Lathe – workholding – cross drilling attachment
This device is designed to be used on the lathe so the user can cross drill a round part.
The attachment is fitted in the tailstock.
fig cross drilling jig fitted to the tailstock of the lathe
A center drill is fitted in the three jaw chuck mounted in the headstock. If the chuck is not accurate it would be possible to:
hold the center drill in a collet chuck
hold the center drill in a ER collect chuck held in a four jaw chuck.
The workpiece is fitted in the groove in the cross drilling jig.
fig workpiece held in the cross drilling jig
It is much easier if the cross drilling jig has a clamp(s) on it to hold the workpiece. If the workpiece should rotate at all between the center drilling and the final drilling then the final hole could well not be truly crossed drilled.
With the center drill rotating, the tailstock barrel is driven forwards so that a center is drilled in the workpiece.
The center drill is replaced with the required drill and the workpiece is drilled.
It will not be possible to drill a round surface without center drilling it first.