I suspect, but am not certain, that it is a simple type of small expanding chuck ?
Drill a hole in the timber to be mounted using a forstner bit, or maybe a spade bit, would need to be a close fit. Mount the chuck in the headstock spindle and lock the spindle in position.
Mount the drilled workpiece onto the chuck and expand the grooved section by turning the wide shaft section with a spanner ( it looks like there are spanner flats on it but can't quite see) until a tight/solid fit.
Unlock headstock spindle and start up lathe slowly and standing well back :lol:
Not a daft question at all. Paulm gave the correct answer.
It's a Mini Gripper chuck from Craft Supplies (no longer available it would seem), which came in either 1 or 2 morse taper versions or with a 3/4"x16 thread.
I use the threaded version to turn 12" out of round blanks (started with tailstock support). I regularly use it to turn 6" to 9", natural edged, oval bowls & highly recommend it for its gripping power in both wet & dry woods.
IIRC it requires 1 1/4" (32mm) recess cut with a forstner or sawtooth bit, to the depth of the jaws. Don't go too deep or you won't get a spanner on the flats to remove it.
I originally had some qualms that the morse taper version might slip in the headstock when turning out of balance pieces but thinking about it, support from the tailstock would probably prevent any slipping or other movement.
I would go as far as saying that IMHO the grip on this chuck is so good that it is completely suitable for a beginner.
I have an MT1 version and there is a draw-bar thread in the rear (M6) which means that tailstock support isn't needed. Use a cheap length of threaded rod and washer/wingnut on the back to prevent it coming out of the taper.
The roll-pin just prevents the serated jaws rotating with the body of the chuck - locking one of them to the countersunk screw down the middle. I don't think it's much longer than about 10mm.
I used to use it quite a bit before I invested in a proper scroll chuck but it's a very handy because the chucking point is quickly made off the lathe with a 1 1/4" Forstner.
The rollpin on mine, if you can call it that as it's just a bit of rod snipped off with cutters, is 8mm long & 2.5mm ø.
The M6 thread goes all the way through the chuck body, but so does the bolt. To use it with a draw bar as chipmunk says, you need to have a hollow headstock & to shorten the bolt. Unless the morse taper chucks are different & have shorter bolts, I suspect that the through hole was for ease of production rather than a design feature. Either way, it's an extra capability for a super little chuck.