Thread: Plastic Welder - anyone used?

I have the Harbor Freight plastic welder, and it didn't work for me on polyethylene. The heat was very hard to control, because the temp is constant, and air flow is all you can change. It tended to blow the molten plastic around on me.

Instead of fighting the air welder, I went to Urethane Supply and bought the KC Welder Pro. It's been a terrific tool, and I recommend it. There's an explanation of how it's used to repair a kayak on the site here. I don't have a kayak, but it worked great on my polyethylene dash.

I just use that 2 part mixture stuff that you mix together and it becomes plastic. Smear that on whatever you want welded together, sand smooth and you're done. I helped a friend take the Ford symbol out of his grille one day with this, looks awesome now.

I've been using the same welder that turbocad mentions. It has different heat settings for all the different types of plastics, plus it comes with rods of various filler material including a "universal" type of material.

If you don't feel like dropping $160 try the one that rdholtz mentioned (~$60). If that's still too much, go get a cheap soldering iron. Hammer out the tip so it's more like a butter knife, maybe even make one side a bit more thin for cutting/scooping. That should work, just make sure to get all of the material (both sides plus filler) melted together. It's good for the surface layers but I've found its a good idea to use something additional for structural support in the back.

Originally Posted by stealinfool

. . . just make sure to get all of the material (both sides plus filler) melted together. It's good for the surface layers but I've found its a good idea to use something additional for structural support in the back.

Using the welder takes some practice to get welds that go all the way through. I've successfully welded polyethylene up to about 1/8" (3mm), but I made some pretty bad welds until I got it all figured out. Practice on scrap, which you can dig out of the recycle bin or get pretty cheaply from plastic fabricators. See this post (it talks about PE, not PP, but it's still useful info).

For reinforcement, the KC Welder Pro (and its lower-cost sibling, the KC Welder) come with stainless steel mesh that's a great strengthener. You push it down into the weld as you make it. Urethane Supply sells the mesh separately in a pack if you make your own welder.

Here are a couple of my posts as I learned to use the welder: #19 and #56.

One lesson I had to learn is to use less force with the iron, and just allow the heat to do the work. It doesn't take much pressure to make things happen just right. If I try to force things, cold plastic doesn't flow, so I end up pushing the whole part, and there goes the alignment. When I let the heat do the work, the part stays in place, the material moves nicely, everything stays aligned, and the weld gets good penetration.

And one other very important thing -- use lots of ventilation.

I have to plastic welders on is hot air and the other is airless.I find it's alot easier with the airless than the hot air.I haven't used it yet but there is a plastic welding rod out there that will stick to anything 1)fiberflex 2)stickall rod 3)heat activated epoxy
I have used fiberflex and it works pretty good. I still want to purchace the other 2 and try them
I also bought a soldering iron with a temp display on it and this works really well for cutting the v-goove.I usually work with thin plastic.I have found that I can weld almost anything in the house now!If you can't find stickall rod or the heat activated epoxy let me know because they are hard to find on the net, but they are not that pricy!

Digging up old threads to add just a bit of info, since I'm searching for one myself...

Plastic Welder comparison chart: link
Bonding Guide: link
General Plastic ID Guide: link

I'd tried the Self powered Air Welder from Harbor Freight on my Firebird bumper. On scrap pieces of same material anyway. The thing sucks on that because it melt it to like an oil and sprays it all over...no welding done. And the included rods didn't help either. I'd try airless but I've been working with epoxies and glues.