Passive Probe calibration

Anyone have any ideas/tips on calibrating the Tormach passive probe? I’ve opened a ticket but in the meantime thought I’d throw it out there. I can only get it to within about .002-.003 in. concentric that doesn’t seem good enough.

I am finding the set screws are very tight in the housing, one of them was so bad I had to drill it out and chase the threads. Did anyone else have issues and overcome them with this probe? I’m sure it’s me but hoping someone has insight.

Mine was tight but not that tight. Should be able to dial the concentricity within a tenth if everything is working correctly. The ABC method in Path pilot should be all you need. Always triple check that the probe tip is finger tight. If you’re screwing 1 of the 3 screws in, make sure you loosen up the the others a hair or 2 first. Leave the gorilla wrench at home. Make sure scale axis and backlash are dialed in before probe set up. Use a master ring gauge to set the tip diameter.

Not sure how helpful any of that is(probably all old news to you) but that’s just about everything I know about the probe and it’s set up.


Finally got it with the help of support. I ended up having to run a tap through 2 of the 3 set screw holes (that wasn’t suggested by support) this way I could tell if it was binding against the shaft or in the threads. Next, I had to really concentrate on VERY small adjustments as I got close. I also ended up using a dial test indicator rather than the built-in function in PP.

Final outcome double checked in PP:

It just takes forever and the closer you get to 0 the more tedious and frustrating it gets. I don’t have the active probe but I’m pretty sure it’s the same game either way. Takes me about 2 hours to center mine to .001mm +- .001 that includes cleaning the spindle surfaces.

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Just weighing in to say the same thing - you absolutely have to be loosening the opposite as much as tightening otherwise you’re just bending the ring. It takes a while but once it’s set up ours has been very consistent.

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Have you checked it again after using it a while (assuming you haven’t manhandled, dropped, or crashed it) and is it holding to the same calibration?

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I managed to adjust to within 0.0001” (two values the same and one value plus 0.0001 with the Tormach metrology kit (virtually no needle movement) and then checking against PP probe function.

I found it was off about a week later.

As I was adjusting, I found the tip was loose.
Should have tightened it and then rechecked first.

Lesson learned. :man_facepalming:

I guess one needs to keep an eye on that and check it first before looking for that hex key…

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I have not but it’s a good idea, I will today!

I went back and checked and sure enough it was out by over .001. Got it back to within .0005 but need to spend more time on it to get better than that! Good tip to go back and recheck.