Plastic welding

[TheJollyLogger]

Anyone else play around with this? I welded a cracked exhaust cover on my customer's echo brushcutter today, better than new strengthwise, but ugly. Does anyone have any good tips for finishing welds , maybe sanding/ polishing techniques so they aren't quite so rough? Jeff.

 

[Hddnis]

Add extra material and then sand with a belt sander, 320 grit and then finer if you want a polished look. Like anything it takes practice. Having a iron with adjustable heat output and a few different sizes and shapes of tips helps alot.



Mr. HE

 

[TheJollyLogger]

Cool, thanks for the tips.

 

[Big_Wood]

it is nice to have something that stays hot for plastic welding but when you get good you can get buy with just a torch and butter knife. when I first started plastic welding I used to use a wood burning iron for art but when that burned out I just started using the butter knife and torch technique. plastic welding takes one hell of a steady hand. if not you make a mess. you don't have to penetrate deep like metal welding. I cut a bevel in the plastic and it makes it much easier to make a strong weld throughout the whole crack or break or whatever you wanna call it. just melting the surfaces of a crack I find does the job but it isn't a like new fix. best advice I can give to make it look cleaner is clean it super good. like when you think it's clean, clean it again and use something like automotive brake cleaner. solvents like mineral spirits actually have residues that will discolor you weld. the cleaner it is the less discoloration you will get. once the weld is done I wet sand it, then polish it with never dull. I have done plastic welding lots but still can't get it perfect. i'm sure there are people that can though. also I use the frames that hold model parts together as filler when the color is close. otherwise I got on the hunt for something close. I've even used the orange caps of orange spray paint to plastic weld Husqvarna's :msp_thumbup: call me a skid but it works

 

[TheJollyLogger]

Actually I think the paint can lid is brilliant.

 

[Stihlofadeal64]

opcorn:


I've seen a few threads on the topic. But NEVER any before and after pics. (When you say "torch" are you speaking of a tig torch? One poster used a wood burning iron.). Standing by for answers.

 

[ja_cain]

I think he is using the torch to heat the butter knife then melting/shaping plastic with that. Plastic is usually non conductive so a tig torch would not work. I have done a lot of plastic welding and it takes a bit of practice to get it right sometimes. It can be tough to get fussion all the way through the crack if it is thick. You can buy plastic welding rods two in different materials and colors. Every time you take plastic above its melting point it degrades a little so it can be more prone to cracking. Hope this helps.

Justin

 

[cmarti]

I have not on chainsaws, but have a plastic welder used for ATV fenders. Dang trees keep jumping out in front of our rides:msp_mad:. 3m makes a peel and stick backing product for composite auto pieces, and it is tough and sticky as nails. You put the piece behind the weld to hold the seam and support it, then run your bead. I graduate sanding through finishing grit, and apply plastic paint.....however I have not made works of art....you can see the repair. It holds though. The auto pros can do a cover and you can't tell. I got a kit and rods a Harbour Freight for around $50.

 

[lumberjack48]

I did a little plastic welding, its almost like ark welding. I always tried to use the same plastic for fill in that i was fixing, worked the best. What i usually did, was clean it real good with sand paper and cleaner. Then tack weld it together, then use Epoxy on it, smooth it out, makes for a stronger then new repair job. I fixed a lot of saw gas tanks this way, all kinds of chainsaw repair jobs. When they fall off a pickup hood at -30, they break. NO, wasn't me, one of my crew had just bought a new 266, he set it on the hood of his pickup, showing it off. The pickup was running, having a quick cup of coffee before hitting the woods. There was just enough vibration, it slid off, busting the trigger handle off. He Epoxy-ed it back together, just as good as new.