RE: [CAD_CAM_EDM_DRO] Interference?

KB Electronics makes a good line of speed controls, just to be clear though
the KBWM-240 is an SCR variable speed DC motor control not a servo control.
More to you point on the interference issue. Motors in general cause lots of
interference issues and electronics speed controls cause even more. The
first line of defense is to use a line filter on the mains fitted just
before your speed control, this will keep the noise generated by the speed
control/motor from traveling back down the mains into your controls. Your
wiring layout and earth grounding system can also play a large part in a
stable system.



This is the type of line filter I'm referring too:
http://www.soigeneris.com/10A_Line_Filter_Kit-details.aspx (warning this is
a link to my website), you might find a similar unit in something like an
old photocopier as well. You might also have an electronics supplier in your
area that carries a similar item.



Jeff Birt

Soigeneris.com



From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Keith
Sent: Monday, November 22, 2010 3:48 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Interference?





Hi Folks.

Yesterday, I changed the motor driving my milling spindle. Originally, I had
an AC 1/4HP motor running at a constant speed of 1425rpm, with step pulleys
to change the spindle speed.

I replaced this (perfectly good motor) with a DC Servo motor, with a
variable speed control. The replacement motor is a Dynetic Systems model
318032, whilst the speed controller is a KB PentaPower Vari-Drive unit Model
KBM240.

Immediately I started to use the system with the new motor in place, my
stepper motors started 'twitching' and making erroneous movements, resulting
in what should be, for example, a straight cut becoming a diagonal, with
associated increases in the Z moves simultaneously. I can only assume that
the new power unit is producing interference signals, which are affecting
the control of the steppers.

What actions can I take to eradicate this interference?

Keith





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