Restoring 1/4"-36 internal threads

On an aluminum body, have some thread damage at start of the hole,
cross threading I believe someone said. I know this is an odd size,
what are my choices and how would I go about restoring the threads. It
needs to be the same size and TPI as original to match 3 others.
Reply to
J. McClendon
Loading thread data ...
search
formatting link
for 1/4-36 tap, they list 5 of them from $9-18 each.
Reply to
John Sullivan
[ ... ]
[ ... ]
Except for rebuilding the damaged (probably stripped by now) threads at the start.
If it were a more common thread, and if there was enough surrounding meat to allow it, I would suggest HeliCoils -- but I don't think that you'll find a HeliCoil in 1/4-36. (And that fine a pitch suggests that the aluminum might be rather thin, too.
If it is thin, and there is sufficient damage to the threads so they won't clean up with just the tap, I would suggest finding someone who could TIG weld some aluminum into the existing hole, then drill it out and tap it from scratch again.
Good Luck, DoN.
Reply to
DoN. Nichols
I've had success on a few occasions using a scribe with a 90 degree bend at the tip. Round the tip a little if it's pointed. I start at the bottom below the bad threads and run it backwards, and it'll often straighten things out enough to hide the cross threading and let you get a screw started properly. YMMV.
Reply to
B.B.
||On an aluminum body, have some thread damage at start of the hole, ||cross threading I believe someone said. I know this is an odd size, ||what are my choices and how would I go about restoring the threads. It ||needs to be the same size and TPI as original to match 3 others.
Set it up in a lathe with a sharp 60-degree boring bar in the hole, in good threads. Set geartrain for 32 tpi, advance out of the hole rotating chuck by hand. Texas Parts Guy
Reply to
Rex B
See if you can find a thread "forming" tap. I have had success with these on aluminum castings.
Reply to
John Normile

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.