SuperNova Chuck jaws

[Johnm Chase]

I was looking recently for a set of basic jaws in the 75mm range it seems Teknatool has dropped them instead selling the 75mm bowl jaws as a replacement.
I would use them for spindle work anyone have any thoughts on this?

[Gary Garmar]

John, right now Ebay has a listing for 75mm step jaws for Nova chucks. I think the cost is less than $50.

[Mike Peace]

Can you describe how you plan to use the 75 mm jaws for spindle work? I guess I am having difficulty understanding what the larger jaws will do for you for spindle work.

The standard #2 jaws usually meet my needs for larger spindle work like turning 3" fruit or tops when turning between centers won't work and I need to use a chuck. I have several sets of the Nova jaws including the Powergrip jaws but not the 75mm. If you are looking at jaws for large diameter end grain pieces you may want to consider the powergrip jaws. I always put a tenon on the piece I am turning while I am roughing it betwen centers to insure the best grip.

[Johnm Chase]

What I am doing is turning a 3x3x12 inch ...at the point where the wood is rounded over the blank is a bit large for the 50 mm and too small for the 100mm closed down. I would like to be able to turn the stock for the mill at a size larger then the2 inches required to fit the 50 mm max opening. The 75mm
would have worked but the only available 75 now is the bowl set. I am not experienced enough to come up with a better solution. The salesman at woodcraft said he uses bowl jaws for his spindles, the only reason I am looking at this is lack of knowledge, the bowl jaws seem a bit aggressive.

[Mike Peace]

Now I understand. Chucking technique is not as an experienced turner once commented, "intuitively obvious to the casual observer."

Rather than get jaws to fit your cylinder, simply use your parting tool to make a slight tenon to fit your jaws. It only needs to be about a 1/4 to about 3/8" long. Do not make the tenon too long as the end of the tenon must not bottom out inside the chuck. Do not simply have the jaws grab the outside of the cylinder which will not hold the piece without the tail stock being used! The strength of the correct tenon hold comes from the face of the jaws resting against the face of the tenon shoulder as well as the grip of the jaws against the tenon. The shoulder of the tenon needs to be flat so that you cannot slip a piece of paper between the jaws and the face of the tenon.

The importance of correct chucking a tenon will become obvious when you start bowl turning. Doing it wron can hurt you!

Hope this helps. If not clear, you may want to refer to a good basic turning reference book like Crowley's Woodturning: a Foundation Course. Good luck with your turning.

[Mike Peace]

Actually the book is by Rowley not Crowley and although it covers a lot of basics, it is not strong on chucking with a 4 jaw chuck. You may want to look at the following thread for some excellent discussion on making a tenon.
http://sawmillcreek.org/showthread.php?t=65848&highlight=chuck+tenon

Note that you cannot safely turn a 3X3X12 unsupported by the tailstock with the 50 MM jaws per the SN2 manual:


"With the standard set of 50mm jaws a maximum size wood blank of 100mm (4 inches) diameter (NOT spigot size) by 150mm (6 inches) length can be turned. Square timber of same length and between 40mm (1.5 inches) to 50mm and grip all four jaws into wood. MAKE SURE YOU HAVE AN ADEQUATE GRIP BEFORE OPERATION by vigorously wrenching the limb mounted on chuck. If any loosening occurs DO NOT PROCEED with operation. Repeat tightening procedure and retest grip."