Added beaglebone black with wifi dongle and now it's wireless. All I needed to do was set the beaglebone black to start the serial port json server and wifi at startup. All that's required is plugging in the power and a way we go.

Thanks to Chilipeppr being so portable (it's browser based). I can even control the CNC from an ipad or smartphone.

Lastly I made the spindle able to be turned on and off in software with M3 and M5 commands.

I tried getting the external PWM spindle control going, but it seems the microcontroller on the spindle controller board has not been configured for it (on this model) :(. The PWM sent to the motor is controlled by this micro by looking at a voltage divider's voltage, who's value changes via the 5K front pot (used as rheostat). From what I can see, the divider is 6K to 5v and 5K rheostat (pot) to ground. The external PWM pin on the board looks to goes through a lowpass filter and to an analog pin on the micro. Despite the different frequencies and duty cycles I tried on the PWM pin, I can't get it to work. I'm thinking of adding a small PIC that can read the PWM signal from the TinyG and control a digital potentiometer (as rheostat). I might add a small switch on the from of the case to select which pot to use (software or manual control). Not elegant, but will work fine.