These chucks are designated “0JT” which stands for “Zero Jacobs Taper,” because it comes with a #0 Jacobs tapered hole in the back. Into that, we have pressed a special arbor that provides a #1 Morse taper to fit into the Sherline headstock. A chuck key plus a drawbolt and washer are included to secure the chuck in position.
These chucks are useful for holding very small drills and their shorter length provides an increase of about 1/2″ in working space between centers compared to the 1/4″ drill chuck.
Runout, as specified by the manufacturer, is .004″ or less but we try to maintain .003″ or less in our testing process. If runout of less than .003″ amount is required, collets should be used to hold the drill rather than a chuck.
NOTE: Because the arbor is pressed into the chuck, it is not interchangeable from chuck to chuck. A separate chuck must be purchased for #0 and #1 Morse use.