ShapeOko Limit Switches Update

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.


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