8" Bison 4 Jaw Combination Chuck

[ddickey]

What's MKSJ?

 

[Dave Paine]

What's MKSJ?

Not a "what", rather a "who", forum member name is MKSJ.

 

[Alan H.]

What's MKSJ?

That would be Mark, the builder of many of the variable speed control systems on the PM1340GT lathes, mine included. He is a an electrical controls wizard plus he knows a lot about this hobby of ours!

EDIT: should have said that he's also built controls for lots of other lathes, mills, and machine tools in addition to the PM1340's.

 

[Alan H.]

Mark and Paco, how do you gents handle this little chuck? It is a bit heavy isn't it? Did you build a sled to help mount it or do you simply mule it on there?

 

[mksj]

Most of the time, two hands, preferably dry, not too old yet that I can't pick it up and get it in place. I have a padded insert block that locks in position on top of the ways, I use it whenever I am changing chucks. Just for safety, as the chucks can slip. I mark my chucks so they always go in in the same position, I have the key in the top cam-lock, so I hold the chuck in place with one hand and lock one pin with the other. David Best made a very nice chuck holding sled that fits on his ways, probably a better way to go.

 

[Alan H.]

Chuck keys for independent jaws are made from 3/4" drill rod and are 1.85" in overall length. The T bar is 7" and held in with a set screw, the back is drilled to make them lighter. The key tip has a small Neodymium magnet that holds it in the chuck so you can rotate the chuck and not have the keys fall out.
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Mark, what diameter is the T bar - 1/4"?

 

[Firestopper]

I do the same as Mark. I took a piece of 3/4" plywood, cut it to cover the ways and brad nailed to rail strips that index snugly to the inside portion of the bed ways. It also can double as a platform for tooling when used behind the tail stock. The Bison is hefty, but not that bad for me yet. I like what David Best shared sometime back for his solution as well. I should do the same before long.
I also index all my chucks to the spindle (center punch).
David Best's solution is the "best"

 

[mksj]

Mark, what diameter is the T bar - 1/4"?

Yes, 1/4" drill rod. Balance of weight and strength on the T bar. David's chuck carriers are the slickest, but I am already space limited, and I would need a place for the chuck carriers.

 

[wildo]

I just bought an 8” Bison 4 Jaw Combination chuck for use on my PM1340GT.

OK- am I being dense here?? What is a "combination" chuck when it relates to a 4 jaw? I have a Bison 3 jaw 6" adjust true chuck, which is what I think of when I think of a combo chuck. The "adjust true" part of it is basically a built in 4 jaw for centering the 3 jaw. But on a 4 jaw chuck... what is the combination? Sorry if that's an obvious question...

 

[Alan H.]

I have been using a board to protect the ways when changing chucks. I can "mule" this new one on there but it weighs enough that I decided I did want a sled to make it easier. Made one last night out of maple, sealed it with spar varnish, and it works fine, although it is not to David's standards!