Using a 1725 rpm motor..its normal to set the high side at 120 hz. Which gives you nearly 3000 rpm at the motor..no issues known.
With a mill..gearing up and down using the change pulleys gives you the best of both worlds. Figure the speed and feeds of a 3/16" endmill. ..you NEED those high RPMs with small cutters. Bridgeport spindles are rated for 5000 rmp. Take advantage of it.
Gunner
"Try thinking of the Libertarian Party as a rolled-up newspaper, useful in making the Republican puppy (I've given up on the Democratic bitch) go where he's supposed to -- not on that beautiful antique carpet we call the Constitution." -- L. Neil Smith, Bill Clinton's Reichstag Fire