My community hackerspace has a used Kuka robot arm. I have successfully programmed it to make cuts in foam with a Hitachi woodworking router, now I want to get a beefier, water-cooled spindle.

I was thinking about buying some long (10") carving tools from Frog tools, but they can't seem to give me a recommendation about what kind of spindle to buy; all they will say is that their tools should NOT exceed 6000 RPM.

I would like it to be water cooled, as there is a lot of foam dust/shavings being generated, and my Hitachi router has already shorted out twice from shavings getting inside.

A lot of the spindles I've seen on eBay say they start at 8,000 RPM....but doesn't the starting speed depend solely on the variable frequency drive used?

Thanks for any advice!