Make Your Own Plastic Friction Welder

[Fran] shows us how to build a plastic friction welder. It’s a method of connecting plastic pieces. While it’s new to us, apparently this type of tool was given to kids about forty years ago to use with craft project (when plastic was all the craze).

The tip of the friction welder is a styrene rod. If it’s spun fast enough the friction will cause the material to heat to the melting point, depositing a bead of styrene into the joint. The tool seen here is a cheap DC rotary tool acquired from Harbor Freight. It really did a horrible job, but [Fran] discovered that it was the power supply that was under-rated. When she replace the wire that feeds it and used her bench supply it spit out 16,000 rpm without any trouble. The welding rods can be found at the craft store and fit the chuck of the tool quite nicely. You can see her demo in the video after the break. The seam she’s working on comes out very strong, surviving a slew of violent whacks on the workbench.

We’ve seen a few other methods of welding plastic. One used a tool much like a soldering iron, the other depends on ultrasonic waves and clamping pressure.


63 thoughts on “Make Your Own Plastic Friction Welder

  1. Interesting – if somewhat obvious (i.e. welds are stronger then glue joints).

    But Fran, please learn to edit, you have 2 minutes worth of info dribbled out in a 13:41 minute video.

    With video, It’s all about the pacing.

    1. In that friction welding, plastic “glue” are essentially the some process, softening the plastic so the material from the pieces being joined can flow together I was somewhat surprised at the results. I’m guessing that friction welding can make up for sloppy preparation that could make a bad glue joint, and that welding ads extra material in a fillet that glue doesn’t.

      In the event Fran is reading these comments. Don’t worry about the editing, just put your time into making videos with interesting content. This video has no more superflerous material than those by the engineering guy( who buy the way probably has a paid staff writing a script directing editing his videos) the videos made by the Hackaday staff et. al. Challenge skippy here to edit the video down to two minutes and not create a dry video.

  2. Harbor Freight also sells a real plastic welder for cheap, but it needs a compressed air supply (boo!). Then it occurred to me, without even trying it, I’d bet the farm that my $100 Circuit Specialties hot air rework tool will work as a Jim Dandy plastic welder! Of course, you will need a rod (It is best to use a rod of the plastic you are welding). Be sure to work the “triangle”. Orient the hot air stream so that each of the parts being welded get one third of the heat, and the rod gets one third. It’s legal to tool a nice weld fillet before everything solidifies, using a bit of appropriate diameter wood dowel with a rounded end.

    1. jimbob, had you considered maybe skipping ahead or speeding it up if it wasn’t good enough for you? Use your buttons.

      And Fran, ignore jimbob! Your videos are MUCH better than most rambling vloggers.

  3. Great info, I’ll have to give it a try with my dremel and maybe build up one just like you did with the Harborfreight special. Some people don’t mind non edited videos…you can always skip around…better to get it up than to spend a bunch of time editing…It’s content not necessarily quality that people want.


  4. I have the same little rotary tool. Think I will rewire it and attach an external switch.
    I am quite impressed with the video. I’m wondering if I can put this to work repairing broken parts on my R/C monster truck.

  5. I accidentally did some friction welding of ABS the other day, I was cutting some discs out of old printer shells with a holesaw to put together into pulleys and thought I’d be smart and cut out several at once, of course once the first disc was cut it spun with the holesaw and the friction against the next layer caused the two to weld themselves together.

    Kinda like this, except in plastic, on my drill press.

  6. Fran and her lab must be pretty far out if she tables she refers to by their number. Not sure what age group these where targeted to in the the early ’70s I don’t recall seeing these at all In the event it wasn’t in the Sears Christmas wishbook it would have been unknown. At that time this small town didn’t have a variety store anymore, and the hardware store didn’t have much of a Christmas or toy sections yet. A fast spinning motor with a hollow shat would allow longer welding rod to be use, taking less time to change out short rods.

    There is this for sale;
    And this too;

    1. I thought they were cool, but Mom thought the Saws and stuff better. Granted, the only things they would cut was Styrofoam, Balsa Wood and Flesh. Not deep, but enough to get your attention.

  7. When I was young, I had a “Power Spark Welder” which was basically the same thing as this, except there was a ring of sandpaper toward the tip that scraped flint when spinning, producing crazy sparks inside of an orange plastic cover on the front of the tool. The welds were actually very strong if done correctly, and it was tons of fun. Here is one I found online:

  8. So basically this works with many plastics, but you need a thin rod of the material first.
    I wish I could think of some way to get those easy and cheap, but my mind goes blank for the moment.

    Anyway it’s a good tip.

  9. Finally. A decent use for those unusable bits of filament I have left over. There is only so much abs glue you can make with it :)

    I tried it with 1.75mm filament. Works great, you need to swap it out quite regularly though!

  10. The best HDPE welding rod I’ve found so far is the tear away ring that comes on 5 gallon paint and drywall mud buckets. My grandparents have some ocean kayaks they use on a river and the bottoms get torn to shreds. A soldering iron style welder and a few strips of lid tear away strip and we were back in business.

  11. if you told me 10 years ago that you would one day see women on the computer stick weld plastic togeather i would have said nuts to you! (and cried because i was 11)
    XP but seriously nice job there! never thought of this! … nice use for my old dremel X3

  12. I wonder if you’d get better (deeper) penetration of the plastic by pushing the spinning rod rather than pulling it along the weld line.

    I just tried this with a smooth metal rod in the Dremel but it just creates loose balls of melted plastic without joining. I suspect that because the metal never really heats up, it’s just acting like a grinder and chewing out the plastic instead of getting it really hot.

    1. Nah it’s nto just the heat, I’ve cut in plastic where the edges melted, but when you don’t add material it just cuts.

      Otherwise you could also just use a soldering iron, but you’d only poke holes if you tried.

  13. I had one of those toys as a kid. I don’t remember many of the details, but there were “welding rods” that were white and rivets that were black. Can’t for the life of me remember what I was putting together (it was almost 40 years ago). I had this gun thing that simply had a DC toy motor in it. The rivets and rods slipped onto the shaft. Sometimes, they’d spin on the shaft (before any melting happened) and were useless.

    1. entirely different concept. in friction welding you are melting the edges of the pieces to be joined and adding extra material in the form of the melting welding rod. makes for a much stronger bond than hot glue

  14. They still make them for kids here in the uk, Gr8 kit scrapheap welder.
    Runs on D batteries and is basicly a prefitted chuck, a DC motor and a momentary push switch designed to take thier propiatry rods.

  15. I enjoyed the video mostly because of Fran’s genuine amazement at her own success. That said, while you are at Harbor Freight why not buy the plastic welder kit for $14 and use the long welding rods they sell too? You wont be stopping every 1.5″ and have better melted welds.

  16. Nice hack. I, also, thought it would rapidly come apart under stress, which just goes to show how wrong you can be. Mind you, these days, I never mind finding that for years I’ve had it all wrong: instead I think of it as a golden opportunity to move forward.
    BUT, has anyone tried this with Perspex ( maybe Americans have a different term ) It’s poly-methyl methacrylate and doesn’t melt: it only softens then burns. Glue joints are very strong for this material and possibly welding would not be an advantage.


  17. Fran, Thank you so much! I had one when I was a young boy, It came with a scale military boat. I have been looking for a tool like this for ever! Thank you for showing how to build one and most of all for the name of the sticks! I did not know they were made of styrene. Now I can finally weld plastic again. Greetings from Mexico city :D

  18. Don’t Laugh.
    Since I was Electrocuted in ’78, I don’t trust AC and high Voltage DC. I don’t trust ANYONE that says “Power Is OFF”.
    To this day, I get Zapped by everything. From the Woodwork in my house to the Shelves in a Grocery Store. It doesn’t matter what time of year, what the Weather is, what I’m standing or sitting on. To the point of wearing the most uncomfortable Rubber Soled Shoes. They didn’t help. The electricity comes right out of the Cement Floor, bypassing the soles and burned Both Feet. No one around me was getting Zapped but, they thought it was hilarious. They all got NEW Nicknames they weren’t happy about.
    I had to start wearing my White Cotton Socks with the Toe Seam over the top of my Toes because, the Little toes on both feet were so badly burned and blistered, the Seam would irritate them.
    When I get Zapped, I don’t care who’s around because, it just… Irks(?) me to no end.
    I’ve come up with some Extremely Colorful Metaphors and combinations of said Metaphors.
    Last Year, I was in my Kitchen and was just adjusting my pants. The Zap was so loud, bright, and, hot, it burned my FAVORITE Finger.
    The one used for Conveying Displeasure to some Meat-Sack that did something OVERLY Unwise, justifying said Finger’s main purpose.
    I do own a Dremel Model 595 Type 5, 5000 to 30,000 RPM Moto-Tool.
    What setting would be the right speed to do this Welding? There are 5 on mine.
    You can laugh now.

  19. You keep up the good work Fran. I wish my Workbench was as organized. I always wondered why Spin Welding Styrene or any other Plastic didn’t advance, especially in the Scale Model World.
    I’ve got some Evergreen 3/64″ 1.2mm. Styrene, a whole lot of spare Chucks for my Dremel, and plenty of Plastruct 1/8 3.2mm. Styrene Tube to act as a Spacer if I need it. I’m going to have at it with my Dremel.
    What’s the worse that can happen?
    As long as I don’t get Zapped hard, I won’t wet myself.

  20. Okay, using my Dremel 595 Type 5 on Setting 1 (5000 RPM) It worked. Setting 2 (RPM unknown), It Worked Faster.
    Setting 4 (RPM unknown), It worked even faster. Setting 5 (30,000? RPM), Holy crap on a Bicycle! It made a much better looking Bead and waaaaaaaaaaaaaaaaaaaaaaaaaaaay faster.
    This technique should look good on well worn Construction Models, Junkers, P.A.Vs, Trains, Ships, and etc..
    Thanks Fran and everyone else that contributed to this article.

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