Re: [CAD_CAM_EDM_DRO] DC motor as replacement for Stepper motor

At 11:20 AM 1/22/02 -0700, you wrote:

>Thanks...I think.
>
>Does this mean the DC motor would step in 1.8 degree increments or would it
>"step" in whatever degree increments you wanted based on the electronics?

It is limited by the encoder feedback, to integral steps if it is a quadrature
digital encoder. If you have a 500 counts/rotation encoder on the shaft, you
could get 0.72' or any integral multiple of that. 1.8 degree is 200 steps/
rotation so you could use any integral multiple of 200 (200, 400, 600 etc.).

>How accurate would it be in this regard?

Depends mostly on the encoder (assuming a PID controller).

>If you could vary the step increments and hold the accuracy, it seems to me
>one might just as well forget about using steppers altogether

Steppers will be cheaper and simpler for something like a Sherline, I think.
You don't really want to control the shaft position usually, and backlash
and nonlinearity after the motor shaft will affect your accuracy. Better to
get the feedback from the actual thing being moved, I think.

Best regards,

Spehro Pefhany --"it's the network..." "The Journey is the reward"
speff@... Info for manufacturers: http://www.trexon.com
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