Not a full enclosure but the table has a guard round three sides, the front having a removable perspex door, so no oil skins required
I have a DA pencil collet that I was contemplating using as a spindle but that ER is a great price.
Hood, beware of these Chinese collet holders. Bought few BT30 holders (from another Chinese seller though) and accuracy is not something these were built for. The quoted 0.01mm runout appeared to be not the worst case like you'd expect, but the best tolerance they can achieve. Actual runout measured on 5 holders ranged from about 0.02mm to 0.25mm (I didn't miss a zero there)!!!
Did make up a spindle speeder of sorts which was geared via a toothed belt but it got too hot to touch after about 3 mins running and the heat seemed to be coming from the belt friction on the pulleys, was thinking of directing some coolant through the body but not sure how the bearings would like it, would have to filter it and may give it a go.
Round tooth profile belts perform better at higher speeds. They engage better with the pulley, with less friction, and thus less heat (and noise) is produced. But I assume this is what you already have... What speed are you running the driving pulley at? And what diameter is it? I have 75mm diameter pulley that would run for hours at 3500RPM without getting that hot. I am sure I could run it even at 5000RPM much more than 3 minutes and not get that hot. May be check the tension?
Anyway, the best choice for a high speed application is a V-belt, or any belt other than timing belts. Or put it another way, timing belts are least suitable for high speed applications because their teeth engagement and disengagement with the pulley teeth produce a lot of noise and heat at high speeds. You don't really need a timing belt there - no angular positioning needed and no big moments to be transferred - so may be put a V-belt or even an O-ring belt and see if it helps. It really should, unless there is another source for the heat.