We had a discussion earlier today about having the collet directly in the spindle, which was my idea to keep it simple and cheap.
There's no problem making a spindle for that, the most expensive task would be the fine grinding of the cone (the Ra-value is very low). But the problem would be hardening and steel quality, wear of the cone surface will make the collet to "ride". I can by a brand new ISO40 or SK40 chuck for less than 100USD and then I'll have everything I need (hardening and grinding done, fastener, release tool etc.) and the chuck cone in the spindle doesn't need the perfectness as the collet cone. Also, if something breaks the spindle won't be damaged and I can decide later to change the tool holder if needed, when I buy an High speed-gearbox.
I just found a bunch of chucks at eBay for very nice prices, and it doesn't really matter which cone to use as long as there are collets to buy.
For you guys interested in making a spindle with a collet chuck there's a simple way to make perfect matching cones. Buy a spindle, set it up in a lathe and fine tune it to the centre, press the tool holder aginst the cone and voilá - you've got your cone angle.
Anyway, within a couple of days I have the standards in my snail-mailbox and I'll publish them as soon as possible.
Cheers,
Sven