Tearing Apart A Hot Glue Gun For A 3D Printer

If you’re building a 3D printer, the most complicated part is the extruder. This part uses a series of gears to pull plastic filament off of a spool, heats it up, and squirts it out in a manner precise enough to build objects one layer at a time. [Chris] made his own extruder out of a hot glue gun and made it so simple we’re surprised we haven’t seen this build before.

The basic operations of a plastic extruder – pushing a rod of plastic through a heated nozzle – already exists in a hot glue gun available for $3 at WalMart. To build his printer, [Chris] tor apart the hot glue gun and mounted the nozzle on a piece of plywood. The hot glue sticks are fed into the nozzle with the help of a 3D printed gear and a stepper motor driver.

After the break, you can see [Chris]’s hot glue gun RepRap printing a 10cm cube. It’s not fast, but the quality is exceptional, especially considering he made it out of a hot glue gun.


42 thoughts on “Tearing Apart A Hot Glue Gun For A 3D Printer

  1. I had this idea in my mind for so looong time, finally somebody build it!. The pros are:

    1. Hot glue is cheap
    2. Easy to find everywhere
    3. Hot glue guns are cheap to and easy to modify
    4. Used pieces can be recycled easily

    Is not the perfect alternative for every kind of piece, but the relation benefit/cost is huge!

      1. I don’t think ABS is possible. There is no temperature control for one thing. According to WikiPedia the HiTemp hot glue gun is around 193C and the Low temp hot glue gun is around 121C. ABS temperature for extrusion according to Reprap.org is around 220C. The HiTemp could probably do PLA which is around 185C. You would probably be wise to have some temperature controls so you can set the exact temperature as I think I have read that plastics are a bit more temperamental about their temperature. A bit colder and it doesn’t work. A bit hotter and you have a stinky poisonous mess.

        After all that PLA is worth a Try! Nothing beats just trying it. Start with a Hi Temp hot glue gun (still $3) and put some PLA filament into it. Probably want to do it outside.

    1. decreasing the extrusion size increases the pressure required, if he can still grip the hot glue then yes, it might even be possible to add a syringe like needle through the existing head, (cut short)

      I like the fact the resulting prints are going to be flexible. one could print a cellphone bumper or whatnot.

      hotglue comes in a variety of colors too, and there are some instructables on how to make your own.

    1. Even better: Jolly Ranchers.

      In reality though, I don’t think chocolate, or any kind of candy will work.

      Sugar is a very particular thing. Gotta get the temps and timing just right or it comes out anywhere from gooey to dry and brittle.

  2. I have been thinking about this too. I was thinking that although the resulting objects would not be very strong, they might be good candidates for a lost wax type process (lost glue?) and casting in Aluminum or resin or???, ending up with parts much stronger than direct printing with typical reprap materials.

    1. Strong yes. Rigid … not as rigid as ABS or PLA. The bigger the object the more rigid it is. The MakerBot Coin I printed is really thin and therefore quite floppy. It is strong though as it is tough to tear it apart. I am going to try harder hot glue at some point. I bought a bag but haven’t had time to try it.

  3. AFIAK, this is how the RepRap guys started out, by using hot glue. It’s a neat idea, but really how practical is this given that the size of the filament is so thick?

    1. The size of the filament determines next to nothing, the pressure at the -tip- and control of such as well as it’s diameter on output have final say in just about everything. Filament reversal was designed to counter these (chamber compression-ratio) problems. It is worth noting you can buy mini-glue sticks as well.

  4. Check out the Instructable:


    @proxc ->
    If you search around Instructables.com you will find how to make sugar glue sticks for making confectionary stuff. I wouldn’t run that through one that used glue sticks though… might taste weird :)

    Spring loading is a great idea! I was going to do that and was part of one of my cardboard prototypes. It is harder than just attaching the bearings and since all my glue sticks are 0.28″ in diameter it didn’t seem to be that important. Will file that for later though as I had forgotten about it.

  5. Also forgot to mention. The Hackaday article said the gear is 3D printed. I sourced the gear from a HP printer I had in my junk pile. It has around 100 teeth as was used to drive the paper feed I think. It is made out of nylon probably.

  6. I was curious why hasn’t anyone thought to use cake Decorating tips in Conjunction with the extruder.

    Just a thought, seeing as you can get VERY fine detail tips for cake decorating, plus they’re stainless steel, also they have weird tips that you could do interesting patterns with.

    1. also a variation to the “Sugar Glue Stick” is to use Isomalt, has a better workability than sugar. it can be remelted over and over, it can be colored very easily with food color.

      I’ve done several sculptures using sugar and isomalt…by far I’d take isomalt over Sugar.

      Melting temp of Isomalt is 165°C, no watching for crystallization or anything like that. Also you can just break or remelt any pieces that don’t work for you.

      Isomalt isn’t as hygroscopic as sugar. So another benefit.

      As long as you keep a desiccant in the container you keep the broken pieces in, you should be able to melt it for quite awhile.

        1. the taste is a subtle sweet. it’s the same stuff they use in cough drops. it’s edible but there’s really no point to it.

          I buy mine from http://www.pastryprofiles.com/

          I took a class from Stephane Treand, he’s MOF and just a RIDICULOUS artist. Watching him airbrush is amazing.

          the Classes I took were on Pastillage(gelatin/powdered sugar/vinegar), Isomalt, and chocolate.

  7. Another idea for larger objects it’s a kind of “inverse printing” or “hot glue sculpturing”: Put a big block of hot glue and using some sort of “hot vacuum needle” . Probably would be faster and better finished

      1. Might as well just put a block of plastic there and put the dremel tool / router back on the CNC platform. Neato idea though. That would make interesting art if you don’t vacuum up the glue. It would drip all over the place and look really cool.

  8. Very nice concept… However my personal experience with hotglue guns is not that good. They tend to clog and I think you need to select the appropriate kind of metal tip to use this type of machine accurately for a long period without heavy maintenance.

    Stuff is also kind of rubbery so not sure what you would use if for other than some toys perhaps.

    1. I have been using the same hot glue gun for building things for 15+ years. No clogs ever. This makes a good, inexpensive entry level extruder. Get your feet wet first then go for a swim if you like the water.

  9. with the help of a micro controller and a temp prob and a pwm thermal control is possible and for better precision make or find better nozzles for the glue gun it should be possible to make a decent extrudier for under $30 heck a whole 3d printer for under $100 and using glue sticks make it realy cheap about $1 per pound/Lb

    1. Probably don’t need the temp. probe or controller. Just better calibration. A smaller diameter nozzle would be good. The one on the glue gun I used is around 1.5 mm. Sometime when I get a round toit I am going to attempt to cut threads into one to screw on a cap screw drilled out for 0.5 mm or try to use some sort of solder to fill and redrill the hole.

  10. My company sells hot melt gluing systems. We had a customer who was doing something similar to this several years ago. While the machines are made for adhesives, they’ll deliver about any kind of material that melts up to approx. 450F. Applicator orifices can go all the way down to .006″ (typical use is .012″). They can also deliver up to 1500 PSI. The applicators are basically heated valves. This customer was using a special wax to make models and the $7K price tag for tank, heated hose, and applicator head didn’t faze them one bit. Of course, they were also using a $20K CNC machine to move the head around.

  11. “…we’re surprised we haven’t seen this build before.”

    “I had this idea in my mind for so looong time, finally somebody build it!”

    History is cruel. Long before Mr. Bowyer or RepRap (pre 1998) 3D printers were made by many tinkerers. Commonly they used this hotmelt glue method. They were typically called “Santa Claus Machines” for obvious reasons. Google it.

  12. Don’t quite see the point, it seems to me the usefulness of stuff made with this is limited.

    In fact I think using silicon-kit would actually beat it, although you’d need some sort of quick hardener, but I think those exist don’t they?

  13. Quite a nice tool. In fact I think you’ll get a higher pressure by grapping with 2 gears instead of one.
    Or you apply a tube to the intake, with a slit next to the gear, holding the hotglue. but instead of a plastik- you use a STEEL-gear, so even if the hotglue breaks it will be forst out of the tip.

    I hope for more. ;-)

  14. trying to build a similar system from an old standard 2d printer. Downside is it uses a combination of stepper motors and normal dc motors so have to have some sort of positioning feedback… plus side is im using a laser mouse for positioning… so could be quite accurate :)

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