Re: [CAD_CAM_EDM_DRO] air bearing spindle

Elliot Burke wrote:

>I just bought one of the air bearing spindles that were being sold on ebay.
>It is marked as follows:
>Air Bearing LTD
>Model AW125E/04 Serial No 0328
>125,000 rpm (max)
>200V-2084 Hz - 3.0A (max)
>Made in England.
>
>Since a number of these were sold, maybe someone else on this list has one?
>Any idea how to hook one up?
>Looks like inputs for air and water as well as 6 wires coming out.
>
>

I have a Westwind air bearing drilling motor for PC board drills. It is
air-cooled,
and uses a LOT of air! I have run it up to 24,000 RPM with a standard
VFD. I
had to reprogram the VFD for 80 V @ 400 Hz. If you have a VFD that will
go to
400 Hz, you would set it for about 38 V @ 400 Hz. Then, you would have to
add inductors in series with each of the 3 motor lines, of about 2 - 3
mH each.
This is to compensate for the very low inductance of these motors. I'm
not sure
why your motor has 6 leads. It could be they brought out each end of each
phase so you could wire it either Wye or Delta. Or, some of the other wires
could be for temp sensing or some other function.

AC Tech has a VFD model with an option that goes to 1000 Hz. That would
get you
to 60,000 RPM. I may design my own VFD for several of these spindles I
have,
but it is not likely to happen real soon.

>There are no threads near the spindle nose, I'm not sure how the tools are
>held.
>
>

If it is for PC board drills, it will probably have a collet for 1/8"
shank tools.
My Westwind has a cnetrifugal collet.

>It is fairly heavy.
>Will try it out on my Taig mill, 125,000 rpm should do a good job engraving
>and cutting PC board.
>
>

Yes, it is basically solid steel, except for what is copper.

Note that a REBUILD of these units, with you supplying a rebuildable core,
go for around US $6000! I saw a price on a Kulicke & Soffa diamond saw
motor, a relatively similar unit, that was US $70,000!

Jon