Re: [CAD_CAM_EDM_DRO] converting Bridgeport powerfeed to CNC DC servo

> Considering the relative ease to add, and low cost
> that a Bridgeport table powerfeed costs (both X & Y &knee),
> has anyone taken one apart to see what kind of motor is
> in there? Probably AC.
>
> Can it be replaced with a similar size DC motor,
> and then be run from a G340? An encoder needs
> to be added, obviously.
>

I don't think they are that cheap actually, plus you have to add the
cost of a new motor. I believe they also have backlash, since they
aren't designed to reverse during a cut. And given the high reduction
you won't have a rapid speed to speak of.

It's probably simpler to buy a large DC motor, bore a timing belt
sprocket to fit under the crank, and go with a real servo that will
give you a meaningful rapid. You can put the encoder on the servo if
there is no room to fit it on the screw.

I was given some old slow-syn type steppers, and someday when I have
nothing better to do will cobble together a simple non-chopping
unipolar drive to use them for programmable power feed - ie, position
the table by hand and then just tell it to move so far at such and
such a speed. One could do that with an unmodified bolt on power feed,
simply using a solid state relay to shut it off.

Chris