Paul wrote:

We do need something fast as a lot of material is removed.
Especially on something large like a 3D contoured bell housing pattern.
Many many tool paths are involved to get the smooth surface finish

necessary.

You won't machine anything at 300 IPM, at least not with that spindle.
With your spindle turning 7000 RPM, 300IPM would be a feed per tooth of
0.020" on a two flute mill.  For an end mill in Alloy you are looking at a
max of about 0.011", less for a ball.

With a 1/4" ball end mill, you would be looking at about 548 SFM, which is a
low for alloy .

Drive a 1/4" ball though foam at 0.020" feed and 548 SFM, and you will just
tear it apart, not cut.

In practice, you will machine far below the rapid speeds of the machine, so
whether the machine can do 300 IPM rapids, or only 120 IPM rapids won't make
much difference in run time.

To do high speed machine you would need a much faster spindle, and an
effective cooling system.

Regards,
Mark

Let me see if I understand what is going on here. It is up to the PC Intel processor 
to repetitively send 3 bits through the parallel port  that move the 3 axis's, .00001 
inch each, at rates that result in smooth 3D motion. This is why feed rate is limited. 
Correct? The Geckos receive these bit rates and convert them to analog voltages +/-
70 Volts for the servos. This is done in hardware (resister-capacitor 
integrators and amps) with no processors on the Geckos. Correct?

If so what are typical bit rates for 1 gig processors running DOS?
 
Paul Lamar
 
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