I would like to design a single stage planetary gearbox using standard gears.
There appears to be three primary conditions to ensure the geometry of the gears will fit - correct center distance, placement of planet gears around the sun, ensuring adjacent planet gears do not interfere.
A number of the conditions depend on whether the planet gears are evenly placed around the sun or unevenly placed around the sun. What does this actually mean? Using a ring gear of 100 teeth, three planet gears of 40 teeth, and a sun gear of 20 teeth - would the planet carrier physically position the planet gears 120 degrees apart, or would two planets be positioned 33 teeth apart and one 34 teeth apart, without causing interference of the ring, planet, or sun gears?
What is a good reference for planetary gear design?