Originally Posted by
Thomas Canfield
A loose fitting jam chuck/piece of scrap wood shaped to fit a ring of contact at about 1/3 or more of diameter of piece and a piece of rubber shelf liner, leather, or other soft pad will drive the piece with pressure of the live center in tailstock. You can then turn and finish the majority of the bottom leaving a small nub (diameter determined by quality of wood) that should be cut off with flush cut saw with protective material against bottom or chisel. Breaking off the nub can result in tearing out the bottom. Also care should be given to the pressure on the tailstock with a thin bottom.
This is the method I use as well. I do sometimes use a vacuum chuck but thin bottoms and open grain wood will suction air right through the bottom.
That is the reason to always leave a center point in the bottom to align for remounting. This jam method works for all sizes and even natural edge pieces. A modification of method with longer jam piece can be used on hollow forms when support of top.
This jam method works vacuum will not work due to worm holes, bark will not fit cole jaws, out of round will not fit a donut chuck, ..............
I use the jam and nub method mostly as well. Sometimes a vacuum chuck if the bottom isn't too thin.
Pete
* It's better to be a lion for a day than a sheep for life - Sister Elizabeth Kenny *
I think this equates nicely to wood turning as well . . . . .