Independent 4 jaw lathe chuck, with the jaws independently set. The key is used to adjust each jaw separately. An older and larger 4 jaw chuck.
A 4-jaw chuck is a great, almost essential, accessory for any serious lathe worker. While it lacks the self-centering convenience of the the 3-jaw chuck, it has other capabilities. Some things you can do with the 4-jaw are…
Grip rectangular and other non-cylindrical shapes for turning or facing
Moreover it forms rectangular shaped objects
Also Precisely center cylindrical stock to within the limits of the lathe’s accuracy
Hold stock off-center for turning cams or drilling off-center holes
Independent 4 jaws lathe chuck have each jaw mounted on a thread spindle allowing independent adjustment.