Is there a "rule of thumb" for how far down a spring collet should be compressed before boring it to a desired size? 
I have a set of Snap-On metric stud removers that I use, but I want a collet in 12mm x 1.75mm and Snap-On doesn't offer that size. I just bought an old collet off of eBay and want to bore it out and re-thread it to my desired size. But I don't know how much to squeeze it down before boring it.
I have a set of Snap-On metric stud removers that I use, but I want a collet in 12mm x 1.75mm and Snap-On doesn't offer that size. I just bought an old collet off of eBay and want to bore it out and re-thread it to my desired size. But I don't know how much to squeeze it down before boring it.
Willie