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ALEXKYRIAK

Screws...when the plastic goes soft...?

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Hi all, during the current build, I have encountered a couple instances where the screw going in sort of goes a bit soft in the plastic once it's fully in. It feels like it's due to over-tightening. Am annoyed about this. What can I do, if anything, to fix it once it's happened?

I will play with the torque setting on my 12v power drill (as recommended by Nitomor on the 'tool fetish' thread), however up til now I was using the power drill to get the screw 95% of the way in, then finishing the last bit by hand. 

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I've had a similar issue due to putting the screw in too fast. The heat generated melts the plastic. I now use a Bosch IXO with torque adapter set on the lower setting I can get away with and if doing groups of screw tighten each one a bit at a time.

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If you inject or push in some 2 part adhesive like araldite into the hole then use a needle to make a small hole to tap into, leave to dry and the screw will take again.

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Plumbers tape can work well to give screws more bite again, it's thin white and very soft so mounds to the inside of the screw hole ever so gently filling it out again allowing the screw to bite down.

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If you have stripped the hole you can fix it by drilling it out to take a bit of scrap parts tree which you can glue in place, then when the glue is dry, drill a new hole of the correct size to take the screw.

I've done this on a few things and it has never failed me yet. 

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2 hours ago, ALEXKYRIAK said:

What can I do, if anything, to fix it once it's happened?

Take out screw, drip some superglue down sides of hole, let it dry & reinstall screw.

If it happens again with the same hole, cut a sliver off a toothpick/matchstick, glue that into the side of hole then screw in again.

Don't use powertools to tighten the final nudge, even the lowest torque setting is too much. Screws into plastic should be just snug, nothing more.

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I agree with you. For scrwewing into wood and metal, power tools are fine. For the tiny 3mm screws into plastic, I'm always doing them by hand.

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Try using a metric fastener. In my experience an M3 will fit snuggly most of the time and bite down better than a self tapping screw. Feel free to use a power tool, as in this case the heat generated will actually help re-shaping the thread.

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Thanks guys much appreciated for all your advice. Have been following the 'screws into plastic should just be snug...' mantra for the rest of the build and this has been pretty successful! Nice advice WillyChang. 

 

Will try the plumber's tape or araldite solution for the suspect screws I came across earlier. 

 

Cheers :)

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meh my patience doesn't last long enough to wait 5mins for epoxy to cure. Araldite don't adhere all that well to chassis plastics anyway, seems to peel off after a while.

Plumbers tape is Teflon, that too ain't that sticky <_< save that instead for brass balls whose ball cups have gotten sloppy. Stack on 2-3 layers, snap the cup over it then pull off excess. 

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I use plumbers tape more for its volume to fill the missing gaps for the screw threads to bite.... but I guess it needs to stick inside there as well.

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