As Topic reads,was curious to know how much force a 11/8" 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?
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How Much Clamping Force does Vise Have
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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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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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Originally posted by Doozer View PostYou would need to do a vector analysis or a friction efficiency study to get even close.
D
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Or build your own pressure gauge like this person did: https://www.practicalmachinist.com/v...gvise301601/Tom  Spotsylvania, VA
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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 PostI 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
And if you look REAL close at an analog signal,
You will find that it has discrete steps.
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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 fancydancy 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 PostYou would need to do a vector analysis or a friction efficiency study to get even close.
DPaul A.
SE Texas
And if you look REAL close at an analog signal,
You will find that it has discrete steps.
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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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Originally posted by lakeside53 View PostIt'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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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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