homemade wine press

Don,

I know that a hydraulic bladder press operates at about 30psi, so if you have a 10" diameter basket, that's about 78 sq in. Times 30, that's over 2300 lbs of weight on a one-to-one lever system. Note that as drawn your press has an effort arm (pivot to weight) about three times the length of the resistance arm (pivot to basket). This gives you a mechanical advantage of 3:1, so you would only need 1/3 the weight calculated. With a long enough lever arm, you could probably get the weight down to something manageable, but be sure to build stoutly.

I actually know of an antique press of this design, probably from the

HTH, Mike MTM

D> |

Mike, Are your sure about the calculation where you arrive at 2300 pounds? Wouldn't I only have to think about the 30 psi and ensure I get that pressure on my round (or square) pressing plate?

Actually that does sound about right if you think about a 1 foot square plate. That would be 144 sq inches, times 30 psi for 4320 pds. Both numbers just seem like alot more weight then I thought it would need. Even with the 3:1 multiplier that would be 767 pds in your case and 1440 pds for my mine.

Is the 3:1 ratio set by the distance from the start of the cross beam to the down tube and from the down tube to where the weight is suspended, B/A in the below:

| B | B | |o==============o============================o

I was considering a single 2x4 for the cross beam but perhaps two would be better, something like this when viewed from the top:

|-------------------------------- hinge | O weight |--------------------------------

Don

I run my bladder press at about 3 Bar, which is closer to 50 PSI. You need a hydraulic ram or a screw device with a _long_ handle to achieve that kind of pressure over a large platen. A simple lever arrangement won't cut it.

Correct.

Yes, but remember that psi = pounds per square inch. You have to multiply the 30 by the number of square inches of plate.

Building something like this from scratch isn't easy or cheap. That's why I suggested renting or buying a press. You could always sell it if you decide winemaking isn't for you.

Tom S

Don, I saw ,in Tuscany, an ancient press like your sketch that used a massive oak beam ~25 ft long. But it used a large wooden screw under the "free" end to regulate the rate of applying pressure. There was a large capstan like device to turn the screw.

So the options are to increase the leverage or decrease the size of the plate (platen?). In order to get the same volume in the press you could switch from a 24" diameter tube that is 2' high to a 12" tube 4' high.

Don

Not a good idea. The grapes at the bottom of the 4 ft press will hardly be affected.

No, it's like this:

A B C

O----------O-------------------------------O Hinge Platen Weight shaft

The distance for the "platen lever" is A-B, and the distance for the distance for the "weight lever" is A-C. The mechanical advantage would be A-C divided by A-B. (This is called a 2nd class lever. A seesaw is a

I would use a pair of 2X6's, _on edge_, about 8' long.

Don, I have to agree with Tom and Darwin on this, that it is a lot of work & expense (& design effort) to make a practical press from scratch. Over the years, I've built two. While each worked (works!) well, it was probably more hassle than it was worth. I now have a shiney new bladder press (although this year's crop was too meager to warrant getting it dirty :-( ) It's certainly a doable project, but not everyone would want to undertake it. Someone who's very handy with tools & design can have a fun time doing it, but but someone who isn't handy might well be frustrated with the result.

HTH, Mike MTM

You didn't work the numbers on that. Halving the diameter and doubling the length yields a volume that is _half_ what you started with. Using your example, you'd have to increase the height to 8' to retain the same volume.

Tom S

The pressure required goes up as the square of the radius. A 12" tube is to a 24" tube as 36 is to 144, or 4 times the area. To put 30 psi on a 24" circle takes 12,667 lbs of pressure, whereas you can get the same psi on your follower with only 3167 lbs if you stick to 12". The 18" diameter takes

One benefit of building something like that is if you get into cheese making, you can use a piece of 12" pvc in place of the basket, with a perforated board underneath to make a real nice cheese press for big 25 lb wheels of cheddar or gouda, which age the best. You can't buy that extra aged, raw milk cheese in the stores, and its perfectly safe after only 3 months age. After a year it is outa site! (Have tasted it and am in process of making some!)(I had no difficulty trading wine for 2 minute old, warm, fresh, jersey milk)

To decrease the serface area by half, you would need a diameter of just shy of 17".

email: dallyn_spam at yahoo dot com please respond in this NG so others can share your wisdom as well!

So if I was to use a 8' 2x4 and put the platen post at the 2' mark I would have an AB of 2 and an AC of 8'. The multiplier would then be AC/AB = 8/2 = 4 ?

What's the ratio of movement of point B in relation to point C - if I move C a distance of 2', how far does B move?

Also, is 30 psi the desired pressure would 20/15 or some other number do?

I'm beginning to agree with Tom as well. I'd prefer to save the $250 Cdn but it's the time that's the killer.

Don

That's right. your "mechanical advantage" is 4.

The ratio of movement will be the inverse of the mechanical advantage. In other words, if the force on B is 4 times the force (weight) on C, then it travel 1/4 as far as C. That's 'cause you don't get something for nothing in this universe. The basic rule is: Force (B) X Distance (B) = Force (C) X Distance (C).

Good question. I never really knew the pressure I was applying with a screw press, but my bladder press has a pressure relief valve which is set at 3 ATM, or 45 psi. I think this is what Tom said he runs his up to. The instructions for mine say to operate at about 30psi, but when I ran the bladder press at a small commercial winery, we went to about 2.5 ATM, or 38psi. It's also a matter of personal preference, and how hard you're willing to squeeze the must. Basically, the harder you squeeze, the more wine you get, but at some point the quality starts to suffer. Wines can be "overpressed", but the greatest drawback to underpressing is probably low yield. I think 15psi is unreasonably low, probably 20psi too. Especially for whites.

Luck, Mike MTM

So I worked out a test case. A 12" dia basket would work out to:

pi X d = 3.14 X 12 = 37.68 sq in

at 30 psi we get:

If we get a multiplier of 4 by using an 8'x2"x4" with the platen at 2':

Which is doable especially if you plan to add your own weight by stepping onto the end somehow. If we calculate at 20 psi then it gets even better:

This is really theoretical at this point, I'm going to keep my eye open for a used press.

Don

Wups! Area = (radius)² x 3.14 = 36 x 3.14 = 113 sq in (You calculated the circumference.)

Actually, it's 113 x 30 = 3390 lbs

No, it's 847 lbs

No, it's still 565 lbs. You'd still need whatever you weigh plus ~400 pounds.

That's the right idea IMO. BTW, a little bigger than you think you need is better. Plan ahead.

Tom S

I too have seen one like you describe, it was from Austria... the tour guide said that men or oxen would turn the screw to apply pressure.

The one in Tuscany was different. The weight of the beam provided the pressure. The capstan screw lowered the beam and thus controlled the pressure

Silly me. I should have caught that because the units wouldn't have come out in square inches, didn't do as I was taught.... don't tell Mrs. Gilljie.

Correct on all accounts.

One thing bothers me though, on the one had we talk about hand squeezing grapes or using a 3 pail system with one pail being filled with 70 pds of water, but when it comes to a press nothing less than a billion pounds per square inch will do? Seems on the one hand the good enough will do but on the other it has to be perfect??

Don

Another idea dawned on me while considering that the problem in the lever style is the weight on the end. Instead of the lever, I could use a car jack and the weight of my house.

Since I will be working in my basement, I could use a sissor type jack within a two piece pillar above the platen/press:

| Floor Joist | ---------------------- | | | | 4x4 brace against joist | | ----- X---- Sissor Type Car Jack ----- | | | | 4x4 brace | | | | | | | | | | | | Press Basket |-----------| | o o o | | o o | | o o o | \---------------/ \\

As long as the sissor jack was firmly anchored to both 4x4s so it wouldn't fold it should be safe. Perhaps a bit awkward to fit altogether but simpler and cheaper, hmmm...

Or... perhaps one of those poles that are used to shore up basements. Theie name escapes me but they come in different sizes and have 4" steel plates on either end. They have the required coarse threaded screw in them and are fairly low priced ~$20 or so if I remember correctly.

Don