All good points, Phil, if this were for a precision machine cutting a hard material like steel.

It's going on to a table top router type machine though, intended to cut moulds for composite parts, from mainly EPS foam and MDF. The idea was to make something with a power similar to a small trim router or the larger Dremel type machines, but smaller in diameter, with more robust bearings, a better level of spindle accuracy and, most importantly, a much lower noise level.

If the whole machine turns out to be sufficiently accurate, I may use it for milling/drilling PCBs, although I suspect that the spindle speed will be too low for that task, so I may need to build another, faster, one.

If I get a spindle that is compact, quiet and comparable in accuracy and overall cost to a trim router then it will certainly meet my requirements.

Jeremy