Re: [CAD_CAM_EDM_DRO] High speed spindle chuck

Smoke wrote:

> Sounds like a good idea to adapt that air powered hand engraver tool then.
> It uses collets and runs at...hey, I forget exactly what mine runs at but I
> do recall it's in the >100,000 range.
>
> I do you get the CNC to peck drill 4 or 5 holes a sec. You'd really need
> some fast X-Y feed rates.

Well, remember that when drilling PC boards, the plunge feed never exceeds
about 1 Lb force, there is practically no side force, the part being machined
might weigh 1 Lb, tops, for a small stack of very large boards. The machine table
might weigh a couple of pounds, and Excellon tables float on an air bearing.
So, the inertia and friction loads are nil. The air bearing, integral motor-spindle
weighs about 6 Lbs., so a fast stroke is pretty easily achieved. The disadvantage
to air turbine spindles is that the speed is not constant under load, unless
thay have a governor on them, which the most expensive ones do, indeed,
have. Mine has a 3 phase induction motor, but needs high frequency power.

Jon