6 Jaw Chucks

[Tony Wells]

Question, Gary. If you remove the top jaws, aren't the master jaws still in contact with the work? In my observation, a properly ground chuck has master and top jaws ground together to provide maximum length of grip.

 

[8ntsane]

Question, Gary. If you remove the top jaws, aren't the master jaws still in contact with the work? In my observation, a properly ground chuck has master and top jaws ground together to provide maximum length of grip.

On my 2-pc jaws they would be, but you could get away with it if the work piece didn't go in past the face of the chuck, I think?
I allways thought that the more surface of the jaw in contact of the work piece provides a better clamping action. I guess the biz I was in for so many yrs has me thinking this way. I relate it to race tires (Drag cars) in my case. They have no treads, as that makes spaces between them, and would reduce the contact patch area that sits on the pavement, and would effect the grip, and traction. Not to be confused with any other race tire, like rain tires.

Just another thought come to mind. When I need to machine a part that I know must not be marred up with any jaw marks, I use the soft jaws, and bore to size. These are very wide contact patch to the work piece, and grip extremely well. No groove s at all cut in them, just full contact. Gary may be right in his way of thinking, maybe I have it all bass ackwards, lol. Almost worth a call to Bison and get the story from them.

 

[Tony Wells]

I guess I wasn't thinking of NOT swallowing the work fully within the chuck. What you say is true. I think on the chucking pressure, maybe the proper way to think of it is distributed clamping force. The angles of the jaws and scroll determine the ultimate pressure, so if you don't divide it by 6, and use only 3 of the jaws, it must be concentrated on the used jaws.....hence doubling the PSI of the jaws in use. The advantage I see with 6 jaws is exactly the opposite, it distributes force X over 6 (albeit smaller) surfaces, resulting in less PSI. But on the other hand, if the contact area is less, as it could easily be, that distribution factor could be negated and the ultimate chucking force near equal.

 

[george wilson]

I'd rather use a 6 jaw when it is needed than take jaws out and get chips and metal dust into the open slots. Perhaps tape over them. The 6 jaw is still more delicate than a 3 jaw. Look how thin the metal is between those "pie slices". So I save mine for thin stuff. My favorite chuck is my Bison 4 jaw universal chuck. You can grip round or square with it. For hex, you must use the 3 jaw,or the 6 jaw.

It doesn't take much to spring a delicate chuck out of truth.

 

[GaryK]

Question, Gary. If you remove the top jaws, aren't the master jaws still in contact with the work? In my observation, a properly ground chuck has master and top jaws ground together to provide maximum length of grip.

That's true if the work extended more than 1.5" into the chuck.