Segmented Change Gear - Proof of Concept Test

This project arose out a discussion with the owner of a liquid resin type 3D printer, and his inability to print change gears as they were too large for his print bed. I do not own a liquid resin printer, so I tested my design with my FDM printer, but I think the concept should work generally.

There is still an open question as to whether resin printed parts will be strong enough, and if anyone with a resin printer would care to test that with this print I would be interested to hear about it.

For this test I used a 65 tooth gear, but the CAD files are parametric so other tooth counts should be relatively easy to create. The gear is divided into six overlapping segments which are interned to be glued together. The segments have hexagonal registration pins and holes to aid in aligning the parts for gluing. Each segment also has printed in “registration dots” to make sure the parts are assembled in the correct order. Note that while each of the six segments look very similar, they are all slightly different so it is critical to assemble the parts in the proper order and orientation.

Edit Apr. 26, 2021 : Added STL files for a 63 tooth gear. I have not test-printed these files.

The OnShape 3D CAD files for this are here:

https://cad.onshape.com/documents/8b1dd73c76f98dbc0b6e470b/w/8cebe04f324c8fdae3668986/e/9448875566495c1053930a46

Print Instructions:

Print in PLA using the 3mf files provided. The segments print in sets of three, one set each for the “top” and “bottom” sides of the gear.

Before gluing the segments together, I made sure to de-burr matching edges. I also lightly sanded the mating faces with 100 grit sandpaper.