Dimensions before & after calibration

[pizzapizza]

An issue I've ran into on occasion(more often as of late) is the off shift reporting dimensions(radially) of a keyway that are far out of tolerance. At this point I haven't done anything different besides calibrating at the start of my shift and I've seen nothing of the same issues. Is it possible for that particular probe to 'lose calibration' that quickly? Or is there another issue at play?

Also, I've double and triple checked the program and all values are correct. Any help/insight would be great, thanks!

[Douglas]

Try not calibrate for your first part and see of it makes a difference maybe... could they be not cleaning parts and probes or something like that too? Grab one they ran and rerun it that might offer clues too if time permits. First thing I suspect is dirt usually

[pizzapizza]

Yeah, as I was typing this post I realized I should of done a before an after.

[Douglas]

Can still give the suspect parts a visual for dirt stuck in keyways if radially undersize... give one manual inspection to confirm discrepancy

[pizzapizza]

Ah yeah, I see what you mean. I have a habit of checking and cleaning parts before measuring; I didn’t see anything on these.

[YGOLORTEM]

Is there a probe change involved? If so is it manual or DCC?

Also is the slot or key-way parallel to itself and perpendicular to the surface it is cut on?

I recently found a lot of bad parts that the slot insides tapered. When I checked it from the top with a pin it was within tolerance but when I slid the pin into the slot it was very much oversize. The 1st article inspector bought these off for production run only checking from the top of the slot. Engineering couldn't figure out why the CMM kept checking the size OOT so they brought it to my attention and that's when I discovered the taper.

[pizzapizza]

Worn out cutter and/or taper near point of probe is what my hunch is. Hard to be for sure; my adhd had me going somewhere else immediately after running part.

[pizzapizza]

Yes, probe is changed to measure keyway only. I’m unsure if you’re asking if the probe change is manual or dcc or if the program is. Regardless, probe change is manual, and the program is dcc.

[Matthew D. Hoedeman]

Yes, probe is changed to measure keyway only. I’m unsure if you’re asking if the probe change is manual or dcc or if the program is. Regardless, probe change is manual, and the program is dcc.

could have a 'wanker' putting the 2nd probe on incorrectly, as in, the 'triangle' lined up with the 'square' That fubars everything.

[pizzapizza]

Haha, I’d like to say not possible. But giving the benefit of the doubt has burned me too many times.

[YGOLORTEM]

Yes, probe is changed to measure keyway only. I’m unsure if you’re asking if the probe change is manual or dcc or if the program is. Regardless, probe change is manual, and the program is dcc.

Also, to add to Matt's comment, if the magnet is not properly stored and then thoroughly cleaned before the install there's a good chance that it's picking up debris and not seating properly.

Edited my above post to add some detail

[Matthew D. Hoedeman]

Also, to add to Matt's comment, if the magnet is not properly stored and then thoroughly cleaned before the install there's a good chance that it's picking up debris and not seating properly.

Edited my above post to add some detail

and another thing..... if this is not a TP20-type probe, if ANYTHING gets un-screwed and something new screwed in, then there IS no valid calibration of the probe.

[pizzapizza]

It’s a tp20; and I’d like to think the other shift cleans things as often.