Retapping stripped threads

About 9 months ago I attempted to relube my LXD500 mount and in the process stripped two of the screws that clamp on the worm gear for the RA. I used the expoxy-like thread repair kit to repair and it nearly worked, but with those fine threads and them being M3 and M4 sizes, it didn't really take and now I'm back to the beginning.

I was going to grab our tap & die set from work and went so far as to buy M4 and M5 machine screws to replace after retapping, but they look almost too big. Then I discovered our taps are not metric ...

So, is there something in the standard sizing just up from each of those that would be big enough to allow new threads to be cut, allow use of my existing taps, and give me a chance of success?

If it helps, the two I stripped: one is the small screw that holds one side of the worm-gear enclosure in place and the other is the center screw that allows you to back the gear off a little to lighten the resistance.

Any thoughts appreciated ...

>>So, is there something in the standard sizing just up from each of those that would be big enough to allow new threads to be cut, allow use of my existing taps, and give me a chance of success?

Did you mean allow use of existing holes? Existing screws?

Have you tried just re-tapping the existing holes, You may be able to rethread the stripped threads using your new taps?

Alex

Heli-Coils or King-Serts. Both will allow you to drill out the hole to a larger size and then install an insert which will bring it back to standard size.

Jon

Kevin
According to a Starrett chart a M3 screw takes a 2.5mm or (.984) drill so you could try a 6-32 screw which takes #36 drill (.1065). This is close so the stripped hole may be large enough already or could be a bit too big. If it is, than an 8-32 screw should work which takes a #29 drill (.136).
The M4 screw takes a 3.3mm drill (.1299) so a 10-32 screw would take a #21 drill (.159).
The move from M3 to M4 and the M4 to M5 would be a bit closer in sizes but if you don't have them then the 6-32 or 8-32 and the 10-32 are the closest standard sizes
Hope this helps
Buck