I'm building a simple 20:1 gearbox prototype with 2 compound gears in a row connecting to a third small gear at the end. My goal is to multiply the rotational speed of the small gear. They are all engaged on a straight line. But for some reason they get stuck most of the time. I'm trying to figure out what the problem may be. I had to make the shafts part of the base of the gearbox (cause my printer doesn't print support material, and I wouldn't be able to print a gear on top of a shaft), so each gear has a hole and it spins freely around the shaft. I don't know if that is less efficient than the shaft being part of the gear. I'm not an engineer to know those kinds of details. I'm also wondering if all the gears being on a straight line, somehow causes them to lock in place most of the time. I was hoping someone might have an idea.