When making a bowl on the lathe, one is eventually confronted with the choice of how to finish the bottom.

One common choice is to finish the bottom first, making a mortise to receive the lathe chuck in expansion mode. This, however, carries the risk of breaking the workpiece if over-expanded.

Another choice is to turn a tenon on the bottom to hold the workpiece, turn much of the outside and all of the inside, and then reverse the workpiece again to finish the bottom. This brings up the question of how to hold onto such a cumbersome piece.

Cole jaws are one option – they are like rather large chuck jaws. But they’re sometimes expensive, and requires changing out the jaws on a chuck. Australian woodturner Leslie Douglas Longworth came up with the idea for the so-called Longworth chuck.

While this was a cheap way to make a chuck for finishing the bottom of bowls, I found it to be very fiddly. I’ve never used cole jaws, but I would imagine that they’re more precise.

If making this, when it comes time to drill through the rubber stoppers, leave them in the freezer for several hours before doing so – that will greatly ease that process. Rubber doesn’t have a very high specific heat, so you do have to work quickly.