Self centering small threaded holes

[[Ri...]]

Robert, you are correct but there is a "Minor" designation that can be applied.

[[Br...]]

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This is interesting. So do you use any filtering or outlier elimination? In all my own personal experiments, I've had better luck with the helix on the pitch for location than the line scans. I have really seen some problems with repeatability concerning the line scans on shorter thread depths. Maybe my methods on the line scans aren't ideal. I usually don't filter or eliminate outliers when this is done, and I use Least Squared.

[[Ri...]]

I used Filters, 50 UPR Low Pass Spline and Outlier Elimination 3 Sigma Inside and Outside with 2 Adjacent points and 3 Iterations. I did not test High Pass Spline filter for this but I did testing with Pre-Filters for Outlier Elimination and didn't see an impact on the Outliers. The critical setting is the Cylinder evaluation, Max Inscribed must be used. 6 lines is my minimum and 500 points per line. Measure and check with a gage pin. Slower than normal speeds and as large a stylus diameter as is practical will help. What is key to this is testing. You have to run a routine, change something and run it again. All the thousands of characters I've typed in on this forum could be absolute nonsense. Once you learn something via testing on your machine, in your environment, on your parts, with your stylus systems, you can take that knowledge to the bank. I know it's difficult finding time for this. Time is money after all. What you have to ask yourself is, "How much does the wrong answer cost?"