How do you repair worn out thread holes?

[Collin]

Hi Duderinos... one issue, all of us knows them (i guess), are woren out threads in plastic parts. There are various ways to fix them. Some work better, some does not work very well. Some work once, some work for long time. I want to know which is best solution for which situation.

My latest way to fix them is like this. I keep the round rods from the plastic trees, so I do have various material for inserts. Strong one from TR-15T/DS parts, usual black from standard models, ect...
Next, I drill out the used thread with a driller which is a few 1/10mm bigger than the plastic rod. Using 2k-Epoxy glue, some into the whole, some around the plastic-dowel and press it into the whole. After 12 hours I file down the overlap and drill the hole again.

 

Other solutions are tread lock, but which one? Some should not be used with plastic, as the melt it.
Some use Cyanoacrylat superglue, whis does work but not really easy to handle. I did it once with success and 6 times it was only mess.

Okay, spread your experience and knowledge!

 

[Peter_B]

I've used a bit of JB Weld in the past. Use a toothpick or similar to poke it into the screw hole.

Was recommended to me by @jonboy1

 

[Collin]

JB weld is 2k liquit metall, isnt it? I just know it from topping up material on transfere ports at 2stroke engines, mostly aluminum/alloy... You use it on plastic?!

[Juggular]

Your fix looks real good, Colin.  I've used Colin's method in wood before. Using chopstick splinters or toothpick, plug the hole and drill again. Didn't occur to me to use the same method on plastic.  If the sprue is the same type of plastic as the holes you are trying to fix, that'd be the best way.   

Somebody else recommended using plastic dust and superglue the same way Peter described. I suppose plastic dust can add volume.  

 

 

 

 

 

[StrokerBoy]

Not tried it for this, but I've had good results with Plastex for repairing 'plastic' motorbike panels and filling gaps.  Basically a solvent and some powder.

[taffer]

plastex is great for threads, fill hole with plastex, spray screw with wd40 (if i remember correctly) then screw in all the way, next day remove screw and new thread is left behind, i think its part of the promo material.....

[Collin]

16 hours ago, Juggular said:

Somebody else recommended using plastic dust and superglue the same way Peter described. I suppose plastic dust can add volume. 

This is usually done to prevent shrinking and its more or less what JB weld is. Some powder material mixed with epoxy glue. Shure its a bit more complex but thats the base.

14 hours ago, taffer said:

plastex is great for threads, fill hole with plastex, spray screw with wd40 (if i remember correctly) then screw in all the way, next day remove screw and new thread is left behind, i think its part of the promo material.....

Plastex sounds good! My method is working well but nothing I can do at home at my desk as a quick repair.

[Juls1]

I generally just put some tyre glue (cy/super glue) in the hole or even just on the screw and screw it back in the hole. Next time I back the screw out the glue stays in there and screw comes out clean. It only works really well for self tapper screws. For machine screws it still works but it’s not as successful every time. 

If the machine screws bring glue out with them I just clean the screw and glue it again.

[taffer]

check out

for plastex