CheeseForum.org » Forum

Here's a question:

1.  With one cheese and a 2.25" diameter mold I need 25lbs of weight to get almost 10psi on the cheese (for cheddar) however I'm unsure if pressing two small molds at once requires greater weight?

2.  According to my calculations I would need  almost 100lbs to get just over 10psi on the two molds if you combine the diameters of both molds.  So, if pressing two cheeses at once do you need to increase the weight or because the press equally distributes the load onto both molds does it remain high because it's two separate molds?

I think I have the answer -- instead of spreading the load I'll stack one cheese mold on a board (oak) and stack that above the other with a wide plunger.  This will transmit the pressure through the first cheese down into the second....like the way they do it in cheese factories only theirs are horizontal and hydraulic...I think this will work though

Your applying the same amount of force to a larger area so the pressure will decrease.

If you have 2 molds side by side under 1 weight you will need twice the weight to get the same pressure. I f you stack the molds the pressure on the bottom mold and top mold is the same except the bottom mold has the small additional weight of the cheese on top of it.

Quote from: smolt1 on March 20, 2011, 12:19:46 AM
If you have 2 molds side by side under 1 weight you will need twice the weight to get the same pressure. I f you stack the molds the pressure on the bottom mold and top mold is the same except the bottom mold has the small additional weight of the cheese on top of it.

This I expected actually and will have a slightly larger mold on the bottom.

One thing about pressing two side by side -- I needed 4 times the weight to get the same PSI on the cheese!

I;m trying to figure where you got the 4 times the weight from, because if you lay a board across 2 scales side by side and put 50 lbs on the board mid way between the 2 scales you should read 25 lb on each scale. So to get 25 lbs on each mold you need 50 lbs which is 2 times.

Quote from: smolt1 on March 20, 2011, 04:24:31 AM
I;m trying to figure where you got the 4 times the weight from, because if you lay a board across 2 scales side by side and put 50 lbs on the board mid way between the 2 scales you should read 25 lb on each scale. So to get 25 lbs on each mold you need 50 lbs which is 2 times.

I'm working with PSI and trying to get 10PSI on the cheese.  Changing the radius from 2.25 to 4.25 ups the weight a great deal to get 10 PSI. 

Sorry I didn't realize that you were talking about a larger mold diameter.

Epic fail

I could not get the two cheeses to stay straight and the press wanted to cause them to fall.  I had to stop trying a dual press and revert one cheese to the old cheepo spring press and one to the dutch press.  More to come.

Sorry to hear of the failure as I have been thinking about doing exactly that method when I make a larger cheddar batch. 

Do you suppose that if the board between the molds were to be guided, IE allowed to drop with compression but not tip, it might have worked?  I'm envisioning a second base under the first mold with vertical dowels that guide the second board which has loose holes that slide on the dowels - lets it drop but doesn't let it tip further than the tolerance of the the holes to dowels permits.

Quote from: smolt1 on March 20, 2011, 04:36:26 AM
Sorry I didn't realize that you were talking about a larger mold diameter.

I was making the assumption that to calculate PSI you have to include BOTH molds if pressing side by side.  One mold has a Diameter of 4" and one of 4.5" so the two have a combined radius of 4.25".  I may have been wrong but I think it's correct.

Quote from: nhbrewer on March 20, 2011, 12:52:46 PM
Sorry to hear of the failure as I have been thinking about doing exactly that method when I make a larger cheddar batch. 

Do you suppose that if the board between the molds were to be guided, IE allowed to drop with compression but not tip, it might have worked?  I'm envisioning a second base under the first mold with vertical dowels that guide the second board which has loose holes that slide on the dowels - lets it drop but doesn't let it tip further than the tolerance of the the holes to dowels permits.

I think if the pressing arm is in a guide like most Dutch Presses I've seen, then it will probably work fine.  I beleive I've seen pictures of this before somewhere in here.

The issue I had is the poor quality of the press build (my fault actually).  It works 'ok' for one cheese but when adding a second you induce another 'joint' which can move, tilt etc and then the unguided plunger just causes it to 'blow out'.


Some of the problems I had were:

1.  The douglass fir 2x4's I used, while new and kiln dried, actually warped (in the house, in a desert -- hmmm) while waiting to be used.
2.  No guide for the plunger means it moves easily in any direction.
3.  The base of the press did not provide a stable platform and tilted because of the slight warping in the DF studs -- I had to shim the base to keep it from rocking.
4.  The uneven base caused the cheese mold to slightly tilt which increased the arms angle of press off center even more.
5.  The unguided arm tilted in two planes.

The press IS working however and I can see the difference in the press style and the molds used.  So in a way it isn't a complete failure because the cheese will come out pressed at 10psi, will have most of the whey pressed out (it drips past all the holes in the mold and only now after 8 hours does it seem to be slowing way down) and is producing a smoother, nicer looking cheese.

SO all in all, the epic fail was only in trying to press two cheeses but it taught me a TON!  Next on my list sometime in the near future?  A guided style Dutch Press.

Erik

Quote from: OlJarhead on March 20, 2011, 03:43:10 PM

Quote from: smolt1 on March 20, 2011, 04:36:26 AM
Sorry I didn't realize that you were talking about a larger mold diameter.

I was making the assumption that to calculate PSI you have to include BOTH molds if pressing side by side.  One mold has a Diameter of 4" and one of 4.5" so the two have a combined radius of 4.25".  I may have been wrong but I think it's correct.

When you have 2 molds side by side adding the AREAS of the 2 molds will give you the correct weight calculations . Adding the RADIUS of the 2 molds gives you the wrong answer.
Example:      mold  dia = 4 inches ,  radius= 2 inches, area= 3.14*2*2=12.56
         two 4 inch molds have a total area of 2*12.56=25.12 square inches
         If you use the radius instead of the area you get
                  area=3.14*(2+2)*(2+2)=3.14*4*4=46.24square inches.
So when you press 2 molds side by side you are pressing on an area 25.12 square inches not 46.24 square inches. Hope this helps.

Quote from: smolt1 on March 20, 2011, 06:04:34 PM
When you have 2 molds side by side adding the AREAS of the 2 molds will give you the correct weight calculations . Adding the RADIUS of the 2 molds gives you the wrong answer.
Example:      mold  dia = 4 inches ,  radius= 2 inches, area= 3.14*2*2=12.56
         two 4 inch molds have a total area of 2*12.56=25.12 square inches
         If you use the radius instead of the area you get
                  area=3.14*(2+2)*(2+2)=3.14*4*4=46.24square inches.
So when you press 2 molds side by side you are pressing on an area 25.12 square inches not 46.24 square inches. Hope this helps.

Aha!  Now that makes sense!  DOH!

So how do you use a calculator like mine for the same purpose?  Perhaps I'll do some where here as I think using area is going to be better...