Improving 3D Printed Gears




Introduction: Improving 3D Printed Gears

Here is a quick method of improving 3D printed gears using hot melt inserts. I have always found the failure point of 3D printed gears to be the nut trap method of shaft clamping. The hub usually breaks when you are trying to apply enough force to secure the shaft with the set screw.


  • 5mm hot melt insert
  • 5mm bolt ~30mm
  • 3d printed gear with well for hot melt insert
  • Drill bit ~5mm
  • 5mm Reamer (optional)
  • 3mm tap
  • 2.5mm drill bit
  • Soldering iron

Step 1:

Step 2: Insert the Insert

Using the tip of your soldering iron, slowly heat up the insert and press the insert into the gear until it is flush. Be careful not to get the insert to hot.

Step 3: Keep the Insert Straight

Quickly before the hot melt insert cools, screw the 5mm bolt into the insert from the opposite side of the gear. This will help keep the insert concentric to the shaft.

Step 4: Make the Bore the Correct Size

Using the 5mm drill and optional 5mm reamer, drill through the gear from the back side to increase the bore to 5mm.

Step 5: Set Screw

Through the set screw hole drill through the insert with the 2.5mm bit.

Follow this with a 3mm tap for the set screw.

Step 6: Conclusion

This is quick and easy. It only takes a few tools and can be completed in about 2 minutes.

more of my stuff:



    • Creative Misuse Contest

      Creative Misuse Contest
    • Tiny Home Contest

      Tiny Home Contest
    • Metalworking Contest

      Metalworking Contest

    9 Discussions

    What type of gear is that with the teeth shaped the way they are? Does that design keep the gears aligned?

    1 reply

    They are called Herringbone gears. They have the advantage of transferring power smoothly because more than two teeth will be in mesh at any moment in time


    1 year ago

    I use these


    2 years ago

    Great! Where can I buy hot melt insert?

    3 replies

    Sparkfun and Adafruit used to sell these - not sure if they still do.

    You can also get them on eBay. Search for 'Knurled brass insert'

    Does the hot melt insert provide a very strong mounting point? I've been thinking about incorporating this into some of by 3D printing designs.

    Great idea. This makes me really wish that I had a 3D printer. I could make some really nice gear boxes.