Repairing stripped screw holes in plastic?

[strap624]

I've taken my wraith tranny in and out so many times that last night I stripped one of the holes out. What is the recommended repair? Long ago I read in Rc car action to put some CA in the hole and then cover the screw lightly with silicone shock oil and screw it in and let it set. Is this valid?

 

[xirtic]

This is not directly the answer to your transmission, but the process is applicable to really anything with a deep 3mm machine screw and a little material. It may help in your situation.

http://www.rccrawler.com/forum/axial-xr10/293775-harleys-complete-xr10-guide-5.html#post3233765

 

[KBrog]

You can try one of the 3mm brass inserts from McMaster-Carr that many here are using in the XR10 axles.

 

[sweli]

Helicoils

Helicoils!

Mcmaster Carr sells them. Not worth the cost to repair a few holes. I fab a lot, so I bought the kit shown. Tool is needed to insert them.
McMaster-Carr
Grainger and MSC carry them also.

If only a few holes to fix, there are alternatives that do not need a tool.
Some use a slotted screw driver, others an allen wrench.
Many types at Grainger:
Threaded Inserts - Fasteners - Grainger Industrial Supply


Quick shadetree fix to try: (does not work on Delrin/Acetal)
Sand/file some plastic chips from a spare part or the tree that parts kit came on.
Spray the old screw from the hole with a dry lube, teflon or wax based and let dry.
Goop it up with some extra thick CA filler glue and sprinkle on the plastic chips.
Drive it back into the hole and let set.
With some effort screw should bust free from the CA before the CA comes loose from the plastic.

 

[crawlhog]

i stripped one in my scx10 tranny and just replaced it with a 3mm screw, so far so good:ror:

 

[Luke088]

Very good thread. This is a very important question, working on plastic parts...

I stripped the hole of the Transmission set case of my SCX10 Rubicon.
There is 4 holes, and I figured I could run on 3 solid and one loose, but I should fix it soon.
I could order the part AX80009, transmission set, but I feel lazy to disassemble all the transmission...

I am planning to either use:
Plastic repair epoxy putty stick. I would fill the hole the best I can, then I will use a toothpick to compact it and leave a small hole the size of the 3 mm selftapping screw. So this way the screw would tap the hole, and I think it should work fine.

or
use an epoxy glue to fill completely the hole. Once solid, drill a 2mm hole and put the 3mm screw.

What do you think of my idea to fix it?

See my Rig, Rubicon, on my flickr album
https://www.flickr.com/photos/luke088/sets/72157647677083011/
Thanks
Luke

 

[Luke088]

Hey, thanks to cameron20118, he says :
This stuff works for me, it binds to the existing plastic.

PlasticWeld | Plastic Repair Epoxy Putty

And it is exactly what I have in hands and was thinking to use! bought at Canadian Tire
KwickPlastik from J-B Weld, PlasticWeld

So I will try it and let everybody knows when it is done!

 

[WAM]

I've done this a couple times. Coat a round toothpick with 5-minute epoxy, wallow it around in the hole to build up a layer on the ID and then tap it. Brass inserts are much classier, but this is surprisingly strong. And fast. But I have a set of small metric taps.