Here you go
Originally Posted by two stroke mick
What is "Picking up"?
The problem is usually worse in tapped holes in fabrications, as the threaded holes tend to be hand cut. Captive welded nuts are even worse. If you do get a bolt picking up, you are in for some pain, prevention is MUCH better than the cure. Copperslip is the usual answer, but even then I've had fastners pick up, no fun when it's an M20 bolt
Normally you would just cut it off & start again, in your case with a glassed in fab, you need to be careful.
When you come to start screwing fixings into the matrix, use lube, go slow & if it suddenly starts to get tight without bottoming out, leave it to cool & slowly unscrew it. Inspect the male thread & it will show signs of damage as if it's been put in cross threaded. Bin the male thread & run a 3rd tap into the hole to clean the female thread & start again.
Try to buy good quality fastners, not all stainless is born equal
There is a lot of unbranded imported stuff around & it's sh1te, we've found that "Tigges
" and "THE"
brands have fewer problems, but even they pick up.