In article
,
woodworker88 wrote:

The main problem is manifesting itself in that the low quality pinions
seem to be slightly over the correct pitch diameter, making proper
meshing difficult. Furthermore, the pitch diameter seems to vary
along their length, which makes it difficult to be consistent across
the 8 different gearbox parts.

First option - bite the bullet and order some good ones, even if it
means boring them out yourself.

Second - set up a sacrificial good gear and the 8 pinions in a dedicated
grinding setup, apply abrasive, and run for a while - but this requires
disassembly, reassembly, "cut and try" and building a new fixture, and
getting another good gear. If I understand grinding theory correctly, a
softer "good gear" material should embed the abrasive and grind the "bad
gears".

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