Jetpik JP-50 motor pump gear

47-Tooth Replacement Face Gear / Eccentric Cam Gear

This is a replacement gear I reverse-engineered from a broken plastic part using measurements taken with a digital caliper and several reference photos.

The original part is a 47-tooth face/crown-style gear with an eccentric upper cam feature, central shaft hole, grease channels, annular groove, and a recessed bottom.

The model was developed iteratively with the help of ChatGPT by OpenAI. I provided photos, measurements, and test-fit feedback, while ChatGPT helped reconstruct the geometry and generate the CAD/STL models. Several revisions were made after comparing rendered models with the original part and testing actual prints.

The final printed version works successfully in the original mechanism.

Main dimensions

47 teeth

Outer diameter: approx. 24.6 mm

Central shoulder: Ø17.2 mm

Eccentric upper feature: Ø11.1 mm

Central boss: Ø5.8 mm

Bottom recess: Ø13.5 mm × 2.5 mm deep

Overall height: approx. 11.3 mm

The shaft hole may need slight adjustment depending on your printer, material, and dimensional accuracy. On my print I corrected the nominal hole diameter to compensate for printing tolerances.

I also found that trying to reproduce the rounded tooth crests caused poor results in plastic, so the final printable version uses a simpler tooth profile without the rounded tops. This printed much more cleanly and still meshes correctly in the mechanism.

Printing notes

This is a relatively small mechanical gear, so dimensional accuracy matters. Print with fine layers and good cooling. Before installing it permanently, check the shaft fit and tooth engagement by hand.

The geometry is based on measurements from one original part, so small variations may exist between different revisions of the mechanism.

Design process

Reverse engineered from the original component using photographs, caliper measurements, test prints, and iterative CAD reconstruction. CAD assistance and model generation were done collaboratively with ChatGPT / OpenAI.