What's the right size vise for a 12" Sherline 5400 mill with 15" column and head extension block?

[ChazzC]

ps: Wilton also makes a 3-axis 2-inch mill vise.
https://wiltontools.com/11700
It can tilt in two dimensions and swivel on its base.
Being able to tilt in two dimensions makes setting a compoud angle (an angle rotated around x-axis plus an angle rotated around the y-axis) easy.
A compound angle can also be obtained using the tilt in one dimension and the swivel base of a 2-axis vise, but it requires math (and mental gymnastics).
I have milled at compound angles to make tangential tool holders for my Sherline lathe.

These vises eat up an incredible amount of Z, which is very limited on small mills. While you can get extended columns on small mills, you are sacrificing rigidity particularly on the smallest mills that have a significant amount of weight at the head.