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
7634 lbs of push to get 30 psi. on the follower. This works nice with a
heavy trailer tongue jack, which will give you 8000 lbs of push, and they
are pretty cheap (50 bucks?), and quite durable. You need to weld some
strong brackets to attach it to the cross arm of the press, but thats just a
few bucks.

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)

"Tom S" > wrote in message
om...
>
> "Don S" > wrote in message
> om...
> > >
> > > Yes, but remember that psi = pounds per square inch. You have to
> multiply
> >
> > 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.
>
> 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
>
>