering if I could use that to create my designs then send them to my arduino.

[aggrav8d]

I haven't used that shield. Send me one and I'll tell you for sure ;)

I use Alibre, but I don't like it. Sketchup would probably be great if I could get used to it. I'd really love to get SolidWorks so I can run FEA on the parts I make.

You don't really need to "send the designs to [your] arduino". As long as you know the important measurements (the ones you use to build your computer model) that's enough.

[Electronics Man]

So can you help me with the software? I dont know which ones are compatible with the arduino and my motor shield I bought here-->

http://www.adafruit.com/products/81

And also could you help me design a carrige for the Z-Axis that uses a servo instead of a stepper?

Thanks!!!!!!!!!

[bbyrd1]

It might help you to examine my machine. There's a complete wiring diagram there too. Of course, your project may require a different approach. And yes-- you can use SketchUp. I speak to that on my site too. www.ProDrawer.com

[Electronics Man]

I hate to ask such a stupid question but can someone please help me out with stepper motors? Do I need on with 4 wires coming out of? it if so what do each of the wires do? And could someone please suggest a good place to buy them?

[aggrav8d]

Depending on the model you get, some have 4 and some have 6. As I understand it, each one controls a different set of magnets inside the motor and by switching power between them you can make the shaft move in very small increments. I don't know where you are in the world, so the only suggestion I can make is shop around online. ebay will probably have the cheapest option. (Watch for crazy shipping fees!)

[Electronics Man]

thanks! Have you thought of trying to use this shield?---

http://www.ladyada.net/make/mshield/use.html

[aggrav8d]

I haven't. I had not heard of this model before. Try it and let us know how it goes.

[cfrancke]

agrav8d you say you need a 5v power supply for this project, but didn't you say the Nema 17 needs 12 volts? I'd like to run a nema 17 1 axis with an arduino but not sure what power supply to use for the Nema 17 stepper motor. Any help, links would be MUCH appreciated!!

[aggrav8d]

Thank you for catching my typo. Originally I got the steppers spinning with 5v. Under load you'll want to give them the full 12v. Also check your amperage!

[90mp11]

Variable voltage power supplies are good for driving motors. I've just built the electronics for a 3 axis CNC and the variable power supply from Active Robots (UK) let me run them at a low voltage for testing, so I don't blow my EasyDriver boards on the firsty run

[bac512]

I was just looking through an old printer to scavenge parts from, and I notice has 2 stepper motors, but only 1 stepper motor driver.. which got me to thinking, the CNC machines DONT operate MULTIPLE steppers at once, do they? don't they basically move all x, move y, then move z (or so other order, but, complete to the point). Would it cheaper/easier to build a switching circuit to switch the steppers in and out of the stepper driver, so you'd only need 1 driver, 1 arduino, and 1 switching circuit? and that circuit could probably easily handle 3, or even more for the really fancy machines?

[gunnk]

Not sure what kind of circuit you have in mind, but remember that you'll need to keep supplying power to each stepper at all times. Steppers only provide holding torque when powered, so you'll get all sorts of slip if you cut power to them (especially if your machine has any kind of rotating bit on it).

[bac512]

hmmm... ok, even more reason not do use only one driver :)

[willrandship]

Well, if you can keep it powered while switching, you might get away with it.

[aggrav8d]

You'd get less accuracy than running them all at once. If you move X and Y at the same time you get a diagonal line. If you move X and THEN Y you get a square shape. The difference is probably tiny. I say try it and let us know how it goes :)

[bac512]

thats true, I wasn't thinking things through completely. BUT, it COULD be useful in other things (robotics?) that used multiple steppers to make it cheaper. (again, yeah, less accuracy, but, for something that didn't need THAT MUCH accuracy....).....
yeah, unfortunately, i don't know enough about electronics to know how to design the circuit....

[90mp11]

The only problem with that approach is that you would quickly wear out a switching circuit, as it would have to switch hundreds of times to form a diagonal, or arc line, of which many projects are built.

I like the idea in essence, and for a 2.5 axis engraving machine, this would be ideal, but for a 3 axis, you'd be making more work for yourself, and creating more cost in the upkeep to keep replacing components that burn out on the switching circuit.

[aggrav8d]

transistors and resistors are your friend. Look at http://www.youtube.com/watch?v=Fc3R1SP5Ykw for a simple example of how to design the circuit you want. Since the NEMA17 steppers are 12v, you don't have to change much.

[bace1978]

hello everybody here
i bild this stepper motor driver bord with a arduino uno
with te demo code it runs fine it was fun to bild
now getting it to work with a cnc software is the next step en bilding a cnc frame
gr bramco from the netherlands

[aggrav8d]

You will have a few challenges:
1 - process move instructions from user
2 - move in a straight line (have to time the motors correctly)
3 - move in an arc. Assume a circle with start, end, center, and direction (cw or ccw)
4 - write PC software that converts designs into arcs and lines, then
5a - sends them one at a time to the arduino
5b - the arduino reads those instructions from an SD card like MakerBot does.

I have done 1, 2, and 3 for my Delta3 and Stewart Platform robots.

Good luck!

[HeilandStark]

Hi Dan,
thanks a lot for this instructable. I just find out the same Easystepper drivers but I'm not sure I can use with this board I've bought on ebay: afishonaladder.com/docs/5_Axis_Interface_Board_adapter.pdf
I have 3 stepper motors scavanged from an old copier and I'll buyt the same 5V power supply you suggest.
Hope I could work with this board and keep going into the project.

Thanks a lot for your advise.

HS

[aggrav8d]

You can use a higher voltage power supply if that's what's needed for your steppers. Be aware that the higher you go, the more heat will be generated in the chip. I've heard that some people put CPU heat sinks on their chips to keep them from automatically shutting off.

[HeilandStark]

thx but what I'm not sure about is if the board is compatible with the Easystepper drivers.
Thx
HS