Re: Cheap 56,000RPM milling upgrade (not a dremel :)

> The bearings are AIR! No balls; steel, ceramic or other. The

spindle

> flies on a
> cushion of air, and only air. Technically, a "fluid film bearing"

in

> which the fluid
> is dry, filtered air. Rather amazing, the friction is about 1
> ten-thousandth of an oil-journal
> bearing, and about 1/1000th of a fine ball bearing. If the

clearance in

> the bearing can be
> held to a fine tolerance, the stiffness can actually be GREATER

than a

> ball bearing,
> which is still pretty hard to comprehend.
>
> Jon

Do you know approximately what the shaft diameter is, were it is
supported by the air bearings. And what is the rated continuous
running RPM of this unit.


Wally

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
> cnc_4_me wrote:
>
> >Good post Jon. I was looking for a answer that would give me a
clue
> >to its construction. I asked the question rather badly but you
still
> >gave me a good answer.
> >
> >P.S. My jaw dropped when you said $6000.00 spindle. I suspect
they
> >are not using ceramic roller skate bearings.
> >
> >
> Now, of course, I *didn't* pay $6000 for the thing. Actually, I
paid $300
> about 20 years ago for two of these spindles (No, I will not sell
the
> other one)
> and the high precision ballscrews that are now on my mill. I
wanted all
> the mechanical
> parts I could get off the Excellon NC drilling machine. I did
*NOT*
> want the ancient
> NC control - 500 paper-phenolic circuit boards covered with
germanium
> transistors!
> UGHHH!
>
> Actually, I have no idea what these spindles are worth. Some of
the
> later water-cooled
> models have a $6000 CORE CHARGE when they do a rebuild!
>
> A slightly bigger Kulicke & Soffa motor for a diamond wafer saw had
a price
> tag of $75,000! Saw that at an auction.
>
> The bearings are AIR! No balls; steel, ceramic or other. The
spindle
> flies on a
> cushion of air, and only air. Technically, a "fluid film bearing"
in
> which the fluid
> is dry, filtered air. Rather amazing, the friction is about 1
> ten-thousandth of an oil-journal
> bearing, and about 1/1000th of a fine ball bearing. If the
clearance in
> the bearing can be
> held to a fine tolerance, the stiffness can actually be GREATER
than a
> ball bearing,
> which is still pretty hard to comprehend.
>
> Jon