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How Much Clamping Force does Vise Have

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  • How Much Clamping Force does Vise Have

    As Topic reads,was curious to know how much force a 1-1/8" x 5tpi Acme thread on Shaper Vise would put out.Threads are lubed and it has Endthrust Ballbearing with 10" long wrench tightening with 80lbs preasure?

  • #2
    In the age of video hustles Fireball has over an hour on that subject beginning with
    https://www.youtube.com/watch?v=VcbTopj5u7A

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    • #3
      I would think the maximum theoretical mechanical advantage would be one turn of 10" x PI = 31.4" / 0.2" lead per turn, or 157:1, so 80 pounds would be a force of 12560 pounds. Practically, I would expect somewhere between 1/2 and 3/4 that force. About four tons.
      http://pauleschoen.com/pix/PM08_P76_P54.png
      Paul , P S Technology, Inc. and MrTibbs
      USA Maryland 21030

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      • #4
        How many angels are dancing on your head
        would be an easier question to answer accurately.

        -Doozer
        DZER

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        • #5


          Franz: Thanks he burned up a lot of Vises!

          Paul: Thanks I knew some of you math Wizards would have a answer!

          Doozer: No Angels that I know of, I knew some Math Guru's could calculate it with data included.

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          • #6
            You would need to do a vector analysis or a friction efficiency study to get even close.

            -D
            DZER

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            • #7
              Originally posted by Doozer View Post
              You would need to do a vector analysis or a friction efficiency study to get even close.

              -D
              I not capable of doing ether one of those studies lol,I did note about lubed threads as Kello-Bilt Feild Discs have 2 torque specs for main gang shafts Dry&Lubed and they are substantially different.

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              • #8
                Or build your own pressure gauge like this person did: https://www.practicalmachinist.com/v...g-vise-301601/
                Tom - Spotsylvania, VA

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                • #9
                  About what I would have said/done. But there are problems with a mathematical approach.

                  One: There is no way that a 10" wrench will equate to an actual 10" lever arm. You need to subtract an inch or two from that because your hand has to grip it at a place that is somewhat short of the full length. So there goes another 10 or 20 percent.

                  And, as others have mentioned, the friction will depend on the actual screw, the actual thrust bearing, other sources of friction in the vise, and the actual lubricant used. That's Paul's 1/2 to 3/4s factor and I would tend to use the low end of that range if not even less.

                  The fact is, the math is only a poor way to predict the actual force that can be applied by a vise.



                  Originally posted by PStechPaul View Post
                  I would think the maximum theoretical mechanical advantage would be one turn of 10" x PI = 31.4" / 0.2" lead per turn, or 157:1, so 80 pounds would be a force of 12560 pounds. Practically, I would expect somewhere between 1/2 and 3/4 that force. About four tons.
                  Paul A.
                  SE Texas

                  Make it fit.
                  You can't win and there is a penalty for trying!

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                  • #10
                    Friction study? Well, yes but it needs to be done on that particular vise. You may as well just measure the force directly.

                    As for a fancy-dancy term like vector analysis, I do believe that Paul's math is essentially that. It includes all the pertinent vectors. But his math avoids any reference to vectors by simply using the ratio of the two distances that are traveled. It is perfectly precise if all friction is eliminated from the situation and if the actual EFFECTIVE length of the wrench is used. It is the friction that is the real bitch here as it is almost impossible to predict and a lot easier to just measure.



                    Originally posted by Doozer View Post
                    You would need to do a vector analysis or a friction efficiency study to get even close.

                    -D
                    Paul A.
                    SE Texas

                    Make it fit.
                    You can't win and there is a penalty for trying!

                    Comment


                    • #11
                      It's easier to simply measure than deal with unknowns. Just put a short hydraulic cylinder (like a 2" high 5T Enerpac 10,000psi cylinder or whatever) in the vise, install T with a pressure gauge, charge with fluid and bleed. Crank away. You know the surface area of the ram and the pressure developed. Easy calc.

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                      • #12
                        Thanks Guys,I realize there's a lot of variables but was just curious of ball park # as I attempted to pry up on peice to remove out of Step Jaws with 4' pry bar
                        it never budged.

                        Paul did you see the results on Jaw lift in other post?

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                        • #13
                          Originally posted by lakeside53 View Post
                          It's easier to simply measure than deal with unknowns. Just put a short hydraulic cylinder (like a 2" high 5T Enerpac 10,000psi cylinder or whatever) in the vise, install T with a pressure gauge, charge with fluid and bleed. Crank away. You know the surface area of the ram and the pressure developed. Easy calc.
                          NO, absolutely not. You MUST build a hydraulic trailer tongue scale like minimally 1000 other Inturdnet people.

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                          • #14
                            if you could get half the theoretical clamp load, it would loosen on its own.

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                            • #15
                              We will see if PStechPaul gets a Blue Ribbon for his calculations.Was talking to the Truck Scale Co. we deal with and he has a Certified electronic load cell with digital read out that I will get.I always wanted to check my Arbor Presses to see if rating were close,so will test every thing in the shop including Vises lol!

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