I have 3 systems.
Using my 4" Patriot jaws I have a 9" disk, out of 2" material. I often just press the bowl against the disk, using the revolving tail centre to hold it in place. If it's a delicate bowl or if there's tricky grain, I sometimes cut a groove in the wooden disk just to set the rim of the bowl into.
I also have a 22" diameter 3/4" plywood disk which has a 6" faceplate permanently set on the back of it, although a faceplate ring which fits your chuck would also suffice. With this system I almost invariably use piece of router matting between the bowl and the disk.
Each of these systems work between centres.
For larger stuff, too big to fit over the bed ways, I swing the headstock around and fit a 36" diameter disk. this disk has concentric circles marked on it, about 1cm apart and also has a set of 8 lines, each marked along a radius and set at 45degrees to each other. Each radius has a series of holes drilled along it, into which I set wooden buttons, held on with set-screws ans nuts/washers. Each button is a mushroom shape, its head being somewhat larger diam than its base. The hole through each button has been drilled off-centre, effectively making each button a cam. I set the bowl/platter against the disk, bolt the buttons into place and give them the odd twist to jiggle the platter about until it is centred up properly....it works for me!
I used to persevere with all manner of cole jaws/reversing jaws and expanding/spiral disks....but dumped them all in the storeroom in favour of the above, which is a lot quicker to use.
Les
