Custom Gearbox is very loud

[Billfred]

Originally Posted by Tottanka

We are using the 12 pinion once, and we did grease the whole thing.
The plates were made in our CNC machine, and the CAD was done according to pitch diameters of each gear. The loud noise seems to come from the gear that attaches to the CIM pinions (2 motors go to one VEX 72 teeth gear).
We would like to avoid fabricating the whole thing again, any suggestions? How much should we separate the gears beyond the tangent distances of the 2 gears?

Was it the exact pitch diameter sum, or did you add something to it? What is the actual center-to-center distance on the plate, as machined?

For drive in FRC applications (short runtime, friction bad), it's conventional wisdom to add about .003" to soak up manufacturing variations and go a little loose and free.