The limit switches seemed to be working great, and I was loving being able to home the machine and not have to re-zero my work all the time.
I even got some work done.
Then I tried to do some surfacing that used the YZ plane. Something about lots of Z movement made the limit switches randomly trip.
So I thought about it a bit, then I found some shielded 22 AWG 5 conductor cable for $0.33 a foot and rewired the whole machine.
I rewired both the limit switches and the stepper motors. It took a few hours and some messing about. As a bonus, the cable was thinner than what I had previously used and I got all four cables into the cable chain.
Interestingly enough when I tied all the shields and grounds together the limit switches tripped as soon as I moved the machine. I ended up tying the shield in the limit switch cable to the ground and left the stepper motor cable grounds tied together, but floating.
Now the machine works great and I have not had a false trip yet.
The next thing to investigate was the repeatability of the homing switches. The documentation for the switches says they should be repeatable to .012″. But I wanted to see what really happened.
So I put my dial indicator in the vice and set it up to zero on the end of dust shoe.
Then I homed the machine and sent it back to the same location. The indicator read .0005″ Hot damn.
I repeated the test about 10 more times, including turning off the power and doing a cold start. I was never off more than .0005″. Impressive, and much more accurate than I expected!
I’m very happy with the way the limit switches are working out. I should have installed them from the git-go.