by model murdering » Tue Aug 20, 2019 3:48 pm
Hi Scott,
I reached into the box of many gears and took samplings.
T-jet idlers .396" - .400"
AW idlers .403" - .406"
T-jet driven .396" - .400"
AW driven .399" - .404"
... so there's some range within the brands, but not a lot. I dont know of any substitutes of slightly larger diameter. As for the plastic idler running on a brass driven gear, I wouldnt worry about it. They've been running on brass armature pinions since day one. I've run the possible combinations with no ill effect, OR particularly remarkable improvement ... :lol:
What I'm always looking for is to avoid combinations of plastic gears that will produce a disharmonic buzz or "thrumming" clatter at a particular point(s) in the RPM range.
Bill