# What is the tolerance on gear pitch?

I'm trying to make a gear to mesh with a motor shaft that I bought online, but it doesn't give any information about the pitch or diameter. When I measured the diameter and pitch of the motor shaft, it doesn't seem to conform to anything metric or imperial. So I just guesstimated how big the teeth should be and how spaced apart they should be and designed a gear from scratch. I 3D printed some test gears to see how they mesh, fine tuned it, then printed a full size gear. The teeth appear to mesh very well, but its very very loud, which I am predicting is due to the two gear pitches being different.

After a bit of research, I figured using a gear generator would be much more accurate. I generated the gear based off of the circular pitch (tooth size). Now I've narrowed the correct tooth size down to 3.2mm $$\pm$$ 0.2mm. But I don't know if this will work any smoother than my original. I don't want to waste a huge 12+ hour print on a gear that wont mesh well. What kind of tolerances do I need for proper meshing? Will 3D printing even provide enough resolution for a quiet and smooth fit? I am using an Ultimaker 2 by the way. I appreciate any insight I can get.

• Are you even sure its a involute gear? can you give number of teeth and inner/outer diameter. It might just have a profile shift. Anyway there is no info to solve your problem – joojaa Feb 6 '19 at 6:15
• A motor shaft tends to be cylindrical possibly with a flat, do you mean a worm gear? A picture would help, with dimensions. – Solar Mike Feb 6 '19 at 9:14