[Lo...] Posted June 27, 2025 Share Posted June 27, 2025 Hello everyone, So I am inspect a few gears on Gear Pro, using a rotary table. And some of the readings from the CMM are incorrect. Over pin dimension, major and minor diameters are incorrect. I am getting as much as .0001-.008. Yes. one tenth to 8 thousandths. When measured with pins and micrometer the dimensions are correct. I have requalified the probes that I am using and double check and recheck my program. I know my part is stable and isn't moving. What am I missing? Thanks, Lou Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/ Share on other sites More sharing options...
[Ch...] Posted June 27, 2025 Share Posted June 27, 2025 Lou, have you posted a similar topic before? I have replied to similar posts many times, could be a number of factors : Probably R/T Qual on actual part, chuck/clamping, probe/probing area. Are flanks straight or modified/crowned, etc ? Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134453 Share on other sites More sharing options...
[Lo...] Posted June 27, 2025 Author Share Posted June 27, 2025 Please sign in to view this quote. Chris, that issue was due to a probe being to big to fit inside the root of the teeth. Have the correct now, but not sure what is going on. I qualify the RT and probes before running the parts. And flanks are straight and aren't modified or crowned. Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134459 Share on other sites More sharing options...
[Ch...] Posted June 27, 2025 Share Posted June 27, 2025 try putting an indicator on a diameter and a face , and see how part is running. Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134461 Share on other sites More sharing options...
[Ro...] Posted July 1, 2025 Share Posted July 1, 2025 What is the actual status? Can you share a result of profile, helix and pitch? Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134545 Share on other sites More sharing options...
[Lo...] Posted July 1, 2025 Author Share Posted July 1, 2025 Please sign in to view this quote. Chris, I was able to get the chuck within .0005 of an inch , and once I had the part clamped I was getting .004 of an inch. Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134575 Share on other sites More sharing options...
[Lo...] Posted July 1, 2025 Author Share Posted July 1, 2025 Please sign in to view this quote. Roman, I sent you message with some of the data. Thank you. Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134577 Share on other sites More sharing options...
[Ch...] Posted July 1, 2025 Share Posted July 1, 2025 Lou, Try this, try to manually indicate the part to run < .0002" (at least radially) and let me know if MOP changes any... Thanks, CR 1 Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134579 Share on other sites More sharing options...
[Lo...] Posted July 1, 2025 Author Share Posted July 1, 2025 Please sign in to view this quote. Chris, Thank you for the reply. I was able to work with it enough to get .0007. But my results are still coming in undersized versus measuring manually. Thanks, Lou Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134603 Share on other sites More sharing options...
[Ch...] Posted July 1, 2025 Share Posted July 1, 2025 Lou, ok this is interesting, so did results change from 1st run by a large amount? Have you double checked all of your numbers? is the PD or involute largely modified in any way? are you measuring at the PD? what if you try measuring at center face width (btwn tip and root), are results similar? If Roman has seen your results, he will likely have a solid solution soon. Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134609 Share on other sites More sharing options...
[Lo...] Posted July 2, 2025 Author Share Posted July 2, 2025 Please sign in to view this quote. Chris, No results did not change. But the dimensions actually got smaller. I have double checked the programs, I have even started over and rewrote new programs and nothing has changed. I have it set up on V-Circle-Center face width. Roman does have my results and more info. But believe me, I am open to listen to anything (almost anything HAHA) the frustration is real. I appreciate all the help and info I can get. Thanks, Lou 1 Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134647 Share on other sites More sharing options...
[Ch...] Posted July 2, 2025 Share Posted July 2, 2025 Lou, feel free to PM me some charts (or .act file) to review, or gear data block from dwg, and program if possible... Can this possibly be inspected for MOP on CMM with Gear Pro without R/T? for comparison, this will eliminate on potential source of error. (Use any face and dia from top). I imagine you have already tried another probe to rule that out. What type of machine / head are you using ? Link to comment https://qualityforum.zeiss.com/topic/23805-over-pin-dimension-not-correct/#findComment-134649 Share on other sites More sharing options...
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