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Old 2016-07-19, 10:57 PM   #6
Justin LE
Mad Scientist Type?
 
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Join Date: May 2010
Location: Vancouver
Age: 37
Posts: 120
Quote:
Originally Posted by tholub View Post
Beautiful! But will the nylon gears be up to the challenge?
Yeah, they should be up to that. All the ebike hub motors use nylon gears like this and generate similar peak torque levels to what a rider puts on the cranks (~60-100 Nm), and they usually only have 3 planet gears. Here with the load spread over 5 planets I think there's a really good margin of safety. The main concern would be if any foreign debris got inside the motor which could wreck havoc on the nylon teeth.

It's interesting that we don't see any plastic gears in IGH bicycle hubs even though they are ubiquitous in motorized hubs. I think that's a result of keeping the target diameter small which means much higher forces for the same torque transmission.

Anyways yesterday I finished machining the main axle which holds the motor stator as well as the sun gear. One side has a 42mm diameter ridge to fit in the ball bearing cap on the frame and provide non rotating reference, and inside this is a 22mm x 32mm bearing for the ISIS spindle to turn in.
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And here we are drilling the holes for where the sun gear will attach.
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I also got around to installing the planet gears with press-fit ball bearings which should stay put on the small shaft without the need for a lockring.
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So now all the key mechanical parts are finished! But before it goes together for a first spin there is a bit of electrical wiring work to do first...
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Last edited by Justin LE; 2016-07-19 at 11:01 PM.
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