Hi Speed Spindle for Series II 4HP head with Erikson 40 (NMTB 40) or Quick Change 40

[SCMW]

Hi,

We recently purchased some Bridgeport Series II NC Machines with 4HP heads (6000 pounders, not the 2000 pound original BP variety) that have been converted to Mach3 with steppers. While we still have to move them into the shop (another question to that later), I'm starting to collect info regarding upgrades that I intend to make to these machines.

These brutes have the NMTB 40 or Erikson 40 taper (40 quick change) toolholding system.These machines will do a fine job for our purposes. However I'm looking for a way to expand upon their capabilities. Currently the high end goes up to 3500 RPM. As an example, we sometimes mill details into model parts using 45-75 LB density tooling board or 6061 aluminum with miniature flat and ball end mills running from .040" down to .005". Usually I'll take .001-.003" off in a typical pass as we're basically running profiles. The tooling for the most part is .125" shank on these smaller cutters. Our benchtop mill (A2Z/Sherline Frankenmill) can handle 10K RPM with no problem but the work envelope is much smaller (the main reason for buying the BP's).

I'd like to find a way to do the same with our new (well, new to us) BP's. Can anyone suggest a good high speed spindle that will fit Erickson 40 taper tool holders? I'd like to hit speeds of at least 12K RPM and possibly go up to 24K RPM or higher.

My main concern is durability. I'd like to find a solution that lasts and can be rebuilt when it fails. It could be air, electric, or mechanical. What are the benefits of one type vs. the other.

Thanks,
Terry