The other day, I had to run a program that a predecessor had written that checked the location of threaded holes. What they had done was to drop a probe into the center of the threaded hole, touch off N,S,E,&W, then raise the probe to a second level and do the same, creating the cylinder.
I instantly wrote a new program. Number one, there's no way to get an accurate hole location off threads in that manner. Instead, I'll either scan the cylinder, using the appropriate pitch to match the thread, or thread a plug gage insert into the hole and scan the male shaft that extends above the hole. (I know there are gage sets that accomplish the same thing, but with the tolerances I'm generally looking at, my methods should suffice). Number two is "the demon". I've read in multiple places about measuring a cylinder with two planes of 4 touches each, and why it's frowned upon, as the consequences can be strange. I just wasn't too good at explaining to my boss why this is something to avoid, and why I didn't use an established program.
Can one of you gurus lay it down in words they'll understand?
I'm on a Global Performance 12.15.10, using PC-DMIS 2018 R2.
