Plastic welding. What's the drill?

[Ixion]

These days I seem to be accumulating quite a lot of broken, cracked and generally munted plastic bits . No, I've not broken them myself, I've gotten them like that.

Now, in the good old days, when all bike parts were made of decent honest cast iron, fixing broken bits was easy. You welded, or brazed them up. With the trusty oxy torch. Which I can still do tolerably well.

Unfortunately, (and IMHO very ill advisedly) manufacturers seem determined to use more and more plastic and less and less cast iron nowadays.

Which leaves the question, what does one do when it gets broken ?

I know that broken plastic CAN be welded up. But I doubt that it involves an oxy torch.

I see plastic welding kits on Tardme for around 500 - 600 bucks.

But I have no idea of whether they are any good or not (it's rather a lot to pay for an experiment). And where do you get filler rods (I presume some sort of filler is required). And such like questions.

And ,and , and , generally.

Anyone know the gubbins on it.

Oh, and is it hard to do? And are the results worth it, or does it just look like crap anyway, and it would be just as well to stick with fibreglass repair kits and Araldite?

[Subike]

Plastic welding. What's the drill?

Its that thing that makes holes in everything you point it at.

Plastic welding? Only some types of plastic can be welded, you are probably better off using the fiberglass as you discribe for most repairs.

[madboy]

When my green 636 went black I got a couple cracks fixed up. Crazefox did the whole job. Might be worth having a yarn to him.

[hayd3n]

a cheap welder will be sufficent for little jobs easy with a bit of practice you can buy all the welding rod look on guards etc for product code

[hayd3n]

most fairings abs most huggers etc polyprop

[MIZXR]

Soldering iron, some spare fairings or even some form of plastic, melt the two together with a bead at the back and fairing repaired and in a lot of cases better than the crud "professional job". easy

careful not to burn the plastic or something ..forget tooo drunkkkk

[MIZXR]

Crome too hard to weld witha soldering iron, much better with plastic
yet too make a larger hole too.

[hayd3n]

Plastic welding. What's the drill?

Its that thing that makes holes in everything you point it at.

Plastic welding? Only some types of plastic can be welded, you are probably better off using the fiberglass as you discribe for most repairs.

almost all plastic fairings can be welded as long as they are actually plastic.
i should know i am a plastics fabricator, andi try to fix ppls bikes when required , fibreglass will only bond to some plastics (it will bond to abs/pvc/styrene etc) ,for small abs repairs (cracks) i make my own glue, i use abs (can use scrap as long as its clean) and mek( methyl ethyol ketone) eventually it will break down the polymer chains and become a liquid this will form a very good paintable glue , with a brush!! also you can just use the mek in small cracks just brush on the inside of the fairing and eventually it will soak in about 3-5 minutes ,and will form a permanent bond in 12-24 hrs but totaly ridable in a hr


i can do a video of the welding this week if you would like and you will see its quite simple with a bit of practice

[hayd3n]

Soldering iron, some spare fairings or even some form of plastic, melt the two together with a bead at the back and fairing repaired and in a lot of cases better than the crud "professional job". easy

careful not to burn the plastic or something ..forget tooo drunkkkk

you have to determine which plastic it is first! a soldering iron will not allow the new (welding rod) to penetrate properly and will do a temporary fix so when you do your respray it looks all pretty for about 6 months then one day your riding along and it falls off lol
all surface most be clean form dirt and paint the welding rod will not bond to it if you dont

[erik]

I've just used a soldering iron (40W I think) and made a flathead screwdriver shaped tip with one corner rounded, to make it easier to mash the plastic together and smooth it etc. We had some ABS at work that I used as filler.
There's some photos of what I've done here:
http://s38.photobucket.com/albums/e118/edorp/sv650s/

When I was looking for info on it, I found this 'how to' which is basically what I did:
http://www.sportbikes.net/forums/how...stic-weld.html

I had a bit of a problem with painting it, I think the lacquer reacted with the plastic or one of the previous coats. it's not too noticeable though, so I haven't fixed it yet.

[hayd3n]

Crome too hard to weld witha soldering iron, much better with plastic
yet too make a larger hole too.

whats this large hole your talking about i just vee out the crack/break if needed, you can drill a small hole at the end of the crack to stop it goin any further tho!!!!!!!!!

[Blackbird]

Hi Les,

This is an extract from my mate's website in the UK. I know it works because I've seen a photo of the repair he did to the front of his Blackbird after a pheasant hit it!

Cheers,

Geoff

You have two options here. Either send it to somebody who specialises in repairing bodywork, or do it yourself. It is surprisingly straightforward to weld plastic panels, although it does take a modicum of skill and practice - so start in an area that isn't obvious, if at all possible, or practice on unwanted bits that you may have around the shed. For cracks that are clean, undamaged and undistorted, you can actually achieve invisible mends, good enough not to require re-spraying. However, anything less than perfect mating edges will mean that there'll be a visible scar. Be careful around mounting lugs, and anywhere that's intended to take strain, pressure or tension. Repairs at these points need to be as strong as possible, but without altering the dimensions of the effected parts. It's no good having an invisible repair that perfectly mates two previously separated parts of a fairing if the headlight can no longer be re-mounted!

This option is an excellent one for short-term remedial action that'll put you on until a replacement part is found, as you're not as concerned about the final finish. You can even add-in alien sheets of plastic to fill-in for missing sections to achieve that necessary weather-proofing, and the like. Sheets of suitable plastic can often be found in those plastic boxes that you have around the place, the stuff the Autoglym product comes in, or the Muck-Off kit you have. But, beware, there are as many types of plastic as there are plastic objects ... almost. Some will mate perfectly happily, but many will reject each other by curling up at the opposite ends of the job from each other! Test it out first, and be sure that they will weld successfully well after they have cooled.

The welding technique is pretty straightforward. Start by getting hold of some plastic coat hangers - preferably black ones. The plastic that they use for almost all hangers is near identical to that used in the manufacture of fairing panels - convenient, eh? You'll need a soldering iron with a large bit, something about 5mm across its flat end - don't use a pointed one. Get the iron nicely hot, and up to working temperature. If you have a variable iron, then set it to a moderate heat - this is better than very hot as you reduce the risk of burning the plastic.

Bring the two edges of the panel into close contact. If the split or crack doesn't hold itself, then temporarily secure them together as best as you can. Keep checking the finished side of the work to judge alignment and fit. Gentle pressure bringing the two pieces together during the cooling process works well, but don't overdo it and end up distorting the job!

With the pieces in close contact, and working from the non-finished, or inner side, place the iron a mm or so to one side of the join, with the flat of the bit facing it. Feed some of the plastic coat hanger into the point of the iron, where you're holding it against the panel plastic. Use a small blob of the hanger plastic, severing it from the hanger using the iron tip. Apply gentle pressure until both the plastics soften, and as they does so guide the iron tip slightly down into the panel plastic and towards the join. Pass through the join and hold the tip on the opposite side until you're happy that the opposite side of the join's plastic is also softened, and has merged with the blob that you have now transported across the weld area. You are, in effect, pushing bow-waves of melted hanger & panel plastic from one side of the split to the other. Do this slowly, and with due care that you don't dig too deep into the plastic and end up going through! Although you're pushing plastic across the join, on each pass try to leave some at the join itself for optimum strength.

Repeat this process as though you were sewing the two sides of the join together, working alternately one way and then the other. Take your time, but try to be fluid and smooth. Get a feel for how malleable and viscous the melted plastic is, and hence how fast you need to work to ensure that you don't tear strands away, or leave the bit too long in one place and risk going through.

[hayd3n]

I've just used a soldering iron (40W I think) and made a flathead screwdriver shaped tip with one corner rounded, to make it easier to mash the plastic together and smooth it etc. We had some ABS at work that I used as filler.
There's some photos of what I've done here:
http://s38.photobucket.com/albums/e118/edorp/sv650s/

When I was looking for info on it, I found this 'how to' which is basically what I did:
http://www.sportbikes.net/forums/how...stic-weld.html

I had a bit of a problem with painting it, I think the lacquer reacted with the plastic or one of the previous coats. it's not too noticeable though, so I haven't fixed it yet.

those assumable professional plastic welds didint hold as it was welded to paint not actual plastic

[Dan Mapp]

I have a hot air plastic welder and I'm b***ed if I can get it to work proper it just makes a mess. But every so offen i have another go so must get the hang of it soon.

[erik]

those assumable professional plastic welds didint hold as it was welded to paint not actual plastic

They had made a small v in the back of the crack, so it was welded to the plastic, but it seemed like they didn't get the fairing hot enough to actually melt with the weld bead. They must have been trying to limit the heat so as not to damage the paint on the outside.