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Old Nov 30, 2012, 01:59 PM
fotoflyer is offline
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United States, TX, Richardson
Joined Oct 2011
307 Posts
I have bent a few prop shafts on my Super Cub from nose-in landings. So I bought several replacements - you have to buy the whole assembly. Here's my problem. In EVERY new assembly I bought, the plastic gear on the prop shaft is NOT centered on the shaft. In other words the hole in the plastic gear was NOT drilled in the exact center of the gear. So as the gear turns, the edge of the gear, where the teeth are, moves in and out. This is called "runout".

When I install one of these shafts with gear in my gearbox, and run it, first it makes a lot of noise, second, you can see the teeth of the plastic gear going in and out of mesh with the pinion gear on the motor. Some of these gears were so bad that they actually stopped rotating because the mesh got so tight.

I recently bought two assemblies from my LHS, and they were both bad. Then I bought two from HH and they were bad also. I have called HH and they basically say - that's the way it is - that I'm the first one that has complained. Well, yes, you COULD fly with this situation, it's very noisy and makes the whole plane vibrate (this is the same plane with the 808 #16 camera on it, so I don't like all this vibration).

Bottom line, have any of YOU had this runout problem or am I just too particular. I'm not a mechanical engineer, I'm and electrical engineer but either way I would not feel good if that was my design and my production tolerance. I would make sure the hole was drilled in the center of the plastic gear. How hard could that be anyway?

OK, I'm off my box. Thanks for any comments.
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Last edited by fotoflyer; Nov 30, 2012 at 02:01 PM. Reason: typo
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