Salmac,
I am interested in understanding how to properly press cheese. I am reading your post, and you indicate you are applying 40lbs of pressure.
I see two water bottles on top of your cheese.
Assuming these are at most 2 gallon jugs, this will yield 4X8lbs=32lbs of wieght.
Now, if you divide that by the surface area of your cheese, you will get your pressure that is actually being applied to your cheese.
So, assuming a 4 inch wheel, and 32lbs of weight, this gives you about 2.5PSI
If you were going to make a 6 inch wheel, or a 10 inch wheel, would you increase your wieght to maintain the 2.5PSI?
Do other folks care about PSI?