RE: [CAD_CAM_EDM_DRO] VFD for series 1 bridgeport

> -----Original Message-----
> After some searching of the archives I noticed it is recommended to
> have the G210's modified for use with Nema 42 steppers. Do I have to
> purchase these directly from Gecko?

Yes you need modified G201 or G210 drives to work properly. The way Mariss
explained it to me was that on the large motors you get too much feedback
for the midband stabilization and the stock drives will over compensate.
Mariss modifies the drive to decrease this feedback. The downside to the
modified drive is that it will not work properly on a NEMA 23 anymore as
they need the greater feedback.

To get the modified drives you do have to order directly from Gecko and
specify that they are to be modified for NEMA 42 motors.

> 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.

Tim
[Denver, CO]

> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/