I am thinking on incorporating planetary gears to a project where I use nema 17 steppers.

I have been looking around information on planetary gears. Although I understand the principle under they work, I cannot grasp all the details, so I wanted to open the discussion here in more familiar terms.

My main doubt is, using as an example a planetary gearbox with ratio 100:1, which of this statements are true?

-the spinning rotation of the shaft of the planetary gear will be 100 times slower than the shaft of the stepper

-for each step of the stepper, there are 100 steps of the planetary gearbox, which means that the rotation will be much smoother, like having 1/100 microsteps?

And what happens with the torque?

thanks for sharing your knowledge!

Planetary gear / epicyclic gear system is deign for heavy load and specially to handle the variable load.

Output of the gearbox will handle more torque than motor.

And what happens with the torque?

The torque is multiplied by the same ratio that the speed is divided. At 100:1 the output shaft turns 1 step for every 100 motor steps with 100 times the stepper torque (minus gearbox frictional losses).

so the second statement is not completely true?

-for each step of the stepper, there are 100 steps of the planetary gearbox, which means that the rotation will be much smoother, like having 1/100 microsteps?

For each 100 steps of the stepper there is 1 step of the planetary box. but the the rotation will be much smoother, like having 1/100 microsteps?

Or to say it another way, with a 200 step per revolution motor, the output shaft will turn 3.6 degrees for every 360 degrees of stepper rotation. I would think that the output shaft rotation would *appear* much smoother, but testing will tell.

camilozk:

so the second statement is not completely true?

-for each step of the stepper, there are 100 steps of the planetary gearbox, which means that the rotation will be much smoother, like having 1/100 microsteps?

For each 100 steps of the stepper there is 1 step of the planetary box. but the the rotation will be much smoother, like having 1/100 microsteps?

The gearbox doesn't have steps of it's own accord.

If you move the input by one step (of the motor), then the output will move by one step too. But that step will be much smaller. (1/100 the size)