Here's a discussion on using bCNC with Raspberry Pi: https://github.com/vlachoudis/bCNC/issues/12
The basic gist is that unless you're torture-testing the machine, a Raspberry Pi 2 can handle what it needs to.
1) Setup the Raspberry Pi according to Chamnit's comment in the thread above. Most of that is pretty standard if you've ever used a Raspberry Pi. If you haven't, take a look at the adafruit tutorials - https://learn.adafruit.com/adafruit-ras ... i/overview
2) Once you're at the point that you're booting into a GUI, set up the network. Even if you don't plan on using a network with it in its final location, it makes everything easier because if you need to update it, you can bring it into the house and plug it in without a monitor or keyboard, and control it from your laptop.
3) I originally used the bCNC distribution that was linked in the thread above, but a) I don't see it there any longer. b) I never had luck making it work. I think the latter is because bCNC didn't understand the tool change commands and defaulted to running in a safe mode.
4) Make sure that the pi user can access the serial port - at a terminal, type:
5) I'm running universal G-Code Sender from here - https://github.com/winder/Universal-G-Code-Sender
6) Once that's installed shut it down, bring it to the shop and plug it all in. USB from the CNC machine goes into the usb port of the Raspberry Pi. I have an external monitor and the aforementioned keyboard/mouse combo.
I work on the CAD / CAM on my laptop in the basement and copy it via the network to the PI. Note on microSD vs. USB storage. The PI boots off of the microSD. Although there is a small FAT boot sector, you're not really going to use that for storage. You should put your files on a usb drive if you don't have a network.
With the file on the Pi, I power on the Shapeoko, open UGS and connect to it on the default serial port. I have limit switches enabled which requires me to home the machine before I can jog it. I home it with the built-in button, then jog it into position or use a macro to go to a pre-determined workspace coordinate system (G54-G59).
I use another macro (http://www.shapeoko.com/forum/viewtopic ... 15&p=50198
) to zero the Z-Axis with a touch plate (just a piece of brass plate I measured with calipers). The touch plate and end mill are connected to the control board with alligator clips provided with Additive Aerospace's limit switch kit: http://additive-aerospace.myshopify.com ... -probe-kit
With all of the coordinates and workspace set, I pick the file in UGS and send it to the machine.
Let me know if you still have any questions. Glad to help if I can.