How to Use a Chuck Adapter Plate

Locate the square adjustment nuts on the lathe spindle. The spindle is the round object that the lathe chuck attaches to on your engine lathe. The square adjustment nuts on the spindle look just like the square adjustment nuts in which you place the lathe’s chuck key to open and close the jaws on the chuck.

Support the front of the chuck with one hand and loosen the square adjustment nuts on the spindle with the lathe’s chuck key. Pull the chuck out of the spindle.

Slide the spindle adapter into the hole and tighten the nuts just tight enough to hold the adapter in place.

Position a dial indicator on the lathe’s carriage and place the needle of the indicator against the face of the adapter plate. Move the dial on the indicator until the needle lines up at zero.

Rotate the spindle. As you do this, the dial on the indicator will move up and down. Stop rotating the spindle when you get to the lowest negative number. Tap the opposite end of the adapter plate with a rubber mallet to move the adapter slightly. Keep rotating the spindle and making adjustments until the face of the spindle runs true. You know the spindle runs true when the dial stays on zero for a full rotation.

Tighten the square adjustment nuts on the lathe spindle with the key chuck.

Place the specialty spindle onto the face of the adapter place and thread the fastener bolts through the back of the adapter plate and into the chuck. Tighten the bolts with the appropriate sized Allen wrench.