Researching how to make my own tool holder (having seen the price of them). The mill I have access to uses an ISO40 taper. ISO. Excellent that's gonna be metric and sensible and... no wait... Wtf. ISO taper angle is 8.2971° (relative to the centre line of the piece).
What uncultured barbarian idiot came up with such a number...
Oh right, it's grandfathered from imperial 3.5" in a foot, or a 7:24 ratio. Sigh
