This is getting really old.
Another couple of wasted pieces of brass. This time, trying to cut a 6-32 screw. Turned down a piece of .250 bar until it matched the outside diameter of a #6 screw. Set the motor to 150 rpm and the "first cut" depth in the wizard to .0001". Made the number of passes it set, and the the thing I have is not a screw.
The one on the left is the second try for the night, after the first one failed. The first one was a different screw up. I cut the outside diameter too large, using my machinery handbook. Then I measured that cheap, zinc-plated, $1 per pound screw at the top, re-cut it to the right diameter, and ran the threading wizard's output again. It looks more like a screw, but you can see each thread peak is quite wrong.
Questions: I'm using a live center - seems like I have to, because these things are well beyond the 2 or 3:1 aspect ratio that you need a center for. When I do that, it's hard to get much of a running start into the thread (letting Z accelerate). I have used about 0.1" beyond the screw end, but it's crowded there.
Oh, before I cut the thing, I sized the quarter inch rod down to .130 with my CNC lathe, running the motor at full speed, and the Z axis as fast as I dare. No problem. Every pass ended in the right place. So it's not the motor causing EMI getting into the controller box (seen that before).
How fast should the feedback pulse to Mach from the spindle sensor be? Should it be a tiny pulse (thin piece of tape) or is it just looking for the leading edge? What problems should I look for there? The motor speed display looks stable. It drops about 2 to 4 RPM when using 150 RPM, but Mach is supposed to handle that, right?
Bob