Customizable Planetary Gearset (Cycloidical) by mechadense

Last crawled date: 3 years ago

caution: The code needs to be updated to use the new library:http://www.thingiverse.com/thing:777936
See instructions for some practical info.
A bit about some hidden logic in planetary gears:
Not every combination of tooth numbers allows to distribute the planets equally around the circumference. If the combination allows equal (equiangular) distribution it can be that the planets are a multiple of the minimal mounting distance away from one another (they are not maximally closely packed) making the assembly weaker than it could be.
To allow more tooth number combinations and have the planets as closely/tightly packed as possible the planets can be organised in groups (which is done here). For this the greatest common divisor of the gear teeth numbers defines the number of planet groups (starting points for filling). The number of sun and planet teeth is then defined by multiplicators to that common divisor.
The cycloidical shape of the teeth allows (and requires for small prints) toothnumbers smaller than in involute gears. The compatible tooth number combinations thus become more sparse. Groupling planets by the gcd value and distributing then in patches around the circumference allows more options.
Cycloidical profile pros and cons:
smaller toothnumber possible - more compact design possible
stronger for same pitch - less fragile teeth than involute profile
(-) pressure angle can't be adjusted
(+) it has less parameters than "normal" gears
(-) pressure angle is varying max-zero-max -> potential vibration -> more wear & friction
(+) wider contact area (concave on convex) -> less wear & friction
? more efficient than involute profile ?
(-) distance between axles is not continuously variable (irrelevent here)
(-) harder for subtractive manufacturing
smooth profile -> allows higher printing speeds
v2.0 228 dwnlds
v2.1 30 dwnlds (explosion view deactivated - timeout problem?)
v2.2 current (slight shifts for pretty preview removed - due to slicing problems)