how to fix bad anchor holes

[RB]

Got a situation where I have one sheet metal panel held to a frame by 1/4" bolts. Another panel has 3/8" bolts holding it to its frame.

Some of the threaded keeper holes are worn out. Either boogered threads or no threads.

What is the best fix for this problem?

Sounds like maybe I should drill the bad holes on out to next std larger size bolt and tap 'em out. Is this best?

If so, would someone please check their charts and see what size drill bit I need for:

1/4" tap

3/8" tap

1/2" tap

5/16" is machine screw vice bolt, is it not? If I'm wrong on that one, may as well send the drill bit size along for a 5/16" tap, too, please.

[John Grabowski]

Here is a link to a drill and tap chart:

are also tools and inserts that you can use to restore threads. Check Mcmaster-Carr and also automotive supply sites.

John Grabowski

[R&D]

Just drill them out unless you want to spend money. Usually your tap set includes the recommended bit size, but if you just pick a bit that is smaller than the outside diameter of the tap then there will be metal that the tap can cut threads in to. Use oil on the tap and turn it 1/4 turn in and half turn out and repeat and if the tap feels like it will break as you turn it, go for the next larger hole size. You could even use self taping metal screws. note: for an engine block or if the frame is solid metal I would check and make sure you are using the correct drill bit. Goodluck.