I made a reversing jig to hold my big platters safely whilst skimming off the chuck-sockets, but it had one problem, the pressure pads which held the platter against the jig were shaped like the sort of buttons that are used under solid table tops to hold them down onto the table framework. These buttons could be fixed onto the jig to give a variable diameter in increments of about 2cm diameter, so, in theory, the platter could slip off centre if I had a 'catch' with a gouge.
I've overcome this by being wary of it, and cautiously taking very fine cuts, but this week I hit a possible further problem. I'd turned a 20" platter which had been in the house for a couple of months and had shrunk across the grain by 1cm, making the old buttons on my jig a bit risky for holding it in place centrally. Clearly I needed new buttons that were going to be adjustable, so I started playing with the idea of cams. The solution was very simple. I just turned a length of 3" square beech and made 5 buttons out of it, parted them off, then mounted them individually in my Patriot chuck and drilled them 2mm off-centre with a 6.5mm hole.
Next, I marked (with a pencil line) the overall diameter of the platter on the jig and fixed the cams in place with 6mm bolts, around the outside of the line. With the platter in place, all I had to do was turn the cams individually until the platter was as central as it could be, then tighten the cams down with wing nuts on the reverse side.
It worked a treat!
Les
