Off The Wall Press & Pressing Weight Discussion

[steffb503]

I have been making hard cheese with 2 gallons of milk. One because that is how big my pot was and two that is haw big my mold is. I now have my wonderful cheese vat and can make large batches.
My question is the pressing weight. If I am making one wheel from say 5 gallons of milk do I need to in crease the weight that I am pressing it at?
In the cheese makers manual she talks of the dutch press and using 10 lb weight, is that a 10 lb weight at the end of the arm or 10 lb of pressure?
I am using an off the wall press which is basically the same.

[zenith1]

Hi Steff- since you are progressing to the commercial end of cheese making you probably need to start thinking in terms of PSI when referring to pressing. So to answer your question when you progress to a bigger mould(larger diameter) the amount of pressure it is going to take will increase with the surface area of the follower or mould that you will be using. A lot is explained in this thread http://cheeseforum.org/forum/index.php/topic,5800.msg42219.html#msg42219. Also I have attached a very helpful chart for quickly calculating what you will need based on the mould diameter that you are using. I can't take credit for that great chart(it might have been Wayne) but it will serve you well.

[FarmerJd]

The short answer is that as long as you are using the same size hoop, there is no need to change the weight. If you have a wall press, you are in good shape for increasing the psi per the chart that Zenith linked. Good luck.

[steffb503]

OK
so now I am totally confused.
If the recipe calls for 10lbs psi I can figure that means on the follower.
If it call for using a 10lb weight is that the same thing or do they mean hanging a 10 lb weight off the arm resulting in pressure upwards of 100psi?
I am using the off the wall press which has 4 different slots to put the plunger. Allowing for 4 different pressures with the same weight.
I love the ease of the press but have never really thought about it, just followed the recipe.

In the very nice chart it has 10lb weight giving .97 PSi am i reading that correct?

[FarmerJd]

If you hang 10 lbs on the arm you will get a much higher weight/pressure on the cheese than if you just put the weight on the cheese itself as the recipe says. The recipe does not refer to psi unless it says so.


Can you provide the following information so we can help you figure this?
1. What size hoop do you press in?
2. How far is it from the end of your press arm to the pivot point or where it is pinned?
3. How far is it from the plunger (the vertical post that presses the cheese) to the pivot?


Hang in there; you will get it. You are really blessed to have such nice equipment.

[tnbquilt]

We put a bathroom scale on ours, and moved the weights on the arm to see where it pressed what weight. Then I marked it with a magic marker. Not very technical, but it didn't take any math to figure it out.

[steffb503]

Here is the press I am using
http://www.cheesemaking.com/store/p/50-Off-the-Wall-Press-Plans.html

It has 4 different option to place the plunger
They are 3",  4", 4 13/16", and 6" from the center of the pivot. The whole arm measures 30" from the center pivot to where you place the weight.
The chart gives placement of weight and weight itself to achieve said pressure.

I am using a mold with a 6" diameter and 4 gallons of milk.

My problem occurred when making a recipe from the Cheesemkers Manual, I just got the  book.
It says using the dutch press, Which in principle is very much like what I have, use 10lb weight. But it does not tell my how much pressure I need. I could then look on my chart to find the right spot.

Or Do all dutch presses have the same length arm and plunger?
Mine having extra slots makes it easy if I know how much pressure I need.

[smilingcalico]

Steff, I might also add (since I can't tell if you understand this) that the 100 pounds you get from the plunger doesn't equal 100 psi.  In order to figure that, you need to figure out the square inches of the mold, then divide that into the 100 (or whatever # it may be) in order to figure out the psi.  Sorry if you already knew that.

[steffb503]

Yes I should have simply said 100 lbs of pressure. I did know that . But thanks

[KosherBaker]

Or Do all dutch presses have the same length arm and plunger?

Definitely no? Here are some notes I took from reading the archives of this forum:

Dutch Style Press Calculations
Mechanical Advantage (MA) = Total Arm Length / Distance from Plunger to the Fixed Point in the back (fulcrum)
Weight Applied = MA * Weight + (Weight of the Arm and Plunger)

Mold Calculations
Area = 3.14159 * radius squared
PSI = Weight Applied / Area

So to calculate the total area of your 6" mold the formula will be:
Area = 3.14159 * 3 * 3 = 28.27

The Mechanical Advantage will change depending on where you hang your Weight.

[FarmerJd]

I am going to figure this using the 30" arm and the 3" distance for the plunger. That means a mechanical advantage of 10. If you hang 10lbs on the end it will give you 100 lbs at the plunger. For the psi with this weight, divide 100lbs by the area of your 6" hoop (28.27 sq-in) and you get 3.54 psi. You can see this on the spreadsheet Zenith posted. I would start the pressing at 1-2 psi for about an hour, then increase it to 3-4 psi for another 1-2 hours then just put whatever you can overnight.
The scale idea is a good idea for checking it until you get a lot of weight on it. On your press, anything over 25 lbs would probably max out your bathroom scales.
I hope that helps. Good Luck.

[steffb503]

Yes that does help.
Thank you all.