Machinists: What's the best way to re-thread a bolt and the hole it goes into?

Question

I have a rolling chair with casters that screw into the base, but one has stripped out. Both the male (bolt) and female (hole) threads arer stripped. I can't find a similar caster, so I want to rethread this one. I know how to use tap and die to cut threads, but are there any tricks to make the re-threading work well in this case?

I ended up using epoxy and that did the trick.

Answer 1

You'll probably need a threading die to get the male's threads re-set. But maybe you can get a re-nu threading insert to get the hole into the proper shape. Call a distributor like J & L Industial Supply to see if they have the right size for you. They shouldn't be too expensive (neither will a die if you're willing to go import), and you should be able to get tech support to assist if you're unsure.

Answer 2

It won't work if you've stripped the threads inside the hole. To cut deep enough threads to grip again, you'll need to make the threads on the caster larger, but they're already stripped and you can only cut them smaller at this point. You may be able to find some type of thread insert you can screw into the hole and then screw the castor into the insert. One place I've seen them is at auto part stores, but not sure these would work for your application.

Answer 3

How To Rethread A Bolt

Answer 4

One type of female thread insert is called "helicoil". It is available from any auto store.

Answer 5

I ended up using epoxy and that did the trick.

Answer 6

cutting oil if it doesn't work, well try epoxy