For serious woodturners a geared scroll chuck is the only choice. This high precision 4 jaw chuck uses just one T-bar to adjust the jaws which means mounting a workpiece is very simple and you will not run out of hands.
The basic chuck has thread size M33 x 3.5 for all other thread sizes an additional insert must be purchased. For most Charnwood lathes use insert W836ID 3/4" x 16tpi.
The chuck is supplied with an Index plate marked with 24 positions.

Two additional jaw sets are available. The Large jaw set expands from 98mm to 135mm and contracts from 119mm to 82mm.
The Small jaw set expands from 22mm to 59mm and contracts from 43mm to 6mm.