Re: [CAD_CAM_EDM_DRO] Stepper Question (Newby)

> He everyone. I have finally got my Taig Mill hooked up using the
> Stepperworld FET-3 and 150oz stepper motors. Everything seems to move
> correctly however I can very easily hold the other end of the motor
> shaft to stop movement. The motor seems to hum as if something inside
> is moving but the shaft is not.
>
> Anyone have a clue as to whats happening. I don't think that I should
> be able to stop a 150oz stepper motor that easily.

The humming you are hearing is just from coils in the stepper. There
is only one moving part, and that is the rotor - I would consider it
fairly unlikely for that to have come loose from the shaft.

Good stepper drivers regulate current by turning the coil on and off
extremely rapidly, which does produce some humming. Often this is a
frequency above what you can hear, however not always. One widely
popular circuits has a common failure mode where the freqency drops
quite a bit below what it is designed to be, and torque suffers as the
duty cycle is also messed up.

The problem may be far simpler and more fundamental though: many
(actually most) inexpensive stepper drives are limited to 2 or 3 amps,
and so cannot supply enough current to run a 150 oz/in motor which is
optomized for high speed operation (ie, has a high current low voltage
winding).

So, either check your drive setup, and if that fails, spend the money
on a good driver that can supply rated current to your motors. Make
sure your power supply is up to the task, too.

Chris Stratton