Re: FS: New 4 axis microstepping driver $45.00 USD

Fred,

Good morning! A single-stack NEMA 23 motor has 1/15 the rotor inertia
of a triple-stack NEMA 34. Rotational energy at 600 RPM is 1/100 the
energy at 6000 RPM. Taking both into account means the stored energy
in the NEMA 34 motor was 1,500 times greater.

Scaling the 35 Joules (NEMA 34, 6000 RPM) of which 22 were returned
as electrical energy to a NEMA 23 at 600 RPM yeilds .014 Joules.

A Joule is also a Watt-Second. If the motor takes 0.01 seconds to
stall, then the returned energy is 1.4W for 0.01 seconds. 1.4W at 28V
is 0.05 Amps; this is probably much less than the power supply
current for an axis.

The net effect would be your axis power supply current would drop by
0.05A for 0.01 seconds. If it is 1 Amp, then it would have dropped to
0.95 Amps for 0.01 seconds. This would have no practical consequence.

Mariss





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Fred Smith" <imserv@v...>
wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis"
> <mariss92705@y...> wrote:
> > Fred,
> >
> > Probably very little. Energy stored goes up as the square of RPM,
> the
> > purpose for that speed is to simulate what gets stored in the
> > leadscrew, and to a lesser extent, the mass moved by the screw.

The

> > best way to tell is to run a single drive and scope the supply
> > voltage under actual running conditions.
>
> Hi Mariss,
>
> With the Sherlines and Taig machines, there is no coasting. When
> power is removed, the slides stop dead. They use 20 pitch V

threads

> for lead screws.
>
> I had someone with a scope handy run some tests.
>
> 18VAC 5 Amp rated transformer.
> The no load voltage was 27.2 vdc.
>
> Running a Nema 23 at 600 rpm, the voltage reading was 28.4
> Stalling the motor produced no change on the scope.
>
> We have 100 uf capacitors on each coil. (2 per axis) Do you suppose
> those are damping the peaks that would normally show up?
>
> Fred Smith - IMService
>
>
> > >
> > > > > >> On Wednesday, Mar 17, 2004, at 17:40 US/Eastern, Fred
> Smith
> > > > wrote:
> > > > > >>>> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Fred Smith"
> > > > > > <imserv@v... wrote:
> > > > > >We have a limited edition, 4 axis, microstepping driver
> > > > > >available for $45. Based on
> > > > > >the Allegro A3977 chip. The board is rated at 2 amps per

axis

> > > > > >and maximum of 35vdc. This is a promotional item and is
> > subject
> > > > > >to prior sale. Quantities are very limited.
> > > > > >>>
> > > > > >>> Info at: http://www.cadcamcadcam.com