About the 1/2″ and 5/8″ shank to 3/4-16 chuck adapters
When using a large mill or lathe with 5C, ER or other large collets it is sometimes helpful to have a way to change to a small chuck quickly. These adapters have either a 1/2″ shank (10660) or a 5/8″ shank (10650). On the other end is a 3/4-16 thread that accepts any Sherline 2.5″ or 3.1″ chuck. This allows you, without changing your spindle or going to another machine, to quickly install a Sherline 3- or 4-jaw chuck. Just insert the shank of the adapter attached into a 1/2″ or 5/8″ collet. Now you can chuck up parts that could not be easily held in a collet. T.I.R. of the adapter is specified to be 0.0005″ (0.013mm) or less. The unhardened steel adapters have a black oxide finish to prevent rust.