Cheese Press

I am right now working on building a cheese press. But there is one important matter I do not know how to calculate.

This is a beam style press, relying on the leverage of a large wooden beam to achieve pressing pressure. The beam is fixed at one end, and the other end moves freely up and down. You press the cheese by placing a block under the beam and bringing it down to put pressure on the cheese in the mold.

What I need to know is how to calculate the actual poundage placed on the cheese based on the leverage of the beam. For this particular cheese I need to attain 1500 pounds of pressure.

Ignoring the weight of the mechanisms, the mechanical advantage is simply the ratio of the distances from the fulcrum to the load and from the fulcrum to the force. So if the press (the load) is 3 feet from the fixed end (the fulcrum), and the lever (the force) is 15 feet long, you'll get a 5:1 advantage. So you'll need to apply 300 pounds of force to get 1500 pounds of pressure.

Yes, the simple mechanical advantage I understand. But what I need to know is if yoou have a large wooden beam, how do you factor the weight of that beam.

I have a hickory beam that will have 9 feet of working length, and the weight of that working portion is about 220 pounds

considering it a class 2 lever, how do you factor that 20 pounds? because it cannot all accurately be considered a force applied on the far end.

Do you have to be that precise? I suppose you are looking at cantilevered beam with evenly distributed load (2.037 lbs/in) formulas or something similar.

I don't really like math that is that involved at this point in my life, so here's what I would do: stick a scale where the cheese goes and let the beam rest on it and see what the dead load is.

It is not really a cantilevered beam.

Here is the design as I have it figured:

At one end there is a support structure with an H shape, one end of the beam is placed under the cross member of this H, which is about 4 feet above the pressing table. A block can be placed under the beam to hold this end up to make positioning the cheese mold easier. The other end of the beam is completely free to move up and down. Again, a block is placed under it to hold it up until you are ready to let it come down.

A wooden block is placed under the beam about 1 1/2 feet from the secured end (a little less) that is long enough to press against the cheese in the form.

Now the beam itself has 220 pounds of dead weight bearing down with some degree of mechanical advantage. I want to know how that transfers into the pressing block so I know how much additional weight I need to add to the end.

I would try the scales approach, but I do not have one that would not be destroyed by the weight of the press.

Also, I am not asking for you to figure out how much weight, I just need to know how to figure it out.

Does this help?

http://www.engineersedge.com/calculators/levers/page_levers_1.htm

http://science.howstuffworks.com/lever-info.htm

I think for a lever calculation, you can just treat the weight as a point load at the midpoint. 133lbs?

not mine, but a small one.

a bit bigger:

The trickiest piece of information you need is the load on the beam. Once you have this the process is easy.

You now the load on the beam, you will know or can decide/make up the dimensions of the beam as a lever. From that you can calculate the force transmitted to the top of the cheese. Then you just divide the force by the area that it is being transmitted to.

Does that make sense? If not I'll explain better at length.

Missed all the other replies I thought that you posted on the 2nd of august rather than the 8th of feb.

To work out the effect of the weight of the beam the suggestion of calculating from the midpoint of the beam from the fulcrum is the way to go. The other way is to break the beam up into sections and calculate the effect of the weight of each section. The further from the fulcrum the greater the effect. The closer obviously the less the effect but when you add them all you will find that it is the same as working it out from the mid point.

As I said in my first post the weight and lever calcs will give you the force transmitted to the top of the cheese stack. To work out the pressure you need to decide on the shape of the cheese stack. The wider and flatter the stack the less pressure but the more stable the stack. The narrower the stack the greater the pressure but the more care that has to be undertaken in preparing the stack because it is less stable.

How would you be preparing the stack? Will you be using a press basket? Or will you be making up cheeses in cheese cloths stacked one upon the other?