[sanddrag]

You may consider trying the Macro mode on your camera (it usually has an icon that looks like a flower).

Anyhow, we experienced a near identical failure with AndyMark 12 tooth pinions on a CIM motor, mating to an AndyMark 50 tooth gear. We run at +.003" between the theoretical pitch circles. The gearbox rotated freely when assembled, but when running, we noticed wear and steel dust almost immediately. After approximately two hours of running, the teeth were nearly completely gone. Before they wore completely down, they turned to sharp points. We showed several professors of Mechanical Engineering at a local university who were just as shocked and baffled as we were.

It appears the gear tooth profile may not be a true involute curve as it should be. The gear teeth appear to be sliding against one another, rather than more of a rolling contact motion. My best guess is that something is wrong in the gear forming/cutting process, since the application/design we are using these gears in is not different really from any year past, and we have never experienced this accelerated wear before. I'm guessing that the pressure angle is not 14.5 degrees, or the curve is not a true involute.

However, I have not looked at it in too much detail, and there may indeed be something wrong on our end. We plan to hardness test the gears eventually, and perhaps harden new ones.

EDIT: We are trying new gears with grease, per Paul's recommendation. We'll post here again after more testing.