Re: [CAD_CAM_EDM_DRO] High Speed Spindle

In a message dated 10/26/2004 11:44:14 PM Central Standard Time,
keithlmartin@... writes:

I was wondering if it would be worth while putting two bearings at the
collet end with a small preload on them and a single floating on the pulley end?
<<
Yes. By all means. The "housing I.D." should be exactly the same as the
bearing O.D. so that they are an "interference fit" (not quite "press-fit").
Even 5 tenths oversize is too much. UNLESS you have some kind of face-flange
that screws down over the outer race, to "clamp" 'em in place. Which is
probably the best way to mount 'em, anyway! In that case, make a "shim washer"
of 0.001" or 0.002" shim stock and place that between the two inner races, to
create JUST the right pre-load.

I am GUESSING you intend to use a belt-drive to a parallel motor? I made a
"direct drive" quill for MY PC-drill with a 95 W. 400 Hz. motor that turns
12,000 RPM. NICE! (Had to build electronic 400 Hz. generator, so was useful
to be able to wind my own transformers for that). I replaced the "output
shaft" and bearing with an ABEC-y 7/16" I.D. bearing and a custom-made collet, so
that the 1/8" shank bits fit right into the "end of the motor shaft", with a
collet-nut to hold 'em tight. Remember: At that RPM, one MUST work
fastideously precise!!!
(Yes, I'd RATHER have a 24,000 RPM motor, but can't have it ALL in
"home-brew", I guess!)

Jan Rowland




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