Neil Yeager often lets his Sherline CNC mill run a job, but wanted to have the spindle motor shut off automatically when the cycle was completed and the Z-axis returned to the home position. That way if he didn't come back right away, the spindle motor wouldn't continue to run. He wired and additional on/off toggle switch into the line current and rigged it to be tripped by the raising of the headstock. He included a spring in the chain to dampen the movement. Here's what he had to say:

"I thought you might find this interesting. I looked around and didn't see anything like this on the market, so I made this device myself for my Sherline mill. The principle is simple, and I have this same setup to auto-stop my Lortone lapidary slab saw. Setup is pretty easy, and the idea is that for certain tasks you can set up your CNC mill, adjust the final Z setting and then walk away to do other tasks. The auto-stop turns off the drill head when the job is complete. I'm using a millimeter mill, so I adjust my final Z stop to be 20 mm. The initial starting point for the Z is 6 mm.

I am thinking of making these units for other machinists. It probably could be adapted to work on other types of machines as well."

Neil Yeager, Myrtle Beach, SC