Nova Compact Chuck Question

Keith, be sure to make your tenons or dovetails short enough so the jaw faces register against the workpiece. Make tenons/dovetails of a circumference that the jaws form a circle. _Don't over tighten excessively---you are holding and driving---not wringing or cutting notches. _Do recheck tightness shortly after beginning or after a long rest. Arch

Fortiter,

Don't think grip, think wedge. I don't own a Compac, but the jaws on my Nova have a dovetail in and dovetail out feature. If you're holding a tenon, your objective is to get the inside wedge to draw the piece tight against the face of the jaws. Prepare the piece with a tenon about a quarter of an inch greater than the minimum inside diameter of the jaws, and a 1/4" or so greater diameter surface for the face of the jaws to bear against. This may be _mildly_ undercut to ensure proper mating, but in any case should have no torn pieces of grain or dust to interfere with flat to flat mating surfaces. I take the nose of a skew and sever the fibers mildly at the junction of the small and large, to make it easier for the wedge to push them below, rather than just compress them. The tenon should not bottom on the base of the jaws. Trying to get it to do so will often deny you the better grip and greater leverage gained by the nose bearing against the flat surface on the piece. other than that, a quarter inch or longer should hold almost anything, with green wanting a bit more.

I have a Compac chuck. I find that it holds better in the expansion mode. Cut your recess about 1/4" deep with a dovetail shape that matches the angle and diameter of the jaws.

Barry

Thanks everybody for the advice. Just got back from the country. Will try your suggestions!