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

Mariss,
OK that makes sense.
Inductance for series connection for the 445 oz-in motor is 21.6mH and the 3 stack version is 28.2mH
For parallel connection the figures are 5.4mH and 7.1mH .
I don't need super high speed, maximum would be in the 200-300 RPM .
Hans W

"Mariss Freimanis " wrote:

> Hans,
>
> It's not that simple. This is a subject that has wheels within
> wheels. That is what makes it so interesting to me.
>
> We were discussing low speed motor behavior, i.e. where the drive is
> limiting motor current. At high speeds the dynamic is entirely
> different.
>
> At high speeds what matters is motor inductance and power supply
> voltage. High speed in your case with your motor and supply voltage
> would be what happens above 10 revolutions per second.
>
> The dominant factor then is voltage divided by the square root of the
> motor inductance. That is what sets the maximum motor power output
> and is independent of low speed behavior.
>
> A 975 oz-in motor versus a 445 oz-in motor will certainly have higher
> inductance. It will certainly have more torque at low speed but it
> will have less power (speed times torque) at higher speeds.
>
> Mariss
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Hans Wedemeyer <xyz@h...>
> wrote:
> > Mariss,
> > Ok now I understand.... look for a 445 oz-in motor for sale on eBay
> sometime soon.
> > The next version of this motor has a holding torque of 975 oz-in
> for the same drive current.
> > As the current motor is marginal I'm hoping a 100% increase in rate
> holding torque will solve the problem.
> > What do yo think ?
> > Best Regards
> > Hans W
> >
> > "Mariss Freimanis " wrote:
> >
> > > Hans,
> > >
> > > You have missed the point and that is my fault. The moment a full-
> > > step driven motor takes a step, it moves the motor at a high
> velocity
> > > to the next step location (1.8 degrees away). This velocity is
> wasted
> > > energy and must be accounted for.
> > >
> > > A microstepping drive parcels out the "distance to move" in much
> > > smaller increments. Energy is mass times velocity squared divide
> by
> > > 2. If the distance to move is 1/10 as far, velocity will also be
> > > 1/10, and the energy invested in momentum will be 1/100 compared
> to a
> > > full-step drive.
> > >
> > > The step rate doesn't matter if it is 5 steps per second or 1 step
> > > per hour. The effect is the same.
> > >
> > > Mariss
> > >
> > > --- In CAD_CAM_EDM_DRO@yahoogroups.com, Hans Wedemeyer <xyz@h...>
> > > wrote:
> > > > 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
> > >
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