Re: [CAD_CAM_EDM_DRO] Re: High Speed Spindle - what speed ?

In a message dated 8/14/2006 10:58:28 P.M. Central Daylight Time,
dave_mucha@... writes:

It seems that there is a desire to get to 20,000 RPM and above, but is there
a real need for it ?<<
Professional CNC PCB drills spin on up to at least 100,000 RPM, if not
300,000, but I'm not sure of this latter figure. I only READ it somewhere I have
now forgotten, so I have also lost if this was a "hopeful, someday" figure,
or what.

I have a home-brew direct-drive quill with a 12,000 RPM 3-phase 400 Hz.
"aircraft instrument motor" and that plunges into the FR4 at a rate of about
0.001 inch per revolution. All the engineering was "first-time GUESSING", but it
seems OK. But I'd much rather have a 24,000 RPM motor, but none was to be
had in the "junk store".

Anyone have a speed range they find is best for the 1/8" and 3/16" cutters
?<<
PCB "standard solid-CB drills" have 1/8" shanks, but I DO realize some bits,
both drills and routers, etc. are larger, but with the same 1/8" shank. If
you mean the "cutting diameter" I would want the 1/8" dia. spinning at least
24,000 RPM, but the 3/16" MIGHT work with careful feed-rate at lower speed.
Don't really know. Better would be on up 50,000 or more!

You using a solid-rubber "O-ring" for the belt on your spindle? A V-belt
would be very rough, and the vibration would SURELY eat tiny PCB bits for
breakfast!

Jan Rowland








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