Found this;

"Pressure from a Screw Press.- The pressure exerted by a screw press is dependant on the length of the lever attached to the screw, the pitch of the screw, and the force applied on the lever.

Thus,

circumference of swing X number of threads per inch X force = force or pressure exerted by the press.

Example,

A force of 100lb. acting on a lever 20in. long which is attached to a screw having a pitch 1/2in. exerts a pressure as follows:

3-1/7 X 20 X 2 X 100 = 12,560lb., or approximately 5-1/2 tons. "

 

So the challenge is on; those who have fly presses with catalog force ratings, compare this with the calculated version.

[i'm piking out, two presses with no details]

 

enjoy,

AndrewOC

 

I think your formula is wrong:

 

The length of your lever is 20" not 3.14 of a 20" radius.

 

I don't know the proper calculation but logic would dictate that it should be more like ( pounds of force ) / (Pi x dia of screw x TPI ) or something like that and of course the subtraction of some sort of energy coefficient plus you'd have to consider the speed of ram travel also.

 

I'm not trying to be a PITA but just pointing out that your formula seems WAY to simple. 

Where is the inertia factor?

Thomas your correct. The inertia factor would probably be calculated in with energy coefficient and the speed of ram travel.