Hello:
A friend made us a very nice dutch cheese press last year. It turned out a little bit larger than I expected, and I don't know how to calculate the pounds to use it. My bathroom scale, when placed under the press beam, gives me different weights and errors out. Also, the press beam is adjustable up and down and when I put a cheese mold under it, it's higher up than when I put the scale under it. Would this change the pounds of pressure as the press beam lifts up and down?
Can anyone help me with a mathematical equation to figure out the pounds? I have read some other articles on this forum about calculating, but I'm still stumped. ??? ???
Here are some dimensions:
The vertical "press beam" that comes down on the cheese is 36" long.
The press beam attaches to the lever at 11" from the pivot point.
The entire lever arm is 48" long
The first notch is 18" from the center of the press beam (vertical part)
The first notch is 28" from the pivot point
The notches to hang weights on are spaced 4 1/2" apart
I used my postal scale (my only accurate scale -10lb.) under the press beam and it weighed 1 lb. 5 oz.
With the press beam and lever attached and no weights, it weighs 6 lb. 11 oz.
I think those are the necessary measurements to "plug in" and calculate. I need someone with more left brain matter than myself to tell me what weight to hang on the first, second, etc. notch to give me 15 lbs., 30 lbs. etc. Would you also share how you calculated it...not that I will understand it, but I'd like to try.
I've read about PSI and how important that is, but my cheese recipes don't call for PSI, just pounds.
I would like to use this nice press. Thank you so much!!!!
Judy
PS... If a picture would help, let me know and I will post it.
All you care about is the diameter of your follower\mould and kg\lbs of force at the pressing end.
Determining your force multiplier is easy,
Pull out your wight, measure somthing small and hang it.
Put the wight on top of the mold and measure the force being applied on it.
Devide between the two and there you go.
Judy, the pertinent measurements are these: the distance from where you hang your weight to the pivot point, divided by the distance from the pivot point to where the presser arm (that applies the weight to your mold) is attached. This will give you your"mechanical advantage". This number times whatever weight you hang on the pivot arm is the weight pressing on your cheese.
So, if you hung a weight at the very end of your lever arm, which is 48", divide that by 11", your distance from the pivot point to the presser arm, so 4.3636. Every pound you hang on the end of your arm with give you 4.3636 lbs. at your mold, theoretically, but there's usually a little friction that lessens that slightly.
To determined pounds per square inch, it's your total weight at the mold divided by the diameter of your mold divided by pi (3.1416); so a 7" mold would have approximately 1.65 psi if you hang a gallon jug on the end of your lever arm.
Dave in CT
Judy, could you post a picture of the press
Here is a picture.
Thank you for such an easy way to figure this out! Here is what I am understanding:
The measurement from pivot point to 1st notch is 28". I divide 28 by 11 and get 2.5 lb. added per pound hung on this notch. If I need 15 pounds, I would add 6 pounds of weights, right?
Each additional notch is 4.5" away from each other. If I need 30 pounds of weight and I cannot evenly divide that into one of my notches, do I add a fraction more or just a hair less? I suppose now that I have a way to determine, I could continue to measure and hang the weight without using a notch. . Does it matter?
Thanks very, very much!!!
Judy
OK I need the same type of help, what type of multiplier do i get with the pulleys?
Or do what I do: I have a hook on the end, and I hang a water jug from that. I just vary the amount in the jug for less weight, hang a second jug for cheddar. My press has a 5:1 mechanical advantage, with a block and tackle form the end of the arm to the base, which doubles that, so 10:1, When I hang two gallon jugs on the end I have 166.9 lbs on the presser arm, which gives me around 7.5 psi on my 7" round mold, enough for cheddar.
Dave in CT
Do I need to consider the weight of the presser arm and plunger and add that to my calculations? I found the calculations for a dutch cheese press in another post:
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)
You said you have a 5:1 mechanical advantage. How did you get that? What / how does that apply to determining the weight your press is able to press?
I am sorry for these elementary questions, but I want to understand. :) Judy
Yes, you should calculate the weight of your presser arm into your total weight. I'm pretty casual about my weight calculations, usually just using half full, full, and two jugs as my pressing weights. I got the 5:1 mechanical advantage on my press by making the presser arm attach at 1/5th of the way along the lever arm. This doesn't give me much room, I can just fit a seven inch mold in the press. But that's a good size for a four gallon batch, and my electric roaster does four gallons perfectly, and I have a strainer that exactly fits my six gallon bucket and holds the curds from a four gallon batch nicely, and that also fits my ready-cut cheesecloth. My press has a 5:1 advantage on the lever arm, but I doubled that with a set of pulleys and a rope. I hang the jugs from the rope. My press broke the first time I put 2 jugs on it, and I re-built it doubling the lever arm. Seems to be holding up well now.
Dave in CT
Jasper, you have a 12 to 1 MA if I am looking at your pulley system correctly. (6 to 1 without the pulley using the 2x4 plunger in the picture.) Just multiply the weight on the end by the MA and you have your approximate weight on the cheese. If you have a double pulley system it may be more than that, but I cannot tell from the picture.
Judy, If you put your weights on the very end of your arm you will have an MA of close to 4 to 1 (estimated by measuring your picture). You can just always multiply the weight on the end by 4 and that will be the weight on the cheese. The arm and plunger weight is somewhat negligible. Nice press. Good luck.
Judy the weight of the lever is somewhat negligible, but if you want to add it into the equation just put your scale where the cheese goes and measure the weight with no weight on the lever arm .That is the weight to use where the equation says "weight of arm and plunger". With the size and length of your lever arm it is probably not negligible when you are pressing with low weights ( like under 15 lbs).
OK...Thank you for making the math so easy for me!!
My next question: by looking at my press, is there a way I can press two 2 lb. molds at the same time?
If I make just one large mold (5 lb.) can I cut it in smaller pieces, wax and age them?
Judy, Yes you can stack them if there is enough room under the plunger. If not you can do them side by side but the weight is cut in half. It is best not to cut them but some have done it myself included. The inside surface is not going to be conditioned like the outside rind.
Smolt1, that was a very valid point about the low weight pressing. I am accustomed to cheddar pressing on large wheels where it is statistically negligible. The idea you gave about weighing with no weight is a great solution.
Farmer
Thank you Farmer, there is the tie point on the upper arm and a total of 4 pulleys.
Farmer, you said I could stack them. Is this how I would stack the molds? These are 2 lb. molds. Would I just put them as I did in the picture and then use one follower on the top cheese? I would still wrap them individually in their own mold, stack one on top the other and press with one follower? The pressure does not change when done this way, right?
If I put them side by side, do I need to place a peice of wood over the top of them, so they both get pressed down? What keeps one from getting a little more compressed than the other? Or, do I need a special attachment that allows me to have 2 plungers on the end of the arm? I'm also understanding by what you said that I need to double my weight when done this way...if it calls for 30# I need to use 60#?
Thanks!!!
Judy, the way you have them stacked with the 2 molds touching, will not allow transfer to the mold on the bottom. The lower mold needs a follower and some sort of spacer, a piece of wood or a PVC pipe, so that the upper mold pushes down on the lower follower. Then whatever weight that you use will be the same for both molds.
Ditto what Sailor said or you could put an extra follower in between the two cheeses. I have done two cheeses in one long hoop (pipe) before but it was hard to get them out. Far easier to follow Sailor's advice. Side by side means you have to balance the two sides perfectly which can be tricky but is "doable". and yes you are right about doubling the weight.
Jaspar, you probably have an MA of around 24 or greater (not counting friction) depending on your setup. The best way to determine it is to measure the distance the end of the string moves down divided by the distance the arm moves down at the same time. In other words, with no weight on it, make a mark on the string and pull it one foot, then measure how far the arm went down and divide. Multiply this times the press MA (6:1). Let me know if that doesn't make sense.
I've been reading this post silently but now I have to ask a question for clarification.
Sailor/Farmer
When pressing using stacked molds with correct followers - are you saying that you double the pressure? So - if the recipe asks for 35 lbs, you use 70 lbs?
I was unclear if the double weight applies to the stacked press or the side x side only.
Leah's mom, Here is something that might help the weight and pressure discussion.
Weight and Pressure
When you put 1 tsp of sugar in a CUP of water it tastes different than if you put 1 tsp of sugar in 1 GALLON of water. The difference is the different concentrations of sugar. In the same way if you put a 1 lb weight on cheese curds in a mold that is 4 INCHES in diameter the effect will be different than if the same 1 lb weight is put on a mold that is 7 INCHES in diameter. The difference is the different amount of pressure on the cheese. To calculate the pressure you need to know 2 things. The WEIGHT(that is applied to the top of your mold) and the AREA (of the top of your mold). Then the PRESSURE = WEIGHT/AREA. The units of weight are the pound or kilogram. The units of area are the square inch or square centimeter. So the units of pressure are pounds per square inch (PSI) or Kilograms per square centimeter.
When you stack the molds you use the same WEIGHT as you would use for 1 mold. when you put the molds side by side you double the WEIGHT. In both cases the PRESSURE stays the same, which is what you want.
Thanks you, smolt. That is exactly what I thought was the case but I wanted to be sure I was interpreting that correctly.
Farmer you are the Man! Makes prefect sense Thank You!
Jaspar
Can anyone share a picture pressing 2 or more molds? I'm not picturing what kind of follower I need. I am thinking the followers I have will not work because they are not flat. Thanks, Judy