Plastic welding - Update!!! pics added

[cb1rocket]

Hello all

so plastic welding.............basically what am I doing wrong?

I have welded a car bumper bracket once using a soldering iron but without using any filler or the like as it was quite a thick so there was enough plastic to mould into the break.

Any how I thought i would just post up some pictures of the panels that i'm trying to repair with tiny success. One of the panel tabs has totally broken off so i attempted to weld it back on.

See pic

Its not great as again I have use no filler or the like. I did try to use some cut up plastic from a gravy lid or a milk bottle lid but it just didn't stick, am I using something that isn't a suitable plastic to use as filler? Or is my welding technique totall wrong?

I'm using a 100 watt soldering gun and as such melting the plastic in direct contact with the iron tip. Wrong or what?

What should i be doing/using?

Cheers

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[alun111]

You need to use a similar (or identical) type of plastic as your "filler".
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[timR6]

You need to use compatible plastics,
Assuming the part your trying to repair is ABS, then in an ideal world you would use a piece of ABS as the 'filler' - something like a cable/zip tie works well in my limited experience

[Ichy]

Plastic straws or, obviously, broken fairing parts work very well.

[cb1rocket]

thanks guys, will try my broken jigsaw cutter casing and see what happens.

Its plastic from 1979 for a GP100 so not even sure if ABS was around back then!

[Robby]

I needed to reattached some plastic tabs a while ago, and found that a decent epoxy was better than amateur plastic welding. I used the strongest one that Maplin do, cost about 7 quid and it'll last ages. Designed for use with plastics, too.
The epoxy is stronger than the surrounding plastics, and I smeared a fair bit over the surrounding panel to spread the load a bit.

[Teflon-Mike]

Looks like you have got the joint deep enough, but when you add the filler, yes it has to be a similar plastic, but also you need to broaden the 'pool' of molten plastic melting old into new to get a more homogeniouse mix over a wider area, other wise you just get a crack full of new plastic.
reminds me: must get that How to written up!
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[bacon]

[cb1rocket]

thanks mike!

Yeah its a first go at doing something fragile unlike the car bumper bracket i did 3/4 years ago.

Will try my broken jigsaw casing as filler at some point (haven't got round to it). Pretty sure its ABS as most things like casing and covers are the norm these days.

Will write up when I get something done about it.

[BumpingUglys]

[cb1rocket]

Hi all

After breaking my jigsaw cutter casing into bits, i got this far.

The pictures shows the extent of the repair so far.

So far its loooking pretty good and i must say the jigsaw casing is a good plastic (possibly ABS type) as a filler. Got it hot it enough that I managed to molten the plastic into a jam like spread.

Its feels much stronger as i tried to seperate it with some force without breaking it.

Cheers for all help guys

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[DrDonnyBrago]

If you run out of jugsaw casing, me and bacon used plastic coat hangers yesterday and it seemed to work well .

[Frost]

I used plastic welding on a bit of a bike before... it cracked open again as it was on a bit that flexed slightly when you sat on the bike. Fiberglass done in lots of thin layers using that tissue stuff rather than the weave is absolutely spot on i think. You can use if on the visible parts to as it fills very fine holes and can be sanded down. bloody strong stuff too if done right.

[Lynxx]

when ever you weld plastic make sure u use the same plastic type or it will hold for no time at all. also make sure u bond and fill the plastic together. also when ever you weld plastic it will hold, but makes the plastic brittle due to the heat. somtimes its better to just use some epoxy and fiberglass material. or fiberglass but fiberglass is heavy.

Also to add, if you can get some stainless mesh, weave that into the plastic as it improves strengh. i used stainless bug screen off a screen door.

[loply]

I found one of the best techniques for adding strength to plastic welds is to embed wire in the joint.

I would take a series of 15mm long bits of strandy-core electrical wire and fray both edges and lay them across the crack like stitches.

Then I would use a big soldering gun to melt the wire down into the plastic, then melt more plastic on top, till the wire disappears from view.

This seems to help massively with strength
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[kramdra]

ack!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!




STOP. This ^ is a nasty joint, it will crack. If it was a metal weld, that is what would be called pigeon shit :p


The joint broke for a reson. You need to make it thicker to reinforce it. And your reinfocement should flex to absorb any forces.

Epoxy would not allow any flex, might crack again. Also messy :O


Hot glue. Heat it with a lighter, smear in circles into and around the joint. This gives it strength, quickest, easiest....


After - heat up one end of a trimming blade and use that to spread the joint smooth... looks much better after.

Plastic welding is better done with the correct solvent, or atleast a temperature controlled soldering iron set at ~230...

[chris-red]

[BumpingUglys]

[gonzo]

ok can i just say this am new here but will give you some help on this get some old ABS fairing and get a drill and drill into the plastic and the small bits you get of the drill bit put in a cup with some 99.9% ACETONE (ch3.co.ch3) and put a bit of the acetone in to the cup and it will melt,mix it up and put some on the crack if you can put some holes in the bit thats broken so the stuff melts into the holes aswell for strenth, let it dry over ngt ,and trust me you will be happy the ngt day
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the gonz

[0ddball]

ABS plumbers cement can be useful too. Basically a ready mixed acetone/abs shaving paste.

[cb1rocket]

[stigger]

OK So I've a question... I've bust the corner off my screen, I don't care whether it see though or not I'll probably paint it anyway...

I've tried super glue and epoxy neither of them worked can this be "welded"? If so what sort of filler do you think will work???

[gonzo]

--------------------------------------------------------------------------------

OK So I've a question... I've bust the corner off my screen, I don't care whether it see though or not I'll probably paint it anyway...

I've tried super glue and epoxy neither of them worked can this be "welded"? If so what sort of filler do you think will work???
use just as if it was a bike fairing b/filler on the inside and like paint it matt black thay look cool like that
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the gonz

[Noxious89123]

Not sure what screens are made of? ABS or some might be polycarbonate?
ABS plastic melts in acetone (nailvarnish remover) iirc, and can be used as a sort of cement. Just a thought, be don't ask me for more details as I don't have any Might be worth having a google for it though.

EDIT:
Nvm, had a look and found this. https://forums.clubrsx.com/showthread.php?t=558435
If you could get some clear ABS plastic you could use that to make some "ABS goop". But this is all depending on the screen being made from ABS and not Poly carbonate or something else.
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[DrDonnyBrago]

I would be surprised if a screen was made of ABS. There should be a recycling mark on the screen somewhere, find it and look it up online to see what it means.