Help measuring small threaded holes....scanning too fast error or air scanning...

[[Du...]]

I keep getting scanning too fast errors when trying to measure a .112-40 threaded hole....

I am using a 2mm probe scanning helix 3 revolutions, 500 points  and a speed of .02 ....is that not slow enough?

 

Thanks in advance for any help .....

 

 

 

 

[[Ze...]]

Have you tried a smaller probe diameter like a 1mm? 

[[Ni...]]

Try using Cylinder Form Lines (upward scanning lines) with the largest probe that will fit in the bore, this acts as a mechanical filter.  At a slow speed with Outer Tangential evaluation.  With an XXT you will likely always get air scanning errors, regardless of the speed, sensor just can't handle large deviations during scans.  If its going to repeat itself due to air scanning I would just crank that speed up and accept the error and extra program time.   

[[Je...]]

1 - For XXT - Go to "Compatibility Settings" and disable "Scanning Optimization for Passive Sensors" to turn the repeat pass off.  This is a general advisement.

2 - Helical scan should work just fine, make sure the pitch you are applying to the helix matches the thread pitch.  Do 540-720° at 20% depth and at 80% depth.  Use only for evaluating location.  Not size.  Try to use a stylus that will "fit" in a thread without contacting thread shank for best results.

3 - 3 or more linear scans (bottom of hole to top) at very slow speed, evaluate as max inscribe (outer tangential).  This will give you minor diameter but be very careful of your filtering.  Since you are only using the peak of the scans, filtering will have a significant effect on your reported size.

For shorter threaded holes, I advise locking the vector of the axis.