Re: VFD for series 1 bridgeport

> > The machine is missing the air-powered spindle control. I know

very

> > little about how these devices work. Thinking out loud, would it

be

> > possible to build a stepper-driven speed control that could be
> > interfaced with EMC? The gentleman I bought the machine from
> > suggested that I also use a VFD with the system. I'm not sure

why I

> > would need to.
>
> Yes you could put together a stepper driven system to control the

spindle

> speed instead of the original air driven. On the air system you just
> commanded it to increase or decrease the speed, you did not send it

a

> specific RPM.
>
> The reason for the suggestion of a VFD is that the machine is 3

phase.

> Unless you have 3 phase power you will need to convert your single

phase to

> 3 phase. A VFD is the best way to do this and it gives you the

added benefit

> of variable speed to boot. I started using a static and then a

rotary phase

> converter on my Bridgett (my Bridgeport Series II) and now have a

VFD

> instead. The VFD is the way to go.

Any recommendations for a good, cheap VFD? I didn't know they
convert to single phase. Cool! I do have a rotary phase converter
but will be purchasing a VFD soon.

If I'm understanding you correctly, Tim, the air motor stops and
starts on command, and thus the RPM only changes while the shaft of
the air motor is turning. So, could I put in a hand crank there and
leave the machine at a high RPM setting using the VFD to control
RPM? Then, whenever I need additional torque I could crank it down
but would still use the VFD to control RPM....????

Will the VFD brake the spindle motor also?

Thanks
Bob