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

At 12:38 PM 12/29/02 +0000, Tony Jeffree wrote:

>At 11:47 29/12/2002 +0000, you wrote:
>> >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?
>>
>>I had the same problem.
>>Obviously it's noise from the Sherline DC motor.
>>
>>Tried wrapping the Sherline motor cable in aluminum foil (!),
>>putting a snap-on ferrite bead on the power line,
>>plugging sherline into different outlet, etc. Nothing worked.
>>
>>What fixed it was R-C filters on the step-input to the stepper drivers.
>
>What values of R and C did you use?

I happened to have a bunch of 68pf caps laying around, so I used
that for the "C" and a 4.7K for the "R".

I think any 1K to 10K resistor, and any capacitor < 0.01uF would
work fine as well.


- Dom