View Full Version : Looking for an CNC xPro controller board

04-02-2015, 03:56 PM
I'm in the process of building an OX cnc router from Openbuilds in America, but didn't purchase the control board at the same time as they were out of stock. I have since bought a Synthetos gShield (grblShield) V5 from Adafruit which I received damaged in transit. It was sent in a jiffy bag with bottom pins sticking through the bag and when I opened it all the top pins were bent to one side.

Adafruit saw the error of their ways after I photographed the bag before opening it showing the pins sticking out and another when I'd opened it. They refunded the cost of the board and the UPS costs.

They wanted to replace the board but I said no as I'd have to pay another 25 for Customs import charge.

Anyway I'm looking for an CNC xPRO control board (see attachment) from either a UK or a European supplier. I'm fed up with Customs pouncing on me every time I buy something abroad.

I'd be grateful for any help with this inquiry.

Thanks a lot.


04-02-2015, 10:39 PM
Is the gShield not repairable?

I'm not 100% certain this is possible at the moment but have you thought about using the Arduino with GRBL firmware to connect and drive external stepper drivers. I've got 3 Leadshine AM882 drives connected to a Arduino Uno at the moment, just for test purposes. I can drive them with code from the Arduino. This weekend I will try to drive them with the GRBL firmware and the GCode sender software. If you can wait that long I'll let you know if it works.

04-02-2015, 10:58 PM
Hello Ian
I know this works as I've seen Mark Carew setting up his router with this same configuration.

Watch it here (https://www.youtube.com/watch?v=8JufQ-xCvdg):

The shield is connected to the Arduino but I have yet to connect it up to power.

05-02-2015, 08:51 AM
Isn't he using the gShield in that video though? I'm thinking about not using a gShield but connecting the AM882 drivers directly to the Arduino with the GBRL firmware.

05-02-2015, 10:09 AM
Never heard of it done that way before.

Let me know the outcome if you survive the raging inferno won't you.

Best of luck.

05-02-2015, 10:43 AM
Seems a bit pessimistic! The AM882 claims to have TTL-compatible opto-isolated inputs, which sounds fine to drive with the ATmega chip on the Arduino board. Why put something else in between, unless it happens to make connections easier? Assuming it's a Uno board with a plugin cpu, worst that's likely to happen (and even then only as a result of a fairly significant fault elsewhere) is making the ATmega chip go pop. A 328P costs about 3, which is less than a typical breakout board!

The idea of cheap hardware plus open-source software giving better-than-PC performance for a fraction of the price of the cheapest motion controller is very attractive, and I would like to follow this one and hear how it goes.

05-02-2015, 01:10 PM
OK mate
Was a bit over the top. But I'll stick with the GShield as its all I've got at present.

05-02-2015, 04:58 PM
Ah, just done a bit of checking. I had assumed that the gshield was some kind of stepper driver interface. I now see that is a stepper driver card, aimed at lower voltage/power steppers than something like the AM882.

I'm not sure if your gshield is working, once the pins were straightened. If you have one of those in working order, then do you really need a whole new controller plus stepper drivers? Could you not use a cheap Arduino board to run grbl, and connect it to the gshield? I think grbl runs OK on an Arduino Uno, about 20 from Amazon. You would end up with something that's pretty well equivalent to the CNC xPRO, as far as I can see.

05-02-2015, 05:17 PM
I was going to do it that way because I'd straightened the pins underneath the board so it connected to the Uno. I'll try it out on my desktop over the weekend and let you know the outcome.


05-02-2015, 10:22 PM
Yes, only suggested the AM882 if the gShield was kaput but as it looks like it might be working OK I'd go with that.
The Arduino can certainly control the AM882, I think the drawback will be the speed of the 328P. I'm hopefully going to be trying it out with the GBRL firmware on a UNO this weekend. At the moment I have no intention of using this set-up in a final machine build, it's really just an experiment to see what the little Arduino can do.

Boyan Silyavski
05-02-2015, 10:33 PM
I'm fed up with Customs pouncing on me every time I buy something abroad.

I'd be grateful for any help with this inquiry.

Thanks a lot.


Hi Mike,
The customs here in Spain pushed me. So i push now all people i buy from. "Please could you state it lower than 20EU?", that before buying / or i don't buy from you :anonymous:/ . And it works. I wonder why i have never done it before.
I buy ALL stuff i need from the net, so we are talking $$$$ here

05-02-2015, 11:48 PM
Ian - the grbl wiki seems to suggest that even the uno (328P based?) can get up to 30KHz, which is pretty good going. Quick back-of-the-envelope sums suggest that with a 5mm pitch ballscrew and 800 microsteps, a 16KHz pulse rate would give 6m/min. That's a pretty good performance per pound out of the little 328P chip and even in terms of absolute performance is close to what I get from my LinuxCNC machine. Be interested to hear your findings.

06-02-2015, 04:12 PM
Arduino Uno with GRBL firmware controlling 3 AM882 drives with 3 NEMA 23 steppers.

It's a first test but it seems to be working very well.

Oh, I know, I know excuse the crappy wiring !!!


06-02-2015, 09:52 PM
Good stuff. Any idea what kind of pulse rates you can achieve, and what kind of stepper rotation speeds that translates to with microstepping in place?

06-02-2015, 10:06 PM
No idea yet. Need to get into GRBL and work out it's settings. Micro stepping on the driver is currently set at 400. Will have another play around with it over the weekend.