KoP TB Mini- Transmission Seizing

[BoilerMentor]

Originally Posted by silverD

These are all great suggestions. Not to hijack the thread, but we too are having a similar issue where one of the TB mini gearboxes is louder and not as smooth spinning as the other. The really odd part is that it is worse when driven in one direction versus the other and seems to bind/catch. We've reassembled it many times, reversed the cims, and swapped out internals. We are beginning to wonder if the molded plastic housing is the problem. We are running a 13 tooth cim gear with 14 tooth center spacing.
Thanks for any help in advance.
Nate

That's .025" further spaced than they should be, per a standard gear spacing calculation. I would be extremely hesitant to operate a gear box like this, because you're most certainly outside the range of appropriate gear mesh. You'll see a lot of back lash between the gears, noise, and potentially irregular gear wear or even failure.

Center distance = (N1 + N2) /2P
N1: Number of teeth on Gear 1
N2: Number of teeth on Gear 2
P: Diametral pitch

Generally we add an extra .002" spacing to account for misalignment

(13+50)/2*20 = 1.575" --> 1.577"
(14+50)/2*20 = 1.600" --> 1.602"

In our custom gearboxes, even with the extra .002", we've had situations where we see binding on one side and free movement on the other.

for reference: http://www.engineersedge.com/gear_formula.htm