I can't really advocate against using glass fibre enough for plastics repair. It's really an expensive, long winded, messy temporary fix that will fail down the line. That's not to directly "piss on your chips" Big Mac, although I am sure it sounds like it....
The thing with resin based fixes is that the resin doesn't stick to plastic so you need to rough it up to get it to mechanically grip it but this only needs a knock to loosen whole portions of the resin from plastic. Some things you can get away with this (and I have used it in the past) but it will eventually fail so your at the mercy of luck more than anything. Oil covers etc are not too bad but anything that flexes, fairings, mudguards etc are prone to failure. I have spent time getting a really nice finish and its lasted a week, I have slapped some on a part to make do for a week or so and its ended up outlasting the bike! Also you need to finish the presentation side of the piece anyway, presumably with a filler, this is again prone to fail. With plastic welding your fix is on both sides, requires no foreign filler and has no risk of failing.
I have used the hot air + plastic sticks that came out and they are good but expensive ( well they were ), I presume this is what Deefer uses. I did do some experimenting with a soldering iron, using an old fairing to cut slivers of ABS plastic to use as the filler/welding rod. That gives a really good bond and finish, is quick and the fix is almost as good as standard strength wise, your not using a filler that has different properties to crack/come unstuck etc. A lot of people say use tie wraps or coat hangers but they are not good to use, the plastic is different and when you heat it enough to properly melt into the fairing ABS it becomes brittle, you can actually see this when you fix the part, if you flex it you see the different plastics as they flex differently, or not at all. I think this is what prompts the use of paper clips and suchlike to strengthen the join, this is not required in my experience. Use ABS from a fairing, ask a breakers or whatever for some bits they are throwing, it really is the best stuff. I guess you could buy the rods used in the proper kits but I remember these being a bit thick.
You can't beat the proper kits and I am sure that Deefer can fix one in a jiffy with his, I remember using mine and it was a doddle, like icing a cake almost. The solder iron is a bit more fiddly but for a first timer it is probably easier because things happen slower and you don't need to dremel out a groove. The final results are more or less the same.
So as a quick cheap repair all you need to buy is a temperature controlled solder iron, I got mine a while back from CPC for £25. No messing with smelly resin and glass fibre, no waiting for things to cure and its easy to sand. The cheap "stick" ones are a bit crap because they heat to one temp, hot enough to solder with and really its a bit hot but you could give it a whirl, they are about £5
Without further ado... I fixed my fairing tonight. I am planning on respraying it so needed to fix the thing first. Took a couple of hours from start, removing the fairing etc, clearing a space in the garage, seeing to my daughter, sanding and then putting some undercoat on - to finish.
So this is the fairing on the bike. The crack is clearly visible, I am not entirely sure how it broke, I bought it from a breaker for about £30 or so IIRC. The crack has dostorted the plastic slightly so it will need sanding flat before welding. I find sanding flat first is easier as you can line them up and know its bang on when you need to sand down the welded part later, you also know that once you sand the weld smooth your done, no need to check for steps or whatever.
Here its starting to get flat enough to weld.
Ok this picture (below) has the first pass at welding done, you can see the black scar. I have given it a light sand to see any low spots. High spots are fine at this point but any low ones need a bit of a tweak with the iron+rod. You will probably need to do 2 or 3 sand + checks to get it perfect. Remember this will provide the final surface so your not going to have to put any filler etc on so you might as well take the time to get it right.
Here I have blown some undercoat on just to do a final check. Sometimes it looks great and you get your paints out and wham, undercoat shows up some problem areas. This was bang on really. You can't see any issues here. "My god man you painted a dirty fairing", yeah I know... This will be getting a wash, sand + respray tomorrow so I wasn't too bothered about this tonight.
So all in it took about an hour start to finish. I did it just in the garage, no nasty smells etc. The solder method doesn't produce nasty smells unless your burning the plastic, I use temps from 150 to 220 C depending on how its going. The cost is just £25 for an iron and that will pretty much do as many panels as you want, zero cost if you already own one.
Topic: Plastics Repair (Read 11009 times)
