This chuck spacer allows you to align 30 oz tumbler perfectly to the chuck surface.  Laser cut from plywood. Fits 3 inch (80 mm) chucks with outside jaws.

Usage is simple.

Place spacer into the chuck and secure it slightly by moving jaws inside. Now fit your 30 oz tumbler over the jaws (so they are inside tumbler) and press it against spacer so it’s flat and even. Start moving jaws outside until they hold tumbler securely.

 

Weight 1 oz
Dimensions 3 × 3 × 1 in