A Practical Guide to FDM 3D Printing Gears

• Print all parts minimum 3 perimeters all sides top & bottom, with 15% infill. I recommend 0.3mm layer thickness maximum.
• plastic is cheap and your time isn’t. If the application is critical or just cumbersome to replace a broken gear on then you may as well print the gear mostly solid to avoid the chance of any non-wear related failure.
• Printed gears usually require a little post processing prior to use. Expect to have to bore holes to the right size & clean up teeth with a blade.

The most common failure modes of printed gears

• Tooth wear until slipping
• Tooth breakage.
• Connection to shaft failure.
• Hub or spoke breakage.

What is the best material?

Nylon > PLA > ABS > PETG

• The drawbacks of nylon are its propensity to absorb water and the difficulty of printing with it.
• PLA has high rigidity and superior wear properties over ABS which make it a better choice when application temperatures allow.
• ABS a better choice for applications involving temperatures above ~75C
• PETG is a ductile material but it is also softer, more flexible, and less scratch resistant than either ABS or PLA which makes it a worse choice for gears.