Re: [CAD_CAM_EDM_DRO] Hi frequency inverters and spindles

ddgman2001 wrote:

>If possible I'd like to piece together a Colombo or Perske system of
>spindle and high frequency inverter.
>
>Is this a fairly straightforward request or are there intricacies
>involved beyond matching HP rating, voltage and phase?
>
>Am I better off ordering all from one manufacturer or supplier?
>
>

Yes, until you get to the price part. better be sitting down.

I have a Westwind air bearing drilling spindle, which is mercifully
3-phase, and I have gotten it to run on a standard VFD. I had to add
inductors to the output, between VFD and motor, because the motor
is such a low inductance. My VFD only goes up to 400 Hz, so I am
limited to 24,000 RPM. Some VFDs, such as AC Tech, have options
allowing them to run up to 1000 Hz.

But, my Precise ball bearing spindle is a TWO Phase motor, and a standard
VFD will not drive it. There is a scheme, called a Scott T that will
convert
from 2 to 3 phase and vice versa. Someday, I will have to try hooking this
up and see if I can make it work.

So, the first order of business is to find out what type of winding is
used on the spindle. Then, you need to get the Volts/Hz factor for the
motor, if possible. If you can't get this, it is possible to "feel" it
out using the VFD and motor, and making educated guesses. I had
to do this with the Westwind, as they couldn't match up the serial
and model numbers on the unit with anything in their records.
I ended up getting it to work at 80 V/400 Hz. Strangely, if I set it
for 75 V/400 Hz, the VFD would fault out while accelerating.
A quirk in the VFD's firmware, I guess.

Jon