How do you check/test/measure step motor torque ?

[Calico]

I want to check that the step motor is real as it written but how ?
say it says 100oz, how can I test/measure in accurate way ?

how many ways can I measure without special/expensive tool ?

any website to get this info ?

rud

[limbo]

You can mount a lever of a certain length to the shaft. Clamp the stepper to your workbench and very slowly run it while the end of the lever presses on a kitchen scale. When it stalls you have your max. (holding) torque. Torque= "lever length" x "shown weight".

John

[Calico]

Thanks John,
How accurate is this cpmpare to the most accurate tool/measurement ?

90% ?

[limbo]

I guess its fairly reliable. I've tried it for a few known steppers and got within 80% or so of the manufacturers specified torque. On the other hand I think they sometimes are a bit "optimistic" in their torque specs. For instance some companies spec "holding torque" with max current through both phases while in practice max current flows only in one phase at a time.

John

[ISO Coder]

Originally Posted by limbo You can mount a lever of a certain length to the shaft. Clamp the stepper to your workbench and very slowly run it while the end of the lever presses on a kitchen scale. When it stalls you have your max. (holding) torque. Torque= "lever length" x "shown weight". John

Interesting,didnt know that,but is the lever length in Inch or mm and the same goes with the scale what units ?/ or is the formula the same if you use the metric system ?

[OCNC]

Originally Posted by ISO Coder Interesting,didnt know that,but is the lever length in Inch or mm and the same goes with the scale what units ?/ or is the formula the same if you use the metric system ?

Torque is a distance x force quantity so as long as your units are consistent within a particular measurement system (or as long as you use the appropriate conversion factors between systems) the results will be correct.

Chris