My plastic repairs.

[alchemysa]

(I mentioned in another thread I would post some details about this.)

When I got this bike both mudguards were snapped in half, one of the side panels was in three pieces, the front plate had a big chunk missing, and there were numerous other cracks around the place.

The tools are basic and cheap. You just need a soldering iron, a hot glue gun and a good blade.

1. Trim off any rough edges that might prevent the pieces fitting tightly together.

2. On the underside of the crack use the soldering iron to weld the pieces back together. Tack it at the ends first, then the middle, then work right along the join. I like to work the plastic into reasonably fat little 'bridges' across the crack.

3. Use the soldering iron to make an extra 'keyline' on each side of the join. This will give the hot glue a wider area to bond with the plastic.

4. Smother the weld with plenty of hot glue. If necessary you can tidy the glue up with the soldering iron. (You can also use this method to reinforce any weak spots you think might be prone to cracking in the future)

5. If you stop at this point you'll have a pretty strong repair and the crack on the exposed side will be almost invisible. However I like to seal the joint by running the soldering iron along the front. This aint pretty but it adds a bit of strength and prevents grit and dust from getting into the crack. If you really want to get serious you can sand the whole joint smooth then paint it. (Rattle cans do a pretty good job).

6. For repairs that require greater strength you can use the soldering iron and glue on the front and back of the join. I did that on the mudguards as they were snapped completely in half, and the repairs were largely hidden under the seat and the steering head.

Normally you will be joining two identical pieces of plastic so they will weld together quite easily. However my front plate presented a further challenge because half of it was completely missing. To patch it up I used a piece of plastic from an old black wastepaper bin. Using a stanley knife I cut a piece to the desired shape then used the soldering iron to weld them together. The weld wasn't perfect because the 2 types of plastic were slighly different but it was good enough to hold together and give a good key for the hot glue. I also used a piece of the bin to make a small holder for the key and neutral light that I fitted behind the front plate. Not pretty but it works and could be painted up one day.

I'm no expert at this. A pro repairer would probably be horrified but it works for me.

Cheers.

[alchemysa]

More pics..

[alchemysa]

Front plate repair

[Weldangrind]

Thanks for the detailed write-up. I now use a plastic welding iron, which has a wider shoe for greater contact area. As well, I purchased filler rods in PVC, ABS and PP, so I can have similar plastic if needed. I find that Krylon Fusion is excellent on plastic parts, once repairs have been completed.