Here is a link to a good diagram on the Kurt website:
What is the idea of the spring-loaded key on the "front" screw? It seems to me that the whole device would work perfectly well with that section of screw machined into the shaft like the other one is, and with all that collar, sleeve, thrust-bearing etc just omitted. So, what cleverness have Kurt designed-in that I don't get?
The keyway that the spring-loaded key fits into is actually two rounded slots next to each other, with the clockwise-rotation side (on the left-hand screw) ramped slightly.
Perhaps it would make more sense if I had the outboard section (nearest the handle) but that just looks to be there to hold a swarf shield?
Considering that a set of sliding and fixed jaws (parts 28 and 41? in the diagram) from Kurt costs more than I paid for the entire milling machine ($650) I am not entirely sure what to do with the vice. I am considering having some jaw castings made!