Springs

[INGrandad]

Looking for the stainless steel spring for a cheesepress, anyone have a link for just the spring? Googled, looks like ebay has them, haven't had an account with them for years. I was hoping to find them direct from a supplier. Thanks folks.... Ron

[steampwr8]

Just so happens I have been doing much research on this for the screw style presses.

Ace Hardware carries Century Spring brand springs. Their site is http://www.centuryspring.com.

I have spoken with them and have the following conversion sheets from Century part number to Ace part number on the rack. You want to look for the Compression springs.

I have done the math on the springs that fit our criteria on a 6" mold. You look at the spring's "RATE" which is given in pounds per inch of compression. You should only use 1/2 of the springs length or it may permanently be distorted.  The ones I filled in are most likely to be useful for our presses. So to figure the psi on the cheese I did the following:

                  PSI=(spring length/2) * (spring rate/mold surface area)

The first chart is from Century, the second one is Century's chart after I did my cyphering. As I said I only used the compression springs so look at page 2.

If you go to the Century site their part number is in the second column i.e. 57. Put it in the search box and you will get the specs for that spring. The Ace rack package number is the first column i.e. C-832.

This is how I am using them.

[steampwr8]

An even easier formula to use for any amount of spring compression would be:

                                     Spring Rate (lbs.) x Amount of Compression (in.)/ Surface Area of your mold (in^2)

Using a C-832 I get      45 lbs. x 1.5 in / 28.27 in^2 (a 6" diameter mold) = 2.4 psi max

Still try not to use more than 1/2 of the total spring length when free. In a pinch you can go a little more.

[Chris_Abrahamson]

You could also check out MSC Industrial Supply - they carry a good selection

[tananaBrian]

Shouldn't your formula use "Spring Rate" rather than "Spring Rate / 2" for half compression since you are using 2 springs, not one?  For example "Spring Rate / 2" is correct for a single spring, but "(Spring Rate / 2) * 2" or just "Spring Rate" is for 2 springs, no?

Also, a longer spring with lower spring rate would be superior at keeping the PSI consistent as the whey comes out of the curds and the cheese gets shorter.  The change in cheese height, which is also the change in spring compression, would represent a smaller percentage of change on a longer lower spring rate spring as compared to a shorter stiffer one.

Correct me wherever I'm wrong... maybe I missed something?

Brian

[steampwr8]

You'll have to help me picture this. I believe since they are working in the same plane and pressing on the same lever they work like one in the center. I used SPRING LENGTH/2 not Spring Rate, so you'd limit the compression to 1/2 of total length, which is what is recommended by the manufacturer.

PSI=(spring length/2) * (spring rate/mold surface area)

PSI=(3 in. / 2 ) x ( 45 lbs / 28.27 ) = 2.39 psi

If not then the force would be doubled I think.

I need to calibrate with a scale to be sure.

[tananaBrian]

Yes, I meant "spring length" not "spring rate" in my post!  All I know is that if I have to compress 2 springs, then it'll be twice as hard as compressing one... that's what got me thinking.  I see two springs on the press and the math above seems to be centered around a single spring's length and spring rate.  No biggy.

Brian

[steampwr8]

You might be right which in reality is a good thing. You wouldn't need as beefy a spring to get above 10psi for pressing Cheddars.

I'll have to do an experiment with a bathroom scale to find out.

We've hijacked INGrandad's thread....hope we helpled him too.

[Sailor Con Queso]

IMHO a spring press is a bad investment in time and/or money. As the cheese presses, the springs expand and decrease the pressure that is applied to the cheese. So, unless you stay up all night re-tightening the springs, the cheese will get uneven pressure at best.

A Dutch lever press is easy to make and way more efficient.

[tananaBrian]

IMHO a spring press is a bad investment in time and/or money. As the cheese presses, the springs expand and decrease the pressure that is applied to the cheese. So, unless you stay up all night re-tightening the springs, the cheese will get uneven pressure at best.

A Dutch lever press is easy to make and way more efficient.

Or a pneumatic press... I've got a compressor that maintains 80-130 psi in the tank.  I'm going to do some research and find out if I can come up with a cylinder bore that will be able to press with high enough pressure.  Example:  Cheddar pressed at 172 kPa (25 psi) requires the equivalent of a 707 lb load on a round 6" diameter mold.  I think that's the worst case that I've discovered so far... but it would be nice to have fine control over the light pressures (0 to 3 psi) while at the same time being able to exert some really high pressures when necessary... discounting those gigantic 10" or 12" wheels that pro's make that is.  I think a hydraulic jack is probably the only way to press those cheeses ...but who knows?  I'm a complete newbie and just thinking ahead... A 6" wheel is A-OK with me!

Brian