David,
I've had an HTC mobile base on my drill press for years. The style is
trapezoid shape with two lockable fixed wheels and a single caster
style wheel at the peak of the trapezoid. This configuration makes it
easy to rotate the drill away from the wall whenever I need to use it.
I have a piece of 3/4 inch plywood bolted to the base and then the
drill base bolted to the plywood. I works fine for me.

TWS