Re: [CAD_CAM_EDM_DRO] Arc Welder Power Supply for steppers

JanRwl@... wrote:

>In a message dated 6/2/2003 10:43:42 AM Central Standard Time,
>sariddle@... writes:
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>>Another related question I have is on the rule of thumb I see often
>>of supplying 20-25 times the rated voltage on the stepper motor. Does
>>this always hold true and for all Volt steppers. The reason I ask is
>>that I see some steppers rated for 12V. This would yeild 240+V power
>>supply requirements. From what I understand this higher voltage is to
>>get better responce from the steppers. At what point do you limit the
>>voltage. One sure limiter is the driver boards voltage limit but are
>>there others?
>>
>>
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>Scott: A welder DC-supply is WAY-overkill, and there is likely some
>electrical detail of its design that will do damage or at least drive you nuts, when
>you attempt to use it for stepper power.
>
>

Yes, the leakage inductance is made high on purpose, to achieve current
limiting. this could cause huge voltage surges when motors stop.

>You might experiment and remove the TRANSFORMER from it, and try using the
>lowest-AC secondary to feed to a full-wave bridge rectifier and a capacitor of
>l0,000 or more µF.
>
>

Unfortunately, in all buzz-box welders, the current regulating is built
into the
magnetics of the transformer. For instance, in most of them, the lever that
sets current actually moves a piece of laminated iron around in the
transformer
core, to vary the air gap.

Jon