Introduction: Doughnut Chuck
A Doughnut Chuck is a great jig to hold turned bowls on a lathe. It grants access to flatten and finish the bottom of any bowl. This simple chuck can be made in an afternoon and can be customized to fit any lathe and bowl.
Step 1: Tools and Materials
Step 2: Hardwood Tennon
Step 3: Turn Tenon
Turn the block round and create a tenon on one end (if using a face plate just turn flat). Remove from the centers and mount in the chuck. Turn the face of the block flat. Verify with a straight edge.
Step 4: Cut Circles
My lathe has 6 inches of clearance between the headstock and the bed. Because of this, I cut the radius of my circles a half an inch shorter to ensure that the two disks spun clear of the bed. Cut out the circles with a bandsaw or jig saw.
Step 5: Glue and Turn Circles
I used regular wood glue to attach the circles to the hardwood. Use the tailstock of the lathe to clamp the circles in place. Once the glue is dry, turn the circles round.
Step 6: Drill Holes
Mark a line around the face of the disc a half inch in from the edge. Drill four 1/4 inch holes around the edge along the line previously marked.
Step 7: Insert T-Nuts
Drill a hole from the back side the size of the t-nut. Tap the t-nut in place. Mark index numbers on the face plate.
Step 8: Mark and Part Inner Ring
Measure the size of bowl you want to hold in the chuck. My bowl needed a chuck with a 7 inch diameter hole. Mark the hole and use a parting tool to remove the circle.
Step 9: Install Foam Lining
Multiply the inner diameter of the ring with pi (3.14). This will give you the needed circumference of the foam lining. Add two inches because the foam will compress and cut to length. Open the split side and place it over the inner circle. This will give padding when holding the bowls in place.
Step 10: Finish the Bottom of the Bowl
Attach the loose ring with bolts and washers. To place a bowl in the doughnut chuck, loosen all bolts (removing one) and slide a bowl in from the side. Tighten all bolts equally (I use a socket in my drill for quick changes). Now go flatten and finish the bottom of any bowl.