Scaling - Hoop & Pressing Weight/Pressure

[FarmerJd]

You may have already read this in older posts, but make sure you (and your husband) understand that the psi produced by the air in the cylinder is not the same as the psi on the cheese.

[wharris]

Weight always needs to be adjusted proportionally as the diameter of the cheese increases.

Actually, if you double the diameter, you quadruple the wieght....  but I am just busting sailor's chops..


I put together a quick spreadsheet that shows that...
why?  I'm bored at the Houston airport....

[coco]

Ok, I'm slowing absorbing the info. We are working out the dimensions of the press on the chalk board.
I'm looking for a smaller diameter mold to increase the psi and I need to know the height of the mold I'll be using.
Dairy Connection has a  Tome mold that is 7.5" x 7.0" x 3.5 (top dia. X base dia. X height). Is that large enough for a 10 pound wheel and can it survive 10 psi ?

[linuxboy]

No and no. Those molds fit maybe 5 lbs max. Look at ullmer's  surplus dairy molds. They have some nice stainless ones.

[coco]

Ullmer's seems to jump from 5 to 20lbs. They do have one that is 8"x 6",but it doesn't say how many pounds, is that big enough?

Just to make sure I understand this, IF I use a 8" diameter mold, I would need approximately 500lbs of pressure for 10psi, right?

 What I'm not understanding is the air compressor psi, is it going to read 500psi and that is redistributed over the 8" surface area? Or, are more conversions needed? I'm not sure if I've worded this correctly, I'm wondering what the air compressor will read when I need 10psi applied to the follower and mold.

[linuxboy]

Ullmer's seems to jump from 5 to 20lbs. They do have one that is 8"x 6",but it doesn't say how many pounds, is that big enough?

Might be barely. That usually fits 8-9 lbs. You might be able to cram just a wee bit more in there.

[FarmerJd]

Just to make sure I understand this, IF I use a 8" diameter mold, I would need approximately 500lbs of pressure for 10psi, right?
 What I'm not understanding is the air compressor psi, is it going to read 500psi and that is redistributed over the 8" surface area? Or, are more conversions needed? I'm not sure if I've worded this correctly, I'm wondering what the air compressor will read when I need 10psi applied to the follower and mold.

Tricky math here. You need to know the following:
1. Pressure put on the cylinder (probably in the 100 psi range)
2. The diameter of the cylinder/piston so you can figure the cylinder piston's area. This area multiplied by the pressure put on the cylinder gives you the net weight put on your cheese hoop.
3. The diameter of the hoop so you can figure the area of the hoop. The answer to #2 divided by this area is the psi on the cheese.


I built a log splitter this week with a 6 inch hydraulic cylinder, a 12 hp diesel engine and a hydraulic pump that produces 2500 psi. I looked at it today and started trying to design a cheese press conversion for it. Thats 35 tons. Maybe overkill.

[wharris]

I have uploaded this before, but I will again here.
this spreadsheet will take 3 variables. 
Cylinder pressure (PSI)
Cylinder bore diameter (mm)
and Cheese mould diameter.


I built it when I was trying to see how big a piston i needed for my 10in wheels of cheese, and maintain a certain PSI on the cheese.

[wharris]

Better picture of my press.
http://cheeseforum.org/forum/index.php/topic,463.msg2261.html#msg2261

Very old school.

[coco]

Wayne, I love your old school press. We considered a lever press when building our first press. I've been thinking about it again, but just don't think I have a space I can dedicate. I don't see how I could make one large enough and portable.

When I looked at the calculator (btw,thanks for the info, I'm on a mac so it took awhile to retrieve, but It really helps!) On the calculator it says "max cylinder pressure", is that the compressor output? Looking at air cylinders on line I don't see any specs to their actual pressure limits.

I've looked at my husband's air compressors and the smallest one that I can wheel in and out of the house is 125psi. The way I'm visualizing it, air compressor has a  regulator, then it feeds into the air cylinder. Or does the air cylinder have its own regulator valve?

[FarmerJd]

The regulator on the compressor would be sufficient for controlling the pressure to your cylinder. You could install an additional regulator at the cylinder but it would be redundant unless you were using the compressor for more than one function. You were also right about the max pressure being the compressor output which you regulate with the regulator. This is how you control the pressure on the cheese. More air pressure- more cheese pressure. You can use Wayne's spreadsheet to plug in a different air psi until you find the desired cheese psi for your mold size.


Kudos Wayne on a great tool.

[coco]

Thanks FarmerJd!
I feel better, I think we can do this!

Btw, I didn't tell my husband about your log splitter. It's best he concentrates on my priorities first.lol

[wharris]

On the calculator it says "max cylinder pressure", is that the compressor output?

That is misleading.  That cell really just represents the pressure in your cylinder. Whatever it is...
You can change that to whatever your cylinder will do...
The table hould re-calculate....