Hi John.
I'll try to describe it. The spindle has a female B&S taper ( around 5 MT ) with a female square at its nose.
The " tool carrier " fits snugly into this and is held in place by the round knurled locking nut. A smaller, fine threaded nut ( large Clarkson spanner size ) is brought up against the locknut to stop the assembly from undoing whilst running.
The milling chuck fits into the internal taper and held firm by the short " drawbar " through the end of the carrier. Once tight the assembly is offered up to the spindle, located into the square and locked in place using a " C " spanner. The smaller locknut is tightened to finish.
Though rather tedious in setting up the accuracy is very good and rigidity excellent.
If you look closely at the photograph you might discern a crack emanating from the Tang release slot? It's not a crack, it's broken in half. The thickness of this area is measured in 1000's of an inch and a repair with either a weld or hard solder impossible.
The machine is a number 20, stands over 8 feet tall and is getting on towards 2 Tons in weight. The original motor had multiple winding combinations for speed change but when it burned out I replaced it with a 4 pole 3 phase motor and used a VFD instead.
It's been one of the most versatile machines I've owned, hats off to WB Knight. I was hoping that one of our many " over the pond " members/readers might know if there's some replacement tooling available?
Cheers Graham.