I'm working on a spindle speed control for my Sieg SuperX3 (Grizzly G0619) and thought this would be interesting to other folks. From what I've heard, this same design could be used to control a Sieg C4 lathe, but since I don't have one I can't say for sure.
The spindle motor of the SX3 is a nice BLDC motor that is driven by the main power board mounted in the electronics bay. Plugged into the power board is a microcontroller card that reads the hall sensor signals coming from the motor, and generates switching signals to the three half-H bridge drivers on the power board.
This microcontroller scans the buttons on the front panel, and sends a periodic update to the LCD display. This is accomplished through a fairly simple serial protocol.
My plan is to make a new board that goes between the microcontroller card and the buttons/LCD. This board will monitor the buttons and pass them along to the microcontroller when it asks. When in remote mode, it would read an analog voltage (0-10V) and set the spindle speed by virtually pressing buttons and monitoring the numbers being send to the LCD.
So far, I've got a prototype wired up on a perf board and I can successfully communicate with the buttons and LCD. I can also read data coming from the power board, so it looks like all the pieces are in place. I just need to write a bunch more code and finalize the design. I'm then going to order some boards (let me know if you are interested). It looks like it'll cost under $100 for everything needed.
I'll post back with more details as I have time, and I'll be asking a few questions to get feedback on some design decisions before I finalize everything.
Cheers,
- Dean