RE: [CAD_CAM_EDM_DRO] Aaah! (Magically Moving Steppers)

I am not a big fan of using switched power supplies because they can
introduce some strange problems that are hard to track down. I know,
some people have them working just fine.

The first step I would take would be to use a good old fashion linear
supply and see what happens. It may not have any positive effect, but it
will at least eliminate a possible problem.

You don't mention how your electronics are mounted, but I would get them
into a metal box so they are shielded from any RF that the Sherline
speed control is putting out. You could also be getting noise from the
motor brushes.

Tim
[Denver CO]
Sherline Products at Deep Discount
Mach1 & DeskCNC with Credit Card ordering
Contact me for discounts on DeskCNC & Sherline bundles
www.KTMarketing.com/Sherline

> -----Original Message-----
> From: abbylynx <abbylynx@...> [mailto:abbylynx@...]
> Sent: Saturday, December 28, 2002 8:30 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Aaah! (Magically Moving Steppers)
>
>
> Aaah! I spent some time trying to fix a problem with my parts coming
> out lobsided, and just believe I may have found it.
>
> My system is on, then I turn on the Spindle of the Sherline, turn it
> up to max. The Sherline spindle is not connected to the CNC system,
> it's the plain old power switch on the spindle of the mill.. I turn
> the speed control up to max.
>
> I then watch the rear-shafts of the motors, and though they were
> holding still before, they now roll back and forth every few seconds
> by a small amount. Aaah! I'm thinking this is due to induced mains
> hum throwing the dir/step pins. Any advice?
>
> My system is a little limited still, so it's basically:
>
> Xylotex driver board
> Switched Mode PC power supply (12V driving the steppers)
> BF Cap 47,000uf
> Some big NEMA23 steppers
>
> Could it be the switched mode power supply in some way? It driving
> the logic also, I understand that switched mode PSU's employ PWM to
> provide the correct power level (just like a chopper board), could
> this be interefering with the system?
>
> Any advice greatly appreciated.
>
>
>
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