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Does anyone have a Bison 5" 6-Jaw chuck?

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  • Does anyone have a Bison 5" 6-Jaw chuck?

    Hi All!

    I was just about to order up a new Bison Set-Tru 5" (125mm) 6-jaw (2-piece) chuck for my Maximat V10P.... but I just discovered a very strange problem with this chuck in Bison's tech specs: You cannot chuck up a part that is between 43 and 50mm nor between 87 and 94mm with inside jaws.... Nor between 70 and 76mm with reversed jaws. Notice the gaps between D1, D2 and D3... and D4-D5. The jaw steps don't overlap. Their 6" (160mm) has a similar, but less severe problem (no dice between 64 and 67mm) -- and all larger chucks overlap just fine.

    The solid-jaw version isn't much better. Buck's solid jaw 5" 6-jaw doesn't have this problem.... but they're made in Asia now... (and Kalamazoo has no 5").... [Addendum: My issue with Buck's move offshore is more about feeling sore for the gutting of North American manufacturing and the destruction of huge swaths of its economy -- not racism. Bison has always been Polish so, fair game.]




    I'm disappointed; I thought I found a good solution for the broad range of work I do.

    Does anyone run a 5" Bison 6-jaw? Have you noticed this? Do you chuck 44 or 88mm parts anyway without problems?

    Thanks!
    Last edited by Teledar; 06-12-2015, 01:08 AM.

  • #2
    Do you need to turn thin wall parts?

    Lots of people seem to think a 6 jaw chuck is a superior version of a 3 jaw chuck, but it is not. 6 jaw chuck isn't as good at gripping irregular objects as a 3 jaw, so if you are trying to turn solid stock of imprecise dimensions it can cause problems.

    But they look awesome!

    Comment


    • #3
      Originally posted by tmarks11 View Post
      Do you need to turn thin wall parts?

      Lots of people seem to think a 6 jaw chuck is a superior version of a 3 jaw chuck, but it is not. 6 jaw chuck isn't as good at gripping irregular objects as a 3 jaw, so if you are trying to turn solid stock of imprecise dimensions it can cause problems.

      But they look awesome!
      Thin wall parts? Sure, I want the capability. It's more about part marring -- and as an alternative to a collet system.... an alternative to making an ER32 through-bore collet chuck. And they look awesome.

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      • #4
        I turn a lot of brass and aluminum and find that my 6 jaw leaves far fewer marks on the work than my 3 jaw chucks even when clamped down pretty tightly. I find it lot easier than messing with brass shims. My 6 jaw is a Pratt-Burnerd and I haven't noticed any 'gaps' in the clamping range (other than the fact that it doesn't close all the way down like a 3 jaw) but for anything that small, I'll either use a collet or my Jacobs headstock chuck.

        Comment


        • #5
          Originally posted by Teledar View Post
          Hi All!

          I was just about to order up a new Bison Set-Tru 5" (125mm) 6-jaw (2-piece) chuck for my Maximat V10P.... but I just discovered a very strange problem with this chuck in Bison's tech specs: You cannot chuck up a part that is between 43 and 50mm nor between 87 and 94mm with inside jaws.... Nor between 70 and 76mm with reversed jaws. Notice the gaps between D1, D2 and D3... and D4-D5. The jaw steps don't overlap. Their 6" (160mm) has a similar, but less severe problem (no dice between 64 and 67mm) -- and all larger chucks overlap just fine.

          The solid-jaw version isn't much better. Buck's solid jaw 5" 6-jaw doesn't have this problem.... but they're made in Asia now... (and Kalamazoo has no 5")....




          I'm disappointed; I thought I found a good solution for the broad range of work I do.

          Does anyone run a 5" Bison 6-jaw? Have you noticed this? Do you chuck 44 or 88mm parts anyway without problems?

          Thanks!
          Many thanks - that post regarding the "gaps" in jaw-gripping diameters - was a real "eye-opener for me as I've never come across it before.

          Comment


          • #6
            Same here, I have never had a grip problem with my 6 jaw. Yes, for uneven work a 3 jaw may have better contact, you cant not have all three jaws on the work. With a 6 it is possible to only have two. But that has also allowed me to use my 6 as a two jaw on a couple occasions.

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            • #7
              I use 6 jaw chucks almost exclusively now, except when using a 4 jaw. The 4 and 6 jaws grip tighter than a 3 jaw because there is solid steel exactly opposite each jaw. On a 3 jaw there is air opposite each jaw. I have a 6" and an 8", both are set-true style Bison chucks used on a 14" lathe with D1-4 spindle. I used them on a 12" lathe before that. Even the Chinese chucks run true with the set-true backplate. Once you put in the part you're working on and dial it in, it will repeat back to that spot very accurately.

              The great thing about the 6 jaws is you can reconfigure them to do special purpose jobs by removing jaws. I have made mine a 5 jaw for turning parts with a piece sticking out sideways. I have made it a 4 jaw for parts with something sticking out both sides. I have made it a 3 jaw on rare occasions when that was needed. I have used it as a 2 jaw a couple of times.
              Kansas City area

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              • #8
                The jaws open and close. I can't see any diameters that it would not work on.

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                • #9
                  Originally posted by ahidley View Post
                  The jaws open and close. I can't see any diameters that it would not work on.
                  There is a "gap" when you swap from inside to outside jaws... JR

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                  • #10
                    Originally posted by ahidley View Post
                    The jaws open and close. I can't see any diameters that it would not work on.
                    I'm not sure what you see.

                    With 2-piece jaws:

                    D1 will hold up to 43mm. D2 will hold down to 50mm. That's a 7mm gap that won't hold.

                    D2 will hold up to 87mm. D3 will hold down to 94mm. That's a 7mm gap that won't hold.

                    D4 will hold up to 70mm. D5 will hold down to 76mm. That's a 6mm gap.

                    That's what it says.

                    You have a 44mm solid part and an 88mm solid part... How do you hold them?

                    All chucks larger than 6" overlap just fine.
                    Last edited by Teledar; 06-12-2015, 09:27 PM.

                    Comment


                    • #11
                      I have a Bison 8" 6 jaw set-tru and I love it. I've never found anything (yet) that I couldn't mount in it other than anything smaller than 5/16" in dia. I think.
                      I've never reversed the jaws. but find it hard to believe that there is an overlap.

                      JL.............

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                      • #12
                        It's too bad no one seems to have this chuck and could make some measurements. Keep in mind Teledar, this is just the manufacturer's "opinion" and their opinion is colored by the litigious society we live in and their desire not to be sued. For example d1 is listed as a maximum of 43mm, but that's just their opinion of the maximum safe outward position of the jaws. I have used chucks with the jaws pretty far out there to grip something large, admittedly just because I was too lazy to reverse the jaws. So my opinion of what is "safe" is most likely different from Bison's opinion. And your opinion of "safe" is likely different from Bison's and mine! Perhaps you should purchase the chuck making sure you can return it if you're unhappy. You may find there is no gap based on your opinion of "safe".

                        Ed P

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