Can you increase threads strength? with glues

[sendkeys]

OK well. I have a part here, I wanted a 1inch tapped hole 16tpi un.
I was hoping for 75% but after well... being careless i have a 50-55% thread. 50% should work but can i increase the strength of a threads, with say epoxy, lock tight,teflon tape(i would think no one this one) ? or something made for this maybe?


I know it must do something but i mean does it really increase the strength more than just couple percent.

Also same question can but not with a thread but with say a 1/2inch pin with a loose fit but you were hoping for a tight fit.

both should never be removed.

[jans123]

Originally Posted by sendkeys OK well. I have a part here, I wanted a 1inch tapped hole 16tpi un. I was hoping for 75% but after well... being careless i have a 50-55% thread. 50% should work but can i increase the strength of a threads, with say epoxy, lock tight,teflon tape(i would think no one this one) ? or something made for this maybe? I know it must do something but i mean does it really increase the strength more than just couple percent. Also same question can but not with a thread but with say a 1/2inch pin with a loose fit but you were hoping for a tight fit. both should never be removed.

I don't want to make you dissapointed, but no. It's only the area (axial) of the metal in the joint that affects the strengt, no, that's not true eiter, if there is a slip you will also get an increased bending force on the thread. Thats means that the actual stress on the thread is higher than expected only by comparing the area (axial). I can't tell for sure, but lets say like this, if you have a 100% strength with a 75% thread, you might get perhaps only 50% with a 50% thread, not the expected 75% strength. (Don't expect 50%, I just wanted to illustrate that it gets lower. It could be worse) The glue (whatever type) probably wont affect the strength, only help you "lock" the thread.
If you want to gain strength look at helicoil, but then you will loose area on the bolt... Sorry no simple answer here. If it's critical and if it was me, I would make a new part.
About the same goes for the pin. Here glue (eg. epoxi) might keep it from rattle in case of vibration and that might make fatigue problems a little less.
If it's critical, for safety or damage, you must make the decisions you selves.

/jan
(Sorry about my English. I'm working on it)

[sendkeys]

I was hoping with a glue filling the gap it would help the tips from shearing because with a "glue filled" v it would have to shear down a line but and without it, it could "peel" the metal.

That was just the picture in my head but guess it's not really so

thank you

[Aksess]

There is hope for you I have used this in the past it is a 2 part epoxy 1st part is the liquid metal 2'nd part is a releasing agent. You fill your hole with the liquid metal apply the releasing agent on your bolt screw it in and let it setup unscrew the bolt and wala it is fixed. I cannot rember the name of the product it has been years ago.

[pieface]

Is there any possibility of opening the tapped hole up to a bigger size and heli-coiling?

[DareBee]

Helicoil is good but requires a special tap, drill, and insert tool.
If you have the material I would install a Keensert - uses standard tap & drill.
We also use keenserts for most of our tooling that will have high traffic holes.

[mxtras]

I agree 100% with DareBee - use a helicoil or Keensert - both would FIX your problem instead of covering it up.

The stuff Aksess might be refering too - MarineTex??? I know it was advertised to be as strong as cast iron, and it is some pretty tough stuff - I have used it, but not to repair threads. I used it as an emergency repair on a lower unit on an old outboard motor and it held up very well - and it was a 75HP outboard. I have heard that people repair main bearing bores on diesels with Marinetex but I have never, ever seen anyone use it for a critical application such as that. It is strong enough to hold a thread, but I think I would choose a different route.

I would recommend an insert to repair an undersized thread.

Scott