Longworth Offset Experiment

[Joe Greiner]

I moved two of the buttons on my Longworth chuck to neighboring slot intersections. This had the effect of relocating the center of the workpiece offset from the lathe axis, for turning an added feature. If the added feature were simply a round pocket of an exact size, a Forstner bit would be more effective. But for anything else, it works great, subject to limited variability.

I think a similar modification could be made to Cole jaws.

And in either case, the modification can be un-done to restore normal function.

(One of the faceplate screws was mis-aligned amd didn't pierce the front face. The sloppy initial rim was a product of haste.)

 

[MichaelMouse]

Takes a delicate hand, I'll bet. Those buttons slip pretty easily. How about Darrell Feltmate's old trick of using different diameter jaws (e.g. 2" and 4" on your Nova Chuck? I've done it on tenons, and it felt more stable than standard Cole jaw work.

Another alternative is to use the disappearing hold method used on round-bottom work, where a ring of material is left to hold the turning, then pared and sanded away. Might combine and use the offset buttons for final trim instead.

 

[Joe Greiner]

The buttons on my Longworth cinch down fairly tight. Holds dimension well.

As luck would have it, the jaws on my Grizzly clone of Vicmarc don't all have the same thickness at the base. Need shims on the thinner base.

I don't have Cole jaws (yet), but they probably provide maximum variation, because of all the possible button locations. And simple enough to make new locations or odd-shaped buttons. Strictly speaking, we only need 4 buttons to secure the work.