measuring threaded holes

[[Ri...]]

I have a few parts that we run that have internal threaded holes in them, and the customer calls out a true position of .1mm to datums A,B, and C. What is the best method of inspection to scan the holes with the threads in them to get an accurate positional measurement? Right now, I have it programmed as a cylinder and use a helix scanning motion. Is the best method, or is there another way?

[[Ri...]]

thread help-2.PNG

[[Ma...]]

Depending on how course the thread is I like using linear scans dragging up the threads not pushing. I use a pretty high step width and for the outliers use a 1.00 / 3.00 factor or inverse so it eliminates the pitch and and only takes the minor / major diameter on a 3 iteration. Lastly use a decent sized probe for mechanical filtering , spline filter, LSQ.

I would also stay away from measuring your threads using max inscribed evaluation. Out of your 5153 points you are only really collecting enough points for calypso to create the smallest cylinder possible from the data. Its a very unstable and not repeatable evaluation if you are trying to find a location of a thread. Max Inscribed is more of a functional check evaluation.

[[Se...]]

Hello guys,

If you are looking for an easy and acurate way to evaluate TP of threaded holes, you should try with Coordinate plug gauges.
We are using them for years and never had any problems till now 😉

Coordinate plug gauge.jpg