Based on the FRC 125 design found here.
Using a design from FRC team 125 as a base, we have developed a reliable 3D-printable 2″ mecanum wheel with 1/2″ hex bore.
Changes were done in OnShape by Tyler Bletsch, the model is available here.
Download the STL files, STEP file, and a Google Doc version of this write-up here.
Key changes from the FRC 125 design:
- Unibody hub: Print as one piece with supports instead of two+screw/glue.
- Axle change: Added slots for wire bending: Roller axles are 18AWG (~1.2mm) steel wire bent at either end into the slots provided. Large paper clips and picture hanging wire seem to work. Old design used dowel pins with no apparent means of securing them.
- Letter stamps: The wheel body pieces are labeled “R” (right) and “L” (left). There are also “A” and “B” labels to indicate top and bottom, but these are irrelevant.
- Chamfered hex opening.
- 3D prints:
- 1x unibody hub (LEFT or RIGHT)
- 5x rollers
- 18AWG (~1.2mm) steel wire: may be picture hanging wire, jumbo paper clips, etc. Copper wire could also work, but it would be softer.
- Optional: 3 in 1 oil (like this)
- Drill with 1/16” bit
- Needle-nose pliers
- Wire cutter
- Print what you need. For wheel hubs, turn supports on and print on a face.
- Using drill, ream out the holes on the five rollers.
- (Optional) Put a drop or two of 3-in-1 oil on the face of the roller so it goes down the hole.
- Prepare your wire — you’ll need about 10” total per wheel. Run the wire through one side of the wheel, through the roller, then through the other side of the wheel.
- With a needlenose, bend the end of the into the channel on the wheel.
- Cut the other end of the wire so that the remaining bit can fold into the channel on the other side. Fold the wire as such. You may need to tap it down into the channel using a small hammer or hammer-like object (like the needlenose itself). Ensure the roller freely spins.
- Continue with the other rollers.