Re: [CAD_CAM_EDM_DRO] Re: breakout boards plus - hard choice

Mariss used a 500 line encoder because in quadrature it matches his microstepper drivers 2000 counts per rev.
Dan Mauch
economical 3D scanner software and kits
low cost stepper and servo motors.
cases for Gecko drives
kits and assembled 3-4 axis drives
www.camtronics-cnc.com
www.seanet.com/~dmauch

----- Original Message -----
From: Jon Elson
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Thursday, July 19, 2007 10:08 AM
Subject: Re: [CAD_CAM_EDM_DRO] Re: breakout boards plus - hard choice


Mark Vaughan wrote:
> It may be possible to do this with a Grex, but that would require encoder
> feedback to the Grex, which is not part of the unstallable stepper
> philosophy.
>
I believe it HAS to have encoders to detect the phase angle
between the coil currents and the mechanical position. I am
very sure Mariss described having an encoder on the motor whiole
doing his experiments. Although it may be possible to detect
this phase angle from the voltage/.current pattern of the
motor's coils, I think it would be extremely difficult to do it
over a wide range of speeds, and practically impossible to do at
zero speed.
> The unstallable stepper just relies that if there is too much load
How can the drive know what the load is, except by the motor
being pushed away from the commanded position?

Jon




[Non-text portions of this message have been removed]