New round of units going out, these include some changes I've been working on over the winter.
Old on top, new on the bottom. The 6806 bearings are a bit small, so in with 16005 ZZ C3, oh yea. These are twice the strength, C3 clearance for high speed and temps. They're a touch wider so I had to re-do the other pieces. These gears are 7075 Aluminum running against a steel ring gear. Steel for the eccentric gears is overkill, thousands of miles and they look brand new. Shown here is the eccentric assembly with steel gears blued from hardening.
I'm going to produce the 40:1 ratio for all the kits. This ratio is a great starting point as we can easily achieve overall ratios to the crankset of 44:1 all the way to 95:1 using commonly available freewheels and chainrings. This updated design fits all existing gearboxes. If someone has an issue with their 6806 bearings, they'll get the new design.
By reducing the turn count of the Astro motors by 1, we can shift more work to the gearbox and generate less heat in the motor, by quite a bit. A 4turn 3220 has winding resistance of 0.032ohm while a 3turn is 0.019ohm, almost half. The previous 3220's were 4turn and overall 40:1 ratio; the 3turn will run at 55:1 overall to produce identical performance figures, but for longer because of less heat. Same goes for the 3kW kit, instead of a 7turn at 55:1, we'll use a 6turn at 75:1. Another upside is 12s packs work great. 14s is bonus now.
Aluminum gears are 40% the weight of steel but as strong as a mild steel. New gear profile has quieted things down and 10% more output pins increases efficiency and robustness.
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Oh, new spring loaded tensioners too.
-dave