Sport Bikes banner

Status
Not open for further replies.
1 - 3 of 3 Posts

·
Site Sponsor
Joined
·
1,639 Posts
Discussion Starter #1
How to Plastic Weld

After a few people have asked for some "How-To's" on different subjects, I have finally gotten caught up after our move and will start getting these done.

*DISCLAIMER* I'm not very good at waiting for pics to be taken, nor am I very good at showing how to do things on video.. some steps I'll jump forward or backward on. I'll explain it in the text, but you'll just have to deal with the fact that sometimes I go faster than the camera. Also.. these are NOT the ONLY way to do the things I show. There are many ways to achieve the same thing, some may be 'better', but I've found that the way I do it works for me, and has been consistently of good quality for my customers. The way I do it is NOT the only way to do it.


I'll show you how to repair a crack using an easy-to-find (and use) Radio Shack Soldering Iron (Cat No 64-2802B). I sometimes use a "plastic welder", and sometimes I use Plastex, but typically, on a straight break like the one in these photos on an R1 tail, I just use a soldering iron and melt the two sides back together then reinforce from the back with a light coat of reinforced epoxy.

Here is the peice we'll be working on. It's an R1 tail that I had sitting around for spare plastic. It's gotten some irreplaceable tabs missing, and is only good for chopping up. It just so happened to have a nice, 7" long crack up one side.




Here is the crack. It's along the bottom edge of the tail, right under the 'shoulder' where the tail turns in towards the seat. It's a common place for a break, and kind of a pain for bodywork, because of the roundness of the area. Has to be done by hand...




This is the implement of destruction: A Radio Shack soldering iron. Part number 64-2802B. It'll cost you about $15 (I think) at Radio Shack. It comes with a normal pencil-tip. It's relatively easy to use, easy to find and does a pretty good job even for someone with no experience. The downside: It's going to look bad.. but not worse than a busted up fairing. You CAN do the welding from the backside if your'e careful not to go through and mar up the paint. You'll end up with an 'invisible weld' that will last until you can get the bodywork and paint done correctly on the surface.



The sandpaper. On the left is 180 grit. On the right is 80 grit. I buy the 'DA' pads instead of the square peices of wet-n-dry because the pads can be folded in half and 'stick' together instead of folding a peice of paper in half and have it slide around.





First off, I clean the area up using some degreaser. Just to get anything that might end up in the plastic (grease, wax, road-grime) and contaminate it. I dont know if it'd actually hurt the weld, but it just makes for a cleaner workplace if the peices are cleaned off. Plus, I'm planning on repainting this, it'll have to be free of waxes anyways, so why not do it now..


 

·
Site Sponsor
Joined
·
1,639 Posts
Discussion Starter #2
I've sanded both sides of the break with the 80 grit. This gets ride of any shards of paint that are sticking up, and scars up the edge of the plastic a little bit.



Here I've sanded the area with the 180 just to prepare the area for putty after the plastic welding is done. Ideally, you shouldn't need putty, but the soldering iron makes some pretty deep grooves fast, so a thin coat of polyester really helps smoothe it back out after you're done. The 180 grit scratches really give the putty something to bite into. Always thinking about down the road....



This shows that the two sides will go back together flush and that there are no gaps that will need to be filled. If there was anything keeping it from mating flush, it would need to be taken care of either with a peice of 80 grit sandpaper or a dremel.


Here I've tacked the break. By 'tacking' it, I've just welded one small dot at the end of the break so that the break will stay together while I weld the rest of the break fully. Sometimes the 'tack' is just deep enough to hold the peices together, then I come back later and 'deep-set' it. Other times I 'deep-set' the tack at the start. Depends on the stability of the break.

Here is a short (horrible) video of me tacking the peices together.
http://www.grasshoppercustompaint.com/misc/HowTo/PlasticWeld/vid1.avi

 

·
Site Sponsor
Joined
·
1,639 Posts
Discussion Starter #3
Then I start at any spot and start welding. I start a weld by pushing the tip of the soldering iron at an angle down into the crack, forcing two 'levees' of plastic up on either side of a groove cut by the iron. I then push the levees of liquid plastic back into the goove while the plastic at the bottom of the groove is still liquid hot also. When it dries, it's a solid weld of plastic without adding any more material.

http://www.grasshoppercustompaint.com/misc/HowTo/PlasticWeld/vid2.avi







After a bit of cleanup work with the soldering iron. this is what it looks like prior to any bodywork. Not pretty, but strong enough to flex over 2" front to back. More stress than any 'normal' use will put on it.




After a bit of sanding with the 80 grit to get rid of some highspots the soldering iron left.. it's all ready for bodywork now.

 
1 - 3 of 3 Posts
Status
Not open for further replies.
Top