[xairflyer]

Does anyone know if there is anyway of knowing what the torque of a stepper motor is ?
I have got my hands on a few steppers recently that I can't get any data on

sanyo denki 103G714-1741 3.2A, 2.56v
Shinano Kenshi STH-54D403 1.2A, 8v

Also I generally thought that higher amp motors were more powerful yet the
Shinano Kenshi STH-56D309 2.4A, 2.88v one I have is rated at only 40ozins from what info I can find. I have a 1.2a motor with 80ozins so why would you use motors that draw more current ??

[Al_The_Man]

There are other factors that affect torque other than just current, voltage, current and stack length for a couple. The largest torque on a stepper is the maximum holding torque which occurs when the motor is stationary, so I would imagine if you energize the motor at the rated voltage and current to hold it stationary, you could measure the holding torque with a pulley attatched to the shaft with a cord around the pulley and a spring balance to measure the point at which it releases and calculate the oz-in figure as is used in other servo torque measuring methods.
Al

[Torsten]

The current applied to a motor minus its efficency equals a certain amount of work.
Torque is just one variable, to determine work you have to add speed to the formula.
I bet your motor delivers less torque but at much higher RPM's.
Some run only 300 RPM other motors do 6000 RPM big difference, you can always
gear the faster motor to get more torque.
Good Luck

[widgitmaster]

http://www.ee.ualberta.ca/~schmaus/elcts/mtest.html