Skimming yer bed.... does anyone use a fly cutter?

[Jonathan]

The thing is about using a large end mill to level the machine bed, I'd rather not have a machine bed with a finish akin to this...

Why not? So long as you're spindle is properly trammed it's only an aesthetic problem, which should be last on the list of priorities.

(btw, what's the slowest a water cooled spindle can spin?)

Well it'll spin at a few hundred rpm, but it has virtually zero power available at that speed. The spindle torque (on a good drive) is approximately constant over the whole rpm range. The problem is power is torque multiplied by angular velocity, so as you reduce the speed the power reduces proportionately.