RE: [CAD_CAM_EDM_DRO] Re:305oz Steppers! More torque, Scotty!!!! (Shes' breaking up, I cannah hold'er)

I'll validate his statements as unbiased. What Ballendo is describing is THE
hardest part of the whole hobby CNC thing to get your head around.
Another more simplistic, way to look at it is that holding torque "power"
and axis speed often get mixed up in your head.
There definitely seems to be a point in time where the penny drops for the
more experienced pundits. Swapping your low torque motors for higher torque
motors at the same current will slow down your machine.

Mathematically:
Inductive reactance =2 x Pi x F x L
F= frequency
L= inductance

So for a given frequency, halving the inductance will halve the reactance,
double the current and double the torque

The magnetics of the motor alter this a little, this is why motors have
characteristic CURVES rather than lines, but there's no getting away from
the basics of it.

I've posted on this topic before, but from the perspective of ball screw
selection for small machines (routers and the like). Basically anything
finer than 10mm pitch will unnecessarily limit the rapid speed of the
machine. 20TPI screws on the Sherlines and Taigs would be better driven by a
step up drive, although the travels are so small that rapid speed is less of
a concern. Someone else pointed out that belt drives aren't far from an
optimal solution (again for small machines)

PK

> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of lcdpublishing
> Sent: Tuesday, 8 May 2007 6:01 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re:305oz Steppers! More torque,
> Scotty!!!! (Shes' breaking up, I cannah hold'er)
>
> Thanks for the info B,
>
> It appears as though your company has now grown to the point
> of having more than one employee (you used "We" in your reference to
> testing) and that you now have a valid, and well complimented
> lab with all the proper testing devices. In the spirit of
> how Mariss provides scope captures and other documentation to
> back up his statements, perhaps you too could post some data
> in a similar form.
> I would think that this additional information would help to
> validate your statements as unbiased (knowing that you are in
> business to compete with Hobby CNC).
>
> Thanks
>
> Chris