The Shopsmith Lathe Drive Center attaches directly to the spindle of any MARK model for simple, secure turning support. Use a mallet to drive the four steel spurs of the drive center into the center point of your turning stock and attach to the MARK spindle with the included set screw. Lathe Drive center is made of steel with a replaceable Center Pin. 1 Inch OD and a 5/8 Inch ID x 1-1/2 Inches long. Attaches to the Shopsmith Quill spindle with a single 5/16-18 set screw.