Re: [CAD_CAM_EDM_DRO] Re: Torque when using Micro Step or Full Step

Mariss,
The motor is brand new special made (spindle lengths) and guaranteed to be new because of that.
The spec. sheet only talks about Holding Torque and it's +- 10% so the 445 oz-in motor may already only be a 400 oz-in !
If Full step has an advantage at start up ( where my main problem is) If I used a control that allowed me to switch Full Step for startup and micro step for normal running, that may be a solution.
I'll consider that and see what I can come up with.
In Series mode this motor require 2.8Amp drive and I may be able to throw together a L6203/L297 circuit and do the Full Step/Half Step tomorrow.

I'll post results.
Best regards
Hans W



"Mariss Freimanis " wrote:

> Hans,
>
> The answer is somewhat involved so bear with me.
>
> Step motor mfgs list a holding torque for their motors. They do that
> because it is a universal specification that can be tested by anyone
> by applying a torque wrench to the motor.
>
> Holding torque by itself has little application in the real world
> except as a measure of comparison to other motors. A little-listed
> specification is dynamic torque. This is the torque a motor has when
> it is being driven by a full-step drive at 5 full-steps per second.
>
> Dynamic torque is usually 35 to 40% less then the holding torque.
> Where did the missing 35 to 40% go? It went to resonate the motor.
>
> A microstep drive starts off with a disadvantage regarding holding
> torque. It develops only 70.7% of the holding torque a full-step
> drive does.
>
> That is not where the action is though. It's "dynamic torque" loss is
> in the region of 3 to 4%. That is because compared to a full step
> drive, it invests less than 1% of its energy into resonance. Once the
> motor begins to move, tha microstep drive has the advantage an it
> keeps that advantage over the full speed range as well.
>
> Regarding your motor. Check carefully to see if it has not been
> disassembled. Look for marks on its screws. A step motor that has had
> its rotor removed from the stator can lose a lot of its rated torque
> due to demagnetization.
>
> Mariss
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Hans Wedemeyer <xyz@h...>
> wrote:
> > I'm still mulling over the lack of startup power this PACSI motor
> has , and was wondering if there
> > is much difference in torque output Micro Step and Full Step.
> >
> > The Gecko 201 only does micro-step.
> > Would there be any increase in torque using Full Step as compared
> to Micro Step ?
> >
> > Best Regards
> > Hans W
>
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