RE: [CAD_CAM_EDM_DRO] Motor woes

The main reason your are getting such slow rapids is that the motors you
are using are very high inductance. For good rapid performance you want
to get motors that are rated 1.X - the low 2.X volt range. They will
have resistances in the very low single digit area. Another problem is
that a non-chopper unipolar drive is not a high performance drive. It
will certainly work, but you will not see the rapid speeds you can get
from something like a Gecko chopper type drive running at 60 - 70 v.

The tutorial that someone just referenced on stepperworld is pretty good
to explain a chopper drive.

Tim
[Denver, CO]

> Has anybody used Astrosyn 8 wire T180 universal motors?
>
> Specs are as follows - 12v 0.6 amp/phase Res 20 Ohm/phase
> Inductance 35mH/phase Torque 5.5Kg-cm.
>
> I can't get the damn things to run at anything above a crawl
> without missing steps!!
>
> I'm running them in unipolar mode with a home built
> controller based on UDN5804B's
>
> Can anybody recommend some reasonably priced size 23 motors
> available in the UK - I'm looking for between 5-7Kg-cm
> holding torque, but with a reasonable turn of speed.
>
> I want to use .2" lead screws but get better than 12 inches a
> minute (which is all these will do).
>
> --
> Steve Blackmore
> steve@...