Re: [CAD_CAM_EDM_DRO] Re: Novice - Stepper Motor questions

Lyle Cox wrote:

> How could I test a surplus stepper motor for torque ? (oz inch)
>
> When a stepper motor has a rating of NN oz inches, is that holding
> or
> turning torque? (or is holding and turning torque the same on stepper
> motors?)

The motors are usually rated at holding torque, because that is the
biggest number.
But, if you can get the detailed manufacturer's data sheet, it often
will list running
torque at some speed, or give a graph of running torque over some speed
range.
There, you will see how quickly running torque declines as speed
increases.

The difficulty with this is this decline is HEAVILY driver dependent, so
often
they will list a specific driver, or at least a specific stepping
sequence (half
step, full step, etc.) and a driver type (single ended vs. full bridge,
etc.) and voltage.

The 8 wire motors give you the most flexibility in how to wire up the
windings,
but you will find that a full-bridge drive on an 8-wire motor with the
winding sets
in parallel will almost always give the best speed performance, as this
allows
the most effective use of the driver voltage and the lowest inductance.
This
setup is also the most costly (twice as many transistors, and the
highest
currents).

Jon