How much force in a vise?

How much force does a common shop vise develop in its jaws? Google was pretty unhelpful on this - the only reference I could find suggested up to 7000 lb. Another paper suggested that a minimum required clamping force for machining is much less - up to 1000 N.
I am interested because I am trying to guess how much force I can develop in this press:
http://www.flickr.com/photos/27683124@N07/5938730984/in/set-72157622484352534
Right now my answer would be "not enough" (see the following photos if you are interested in the process).
Can anybody suggest how such force could be measured?
Michael Koblic, Campbell River, BC

snipped-for-privacy@gmail.com wrote:
  Quoted Text Here  
Looks a lot like a wine press. I know the small wine press I have will develop about 1000 pounds at the plate with a 2' lever on the handle.

  Quoted Text Here  
Michael
Although not sure of the span dimension I am almost sure I could easily bend th 1/2" plate so any measurements would be questionable unless the bend of the span were taken into account.
And from many years of using presses in connection with photography I am not sure the heat requirements are at all dependent on the pressure. The pressure is probably needed to assure enough contact so the heat can do its thing for the mechanical connection of the media. The heat is probably needed to fuse the media and not completely dependent on pressure.
My two cents. Bob AZ

On Thu, 14 Jul 2011 22:37:28 -0700, Bob AZ wrote:
  Quoted Text Here  
...
  Quoted Text Here  
He used 1/4" plate, and in later picture says bending was a problem. I expect that 3/4"-1" plate probably is needed to avoid much bending.
  Quoted Text Here  
Probably so. Unfortunately, the <http://www.techniks.com/how_to.htm Press-n-Peel web page is a bit vague on requirements, merely saying "Temperature setting on the iron is critical, [...] Suggested starting temperature is 275-325 degrees F. [...] Iron until board has completely and fully reached the temperature of the iron. Time varies with the size and thickness of the board. Generally this is 1.5 to 10 min." They do offer a HIX Corporation Heat Transfer Press, on their information page.

On Jul 15, 12:13 am, snipped-for-privacy@gmail.com wrote:
  Quoted Text Here  
That's sort of like asking how fast a common car goes... Different vices have different thread pitch, different handle lengths, and different (stronger/weaker) humans operating them. So, unless an answer like "somewhere between 500 and 20,000 pounds" satisfies your curiosity, you may be disappointed.
You should be able to calculate (roughly) the force your press will generate using the thread pitch, length of the handles and how much force YOU can apply to the handles (which may be the hardest to measure)...assuming it's strong enough to hold together.

  Quoted Text Here  
The formula to find the force exerted by your screw is F= 2*Pi*r*p*f
F is the force of the screw Pi is 3.14159 r is the distance from the center to the handle p is the screw pitch f is the force you exert on the handle
from the photo, I estimate the screw multiplies your force by a factor of 75.
However, evenly applied force is not the way to remove bubbles. You will just trap them and compress them. The way to remove bubbles would be to run the plate and film between two rubber rollers with a rigidly-held, but adjustable gap. Another way is to apply the force through a slightly domed rubber pad so the center contacts first and the air is pushed to the outside. You have to make sure the rubber is compressible enough and the force is great enough that you make contact on the outer edge.

On 15/07/2011 05:13, snipped-for-privacy@gmail.com wrote:
  Quoted Text Here  
It's easy to work out. Let P = the pitch of the screw, and H = the length of the handle (this is measured at the point where you grip the handle and is generally a little less than the actual length). The mechanical advantage of the system is then 2*Pi*H/P
Assuming the pitch is, say, 0.1", and the handle is 12" long, then the mechanical advantage is 2*Pi*12/0.1 = 75.4/0.1 = 754 If you apply a force of 10Lb to the end of the handle, then the screw will exert a force of 7540 Lb, assuming no losses due to friction. Unfortunately, the frictional losses will be rather high, probably more than 50%, so the actual force would be more like 3000 Lb. IHTH

On Jul 15, 12:13 am, snipped-for-privacy@gmail.com wrote:
  Quoted Text Here  
I just checked the bench and milling vises with a hydraulic load cell, which is a cylinder of 1 sq inch area attached to a 10,000 PSI gauge. At a 'reasonable' handle force without hammering the 4" milling vise reached 1500 lbs, the 3-1/2" bench vise 2000.
jsw

On Fri, 15 Jul 2011 04:06:38 -0700 (PDT), Jim Wilkins
  Quoted Text Here  
Don't you have a 5 or 6" mechanic's shop vise, too, Jim?
I'd be willing to bet that one could do the 7k# force Mikey suggested. Wilton vises have 25kpsi castings. Another ad suggests 30kpsi. Tormach uses 80kpsi ductile iron bodies. Neither suggests jaw force.
Cool! I'd never seen an air over hyd vise before. http://www.posilock.com/Hydraulic%20Vise/Vise.htm
-- Learning to ignore things is one of the great paths to inner peace. -- Robert J. Sawyer

wrote:
  Quoted Text Here  
I did but never used it and eventually traded it for a welding table etc. I can accomplish more through subterfuge than brute force.
The 4" brake 2805-0105 shown here bends thicker stock more neatly: http://tool.wttool.com/search?w=4%22+brake&x=35&y=9
jsw

On Fri, 15 Jul 2011 06:17:09 -0700 (PDT), Jim Wilkins
  Quoted Text Here  
Age and treachery will always overcome youth and skill. (I know. I owned the t-shirt.)
  Quoted Text Here  
http://goo.gl/yEznb I have this type, plus a shorty bender from HF.
-- Learning to ignore things is one of the great paths to inner peace. -- Robert J. Sawyer

On Thu, 14 Jul 2011 21:13:28 -0700, snipped-for-privacy@gmail.com wrote:
  Quoted Text Here  
Use a trailer tougue scale or a Snap on brake force gage. I happen to have a snap-on brake force gauge set, they are only 1/2" thick and made to go in a caliper in place of the brake pads to check caliper pressure. Measure 0-5000 pounds.
http://www.sherline.com/lm.htm
Remove 333 to reply. Randy

wrote:
  Quoted Text Here  
Thank you and all the others for helpful information.
To answer some of the points that have been raised:
1) There is no question in my mind that two *heated* rollers would be the way to go. I have looked at several solutions including laminators but nothing fit the bill.
2) Up to now I have been heating the workpieces on the same 1/4" aluminum plate and then going over them with a hard rubber roller. Using a bathroom scale etc. I estimated the pressure developed this way at 21 psi. The results are reasonable with temperatures in the region of 160-170C but the bubbles are a problem as the pressure is applied *after* heating. No amount of rolling will get rid of them then. Often they are in a place where they can be re-touched but sometimes they are not and the piece is scrap.
3) The reason I do it this way after five years of experimenting is that I found the recommended method by Press-n-Peel quite useless. It works on PCBs. On anything thicker - not so much. There are others who have described successes with the Press-n-Peel iron-on method but the big question is always consistency. I did look at the Hobby Lite press from HIX but before I spent $325 I wanted to make sure that the press is suitable for what I wanted it for. The company was not particularly helpful or forthcoming with information.
4) I jury rigged a press using two clamps. There is no question that on small pieces at least I develop higher pressures this way. This has reduced the number and size of the bubbles. However, the rub is that sometimes the pressure is too much and fine detail gets obliterated (I did this today with a 7 in2 piece which I only took up to 130C - one tiny bubble but I shall have to go over the details with a needle).
5) I knocked my version of the press together from whatever I had in the house. Frankly I did not expected it to last very long. Using the two clamps was a pain and sometimes there was a clearly discernible pressure gradient across the piece. I was hoping that the central screw will provide more even pressure distribution and better pressure control. I was disappointed at its performance but in retrospect I should have expected that as the whole area under pressure is 80 in2 thus to produce the same pressure as I do manually with the roller I would have to develop over 1600 lbs force. Of course the idea was to produce more.
6) The press reminded me today that the force developed is not inconsequential as it blew one of its legs off. Still, I learned a fair bit from the effort.
7) Thanks to the gentlemen who provided me with the formula. I found it independently in the Machinery' Book late last night after I posted. I should have found it much sooner if I fed "jackscrew" into Google. Such is life :-). The figures I got was 125x multiplier without friction. I tried to do the calculations with an assumed coefficient of friction of 0.2 and got a multiplier of 31.5. Seems kind of small. I haven't the foggiest what kind of force I put on the end of the lever (3" long, BTW, the pitch is 0.151" and the pitch diameter roughly 0.6").
8) Version 002 is in the works with many changes. I am still not sure how to achieve a consistent force (it is much easier to manipulate the temperature). I wonder if a torque wrench would be the answer if somehow incorporated in the top lever.
Michael Koblic, Campbell River, BC

On Jul 15, 10:01 pm, snipped-for-privacy@gmail.com wrote: The figures I got was 125x multiplier
  Quoted Text Here  
My father tells me that anything that will not run backwards has an efficiency of less than 50%. You cannot spin the shaft on a vise by prying the jaws apart, or it would not stay clamped.
He once designed a vehicle with worm gear drive, that when the driver took his foot off the gas, the vehicle skidded to a stop.

I'm kinda' late to this discussion, but I just had an idea for a device that would excel in evenly-applied-force. That would be an air bag, fitted in a box. A reverse of the vacuum air bag, which is limited to 15 psi. I don't know how much more that 21 psi you'd want, but a bag-in-a-box could do much more than that.
For a bag, how about the bladder that's used in the storage tank for well water, or in the expansion tank of hot water heating system. The bladder itself is available as a replacement part.
Bob

Am I missing something? Is this business with the press all about getting rid of air bubbles under the sticky film? Pressing bubbles makes them smaller but they just, you know, re-expand when you stop pressing. And they migrate if you roll -- it's like spearing buttered green peas with a fork on a china plate.
Apply the film as well as you can. Maybe make an initial pass with a roller or iron to get it well stuck down.
Locate any bubbles. Use a fine hypodermic needle to pierce the film and release the bubble, gently rolling the film down with a narrow steel roller as you do so.
Then use your iron or press or whatever to do the iron-on step and finish the heat transfer.
There used to be a product used by newspapers to produce cylindrical rotogravure plates, called IIRC "carbon film". I tried to get some 30 years ago and no one around here (very far from the NYT or the Chicago Trib :-) had ever heard of it. So I suppose it's no longer made or is hiding in some industrial niche somewhere. I wanted it to do stuff very like what you're trying to do.
force of a screw was:
force(out) = 2 Pi force(on handle) length-of-handle screw-pitch
which is apparently wrong!
Wikipedia says:
force(out) = 2 Pi force(on handle) length-of-handle --------------------------------------- screw-pitch
which agrees with Machinery's Handbook (P. 309 in 17th ed, 1972).
By that reckoning my cider press [1](which is a whole lot sturdier than the OP's press [2]) develops ca. 30,000 pounds (or ca. half that, if there's a 50% friction loss.)
- Mike
[1] http://home.tallships.ca/mspencer/temp/cider-press.html
Ca. 2" Acme screw has a pitch of 0.42". "Handle" is ca. 40" and I'm guessing I put 50# on it as the pomace gets pressed down real hard.
[2] http://www.flickr.com/photos/27683124@N07/5938730984/in/set-72157622484352534

wrote that the axial
  Quoted Text Here  
You would use my formula if the screw pitch is in threads per inch. Use the one in the machinery handbook if pitch is given as distance between threads. There also would be more than 50% loss due to friction.
I agree with what you say about bubbles. Evenly applied force will not work. Someone else suggested a vacuum bag which might also work.

On 16 Jul 2011 17:52:03 -0300, Mike Spencer
  Quoted Text Here  
Actually they don't. Even if they did it would not matter because by that time the resist is transferred to the workpiece.
  Quoted Text Here  
I wish they did. They don't, which is the point of the whole exercise.
  Quoted Text Here  
I haven't tried poking them. Good idea! Trouble is sometimes they are not visible until you remove the backing. I have found that preventing them is the way to go.
  Quoted Text Here  
I used to do this with ordinary transparencies but they do not work as well as Press-n-Peel.
[...]
Michael Koblic, Campbell River, BC

On Jul 16, 1:01 am, snipped-for-privacy@gmail.com wrote:
  Quoted Text Here  
I think up to ~80% of the tightening force on a screw can be lost to friction. Compare the torque to tighten with that to loosen.
jsw

On Sat, 16 Jul 2011 15:24:04 -0700 (PDT), Jim Wilkins
  Quoted Text Here  
I guess they are different :-) ??
I re-did the calculations using the 2 formulae in the Machinery's Handbook: One for when the motion is in direction of the load (assisting it) and the other in the opposite direction (opposing).
With the same data I got the force necessary to move a load of 1000 lb to be 6.66 lb in the first case and 9.68 lb in the second case. This time the multiplier is 103 and 150. GOK where that 31.5 came from. The multiplier without friction is smack in the middle. That makes sense, does it not?
Michael Koblic, Campbell River, BC