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  • 3D Printed Spur Gears?

    Has anyone had success with using 3D printed spur gears? If so, what material did you use? I have printed a couple in PLA but have yet to try them in any kind of car. I am thinking if I do, it will be a very low RPM / power type car. I have some Delrin spur gears that I obtained years ago and have run out of them. Just wondering if anyone has had success with 3D printed ones.

    Peter
    PetesLightKits

  • #2
    Hi Pete,
    I have printed a few but haven't used them in cars. PLA tends to shrink a bit and the axle holes end up too tight. And it's a pretty narrow band between too tight to get on the axle and too loose. I have broken and warped a couple, just messing around. I have been playing with D shaped holes and grinding flats on axles to see if I can get it to work.

    Also, I have not invested adequate time to learn about coding the various teeth/pitch in customizers to get various ratios. Lots of work to be done.

    Theoretically, you could print in ABS or even PETG that would be much stronger than PLA. Again.....areas that I haven't explored yet, but hearing from others would be interesting.
    Come Race at The Trace!
    Timberline Trace International Raceway - SW of Mpls, MN

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    • #3
      Chappy,
      I have thought I would need to print with ABS. I don't have any at the moment and haven't printed with it at all. I may just order a small amount to see what I could do. I have used the gear generator in TinkerCAD and it seems to give a usable gear, but, if I recall correctly, I was printing with a 0.4mm nozzle and would definitely switch to a 0.1mm nozzle when I get serious. I think you could tweak the I.D. to get to a point where the gear would press on and then you could secure it with a drop of thick CA glue. Or generate a good press fit I.D. and include a hub and use a 2mm grub screw to secure it in place. I would think that would work with a low RPM motor.

      Thanks for the feedback. I think I'll go check out some ABS filament.

      Peter
      Last edited by PetesLightKits; January 19, 2020, 11:19 AM.
      PetesLightKits

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      • #4
        Hi Peter,
        Be advised that ABS shrinks differently than PLA. Do a little reading....apparently it also stinks. I haven't used it but you may want an all metal hot end.
        You certainly can tweak ID.....I just haven't had luck with the hub threads being able to hold a grub screw (yes, I have undersized the hole and let the screw cut it's own threads).

        CA generally doesn't have good shear strength...which is why gluing wheels on without roughing up the axle doesn't work. So that's what led me to the D shaped hole.
        Hopefully you will have more success.....
        Come Race at The Trace!
        Timberline Trace International Raceway - SW of Mpls, MN

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        • #5
          You'll need to crank up the heat with the ABS. I'm using the 3mm filament in my printer and have cranked the temp up to 245 degrees C with the bed temp around 95-110 degrees C. With my first printer, a solidoodle, it used the 1.75 filament. The most temp I could get out of it was 210 degrees C and that wasn't hot enough to get a very good print on a chassis. With the higher temps, I was able to make wheels for my track cleaner, 49 Chevy Cabover, and those wheels have been holding up quite well to the track cleaning chores.

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          • #6
            I have been experimenting for a while :


            The main issue is to make ABS stick on the bed.Used lots of hair spray.Material temp 245 bed temp 115.

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            • #7
              I have had a number of printed parts made for me -- all in PLA as far as I know. I have had trouble with set screws losing their grip. Apparently the plastic creeps/relaxes over time, so the force holding the set screw against the axle goes away, and the part starts to slip.

              I have just purchased my own printer -- an Ender 3 Pro -- so I will have plenty of opportunity to experiment. Simply using larger set screws may help. Or using different materials.

              Another solution might be a composite gear -- an aluminum hub on an otherwise plastic gear. Very much like many traditional commercial gears. It would not be a simple thing to fabricate.

              A brass sleeve over a plastic hub might work. You could cut the sleeve out of brass tubing. The brass would stand up to stresses long term. And press-fitting a metal sleeve over a plastic hub shouldn't be too hard. If the sleeve was thick enough it could be the threaded part, with the plastic being essentially a spacer.

              Ed Bianchi

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              • #8
                I don't know if I would bet my life on an all plastic gear holding on a plain axle. I imagine that set screws would be very easy to strip if you were using those. It would help to grind a flat on the axle in the appropriate spot so you would not have to tighten the set screw very much.

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                • #9
                  Hi Peter, ABS is the plastic that Scalextic uses for their chassis and bodies. Acetone is the solvent, mix some ABS plastic with acetone and let it sit for a while to make “ABS juice” put a thin layer of it with a putty knife on the bed. The ABS and acetone are stinky, the area should be vented. I haven’t tried hair spray yet and bed temperature that high, Thanks Alexis. I have run a .2 mm nozzle with good results, but haven’t found a .1 mm. One nice thing you can do with ABS is fuming, where the Acetone fumes smooth the surface.

                  Hope this helps, Paul



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                  • #10
                    UPDATE

                    I ordered some PETG because I have read that it is strong "like" ABS but without some of the inhernet printing problems. Will give it a go with some mild to moderate motored cars.

                    Peter
                    PetesLightKits

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