Bowl reversing jaws are useful to hold some kinds of bowls by their rims while you finish turning their foot. You can buy sets ready for use, but I recently made my own. I screwed plywood quadrants to steel carrier plates like these that match my chuck. I fixed movable pegs to the quadrants. The pegs form a circle that grips the rim of the bowl. I did the final turning of some of the bowls I sell here using this homemade kit.
The first pegs I tried were pre-drilled rubber bungs from a home-brewing supplier. They have a taper, which gives them a dovetail grip. I drilled holes in concentric circles on the quadrants and fitted 8 mm tee nuts (the kind with prongs to hammer or press into the wood). 8 mm bolts held the bungs firmly in place. There was a neat ring of 8 bungs on the bowl reversing jaws ready to grip almost any size of bowl.
I expected the soft rubber to give a non-marking grip and accommodate small positioning errors. But the rubber bungs were a bad idea because they had too much give. So any but the lightest cuts would move the bowl in the jaws. Therefore I turned a set of wooden pegs to replace the bungs. Another option would be to make wooden jaws, fixed to the plates and turned to give a more even grip on the bowl.
Making wooden pegs
This was an easy job. I cut a number of short sections of a moderately soft timber and drilled an 8 mm hole right through the middle of each one. I mounted them in the lathe between a conical ‘dead’ centre in the headstock and a live centre in the tailstock. The dead centre had enough friction to drive the piece. Doing it this way ensured that the holes were central in the finished pegs.
I turned the pegs all to the same size as the rubber bungs. They are 30 mm long, 30 mm wide at the top and 26 mm wide at the bottom. I could have used shorter pegs, but I had the bolts the right length for that size. I used a parting tool and calipers to set the greatest and least diameters. A sharp spindle roughing gouge cut the slight taper. I used a skew chisel to square the ends so they would sit firmly on the quadrants.
Testing the new pegs
I used them to remove a temporary chucking tenon from the base of a Robinia bowl. They held better than the rubber bungs. But bowl reversing jaws of this type never give the most reliable grip and heavy cuts cannot be taken. Tailstock support will give more security. I can foresee that wooden pegs could mark or damage a fragile rim, so care will still be needed for that reason too. I have heard of people using a rubber sleeve over a wooden core. Rubber tubing or even plastic hose pipe might work for this.