Proxxon MF70 experiences or alternatives? The Home Shop Machinist ...
Most of these units were used in the PCB drilling and milling business and have a 1/8" chuck. High speed, great runout, but often are bulky. Remember that these air bearing spindles may take a lot of air. Depending on the size of your mill, you might be able to use a spindle speeder or an air powered spindle designed to mount in your mill spindle.