How to choose best gear ratio for desired RPM

[Ross Waddell]

I'm using stepper motors to spin small clear hemispherical domes in a model (weight: 5g) at a constant speed between 30-60 RPM using a TMC2208 SilentStepStick driver.

If the SilentStepStick documentation says the quietest mode is 1/16 steps what would be the best gear reduction ratio motor to use? I've done some calculations based on GM12-15BY micro motors (18deg step angle) and it seems like the lower the gear ratio, the lower the value for .setSpeed(x) [x=2400 is the practical limit for an Arduino Uno, I think]. Lower gear ratio also means fewer gear stages (at least, for 1/10) which might help further reduce noise (my big concern here).

Is there any downside to choosing lower gear ratios?

[Bob Remels]

Ron - one of the things I have found to reduce noise is the properly set the Vref via the little potentiometer on the driver. If too much current is being sent to the motor it tends to run rougher than necessary. 

Bob

[Ross Waddell]

Very true. I think I have the Vref set to the minimum without missing steps but the other advantage to 1/16 step mode is a smoother constant speed.

[Jim Larson]

You're  into an area that basically requires experimentation. There probably isn't a simple, one size fits all answer. Increased microstepping usually means less power to the gears, but an increased gear ratio compensates for that.

Sorry I can't be of more help.

                    -jim

[Ross Waddell]

That’s plenty of help, thanks Jim!

On Oct 11, 2024, at 11:58 PM, Jim Larson <jla...@pacifier.com> wrote:



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