Thread: tech query

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Tonight on the job I opted to weld in a hole, drill and re-thread a hole ( M4) rather than drill oversize. 1/8" plate. The threads felt a little rough when complete. I was wondering if I should have drilled oversize before I welded, would I have gotten better thread

I have been using nutserts which work much better than trying to thread a thinner piece of metal.
Unless the weld is perfectly smooth, tapping into it will produce a lot of porosity and a weak thread.

I'd say your fill metal is much harder than the rolled plate material. Your threads are cutting away most of the weld, leaving peaks of harder material trying to keep their bond to the softer base, and you're breaking off peaks. I've never had really good luck threading welded spots, and would probably look at cutting out a bigger piece and welding in a plug if it's something I needed good threads on, or use a nutsert...

there is a product by locktite for stuff like that

Originally Posted by jerry clayton

there is a product by locktite for stuff like that

You had me scratching my head on this one, Jerry, but that stuff is totally cool! Good for up to 128 ftlbs torque, and no hassles!! I'll be picking up a package just to have in the tool box. Thanks for the lead - Loctite® Form-A- Thread® Stripped Thread Repair - Henkel

In the application, a larger fastener would irritate the operator. As they would now need an additional tool at their workstation, and a nutsert wasn't an option due to parts fittment issues.

However, the locktite product just might have been the ticket.

Next time I have to weld in and re drill, I'll go oversize first. In the meantime, I'll try to get some locktite thread repair ordered.

on blocks and heads if i weld i open up the hole like a funnel with a bur bit but most all the time i like to use a insert that fitment is not a eschew with them as they can be set in flush. they called Timeserts there by far i feel the best inserts out there. i used and tried all of them. most car companys recommed Timeserts to fix bad threads . you did not say what metal it was if steel not to big of a deal to weld up but aluminum were if you weld you loose your heat treat like say T6 so if like a 3000 grade you end up with a weak fix but on a 4m hole that may not come in to play. when you get past m10 to 3/8 you better watch how you fix it . i have had not a class fit but still had a good thead pitch were the root of the thread s where still there were i used JB weld had good luck or 620 locktie with primer . not shure i would trust a cold epoxy fix it on a threaded hole that was strip out .any time you use a thread locker you want the sealer / thread locker on the non load bearing pitch of the thread or bad things can happen. so you run the fastener up to torque when sealer /locker is still wet .if part needs to come off many times the 620 or jb weld is not things to used less you do not care about making any new friends ...short of a nuke blast or very hi heat its not going any were