who's good at plastic welding ?

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weeksy
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who's good at plastic welding ?

Post by weeksy »

And fancies a little job on the lads MTB ?

Image

Middle loop top bit has broken off.... I've bought a spare (well, a new one AND a spare... ) but would be good if someone can fix it nicely ?
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Re: who's good at plastic welding ?

Post by Mussels »

Is it a safety critical part or is as good as new not essential?

Not that I can do anything better than you with some solvent but it seems the obvious question.
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Re: who's good at plastic welding ?

Post by weeksy »

It's a guide, it'll hold pretty well even with the bit missing.

So really it's only as a "do you have xyz" when someone has crashed theirs, not for my lad.
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Re: who's good at plastic welding ?

Post by Mr Moofo »

weeksy wrote: Thu Sep 19, 2024 3:46 pm It's a guide, it'll hold pretty well even with the bit missing.

So really it's only as a "do you have xyz" when someone has crashed theirs, not for my lad.
JB Plastic weld works well
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Re: who's good at plastic welding ?

Post by DefTrap »

I've mashed broken plastic together with an old soldering iron and judicious use of staples/wire etc to give it a bit extra bite. Typically ends up not pretty but useable.

Normally a way stronger fix than just glue anyway
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Re: who's good at plastic welding ?

Post by Silly Car »

Screwdriver repaired a couple of bits for me on my Daytona 955i back in the day. He did a really good job as I recall.
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Re: who's good at plastic welding ?

Post by Skub »

I bet @Screwdriver could print one of those.
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weeksy
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Re: who's good at plastic welding ?

Post by weeksy »

Skub wrote: Fri Sep 20, 2024 7:29 pm I bet @Screwdriver could print one of those.
I've already bought 2.one is on the bike now, the other is a spare. This one would be a spare spare to give to someone else if they crash and break theirs. So to be honest it's not worth the hassle of printing it. If it could be repaired in 20 mins then great, if not, it's only £40
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Re: who's good at plastic welding ?

Post by Screwdriver »

Yes I can fix stuff like that. I made a "hot staple" thing that works great on bike plastics for example but most of the time, a good repair just depends on the correct determination of the actual plastic type.

Amazing how many people think plastic is just plastic so you see them trying to weld a nylon zip tie to an ABS fairing...

Anyhow, bung it in the post and I can fix it.
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Re: who's good at plastic welding ?

Post by Mr. Dazzle »

Screwdriver wrote: Fri Sep 20, 2024 9:50 pm YAmazing how many people think plastic is just plastic so you see them trying to weld a nylon zip tie to an ABS fairing...
We plastic weld (brand new) stuff together inside our motors quite a lot, we of course know exactly what kind of polymer it is.

It's a difficult process, I don't like it and I try my best to convince people to get rid of it :D
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Re: who's good at plastic welding ?

Post by Screwdriver »

Mr. Dazzle wrote: Sat Sep 21, 2024 8:43 am
Screwdriver wrote: Fri Sep 20, 2024 9:50 pm YAmazing how many people think plastic is just plastic so you see them trying to weld a nylon zip tie to an ABS fairing...
We plastic weld (brand new) stuff together inside our motors quite a lot, we of course know exactly what kind of polymer it is.

It's a difficult process, I don't like it and I try my best to convince people to get rid of it :D
Yeah, I hear that! Obviously the best idea is not to have to weld plastic, ideally you wouldn't break it either.

Back in the real world, it is possible to getaway with a repair but even under the most ideal circumstance it's never going to be as strong as a homogenous part or unbroken piece. Not without some sort of reinforcing which can add it's own issues if the part needs some flexibility.

For the record though, the biggest mistake I see people make is overheating the parent material. Plastic(s) have a very well defined melting temperature, once over that, you're gonna start burning it. This is especially true with random soldering iron tips. A burnt plastic might stick but it will be a very brittle join.

You are right though, it is a mugs game really.
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Re: who's good at plastic welding ?

Post by Mr. Dazzle »

The biggest reason it goes wrong for us it cause it's too hot or too cold :lol: And that's with proper closed loop control.

I think the only thing worse to weld is chocolate, fortunately that's seldom used in structural applications.