Re: [CAD_CAM_EDM_DRO] DC Motor types

a_k@... wrote:

> Hi all,
>
> I have a load of Field wound DC motors. Are these any good for CNC
> work (I have a pallet load of them).

Yes, I'm using them on my CNC system.

> I tried one this evening hooked
> up to a Gecko Drive it seemed to work ok, but was lacking in power I
> think.

Did you power the field? The correct way to run them for servo control
applications is to put a constant voltage on the field winding. It should
have a data plate to indicate proper field voltage.

> I have hooked it up through a bridge rectifer, with both fields
> hooked up in series going to the DC pos and neg, and then one of the
> armature windings going to one AC leg, the other armature going
> direct to power source and lastly the other power source going to the
> remaining AC leg.
> This makes the motor turn in both direction OK but is it good enough
> for CNC?????

I can't even figure out what you've done here. You should not need any
rectifier or other component. Depending on the DC supply voltage for the
servo amp, you might need a series resistor to provide the correct voltage
to the field winding. Wire it up as I mention above and see how it works.
(I don't know what you mean by AC leg - do you mean the motor output
terminals of the servo amp?)

Jon