Hydraulic Wine Press Out of a Cheap Surge Tank

About: Hi, as a maker in the mid 50's I like to re-build and upcycle things.

Some years ago I still had wine grapes in front of our house. That time I
made wine of them. First I bought a wine press in a hardware store, consisting of a metal frame with cylinder of wooden latches where a stamp presses the fruits down using a spindle. Unfortunately the results didn't convince me really because firstly not much fit into the basket, secondly because much force was needed, thirdly the press result was not satisfying and finally because I had to move up the spindle several times again to add more shim blocks. A professional fruit press that works with a rubber hose was simply much to expensive for my needs, so I decided to look for a simple, cheap and effective solution for my problem. Inspired by professional fruit presses I found a cheap, rather easy to make and satisfying solution that I want to share with other makers.

Warning: Never ever use compressed air to operate the press ! Only operate with water pressure - If the tank breaks under overpressure it explodes when using air and it may injure you and others severely.

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Step 1: Bill of Materials and Tools

The following items are needed to realize the project:
Materials:

  1. 1 Surge tank 50 l with 3/4 " thread connection
  2. 1 Flower pot plate approx. 50 cm diameter as a juice collecting ring.
  3. 1 T-fitting 3/4 " 1 3/4 " Stopcock1 Thread nipple 3/4 " both sides
  4. Teflon Tape
  5. 50 rivets 4 x 8 mm round head
  6. 1 Piece steel plate approx.. 350 x 250 x 3 mm
  7. Flat steel 20 x 6 approx. 1m
  8. 1 Hose nozzle.
  9. Food proof paint
  10. Water tap (System Gardena)
  11. Fruit sack of linen in the size according to the surge tank.
  12. Sanitary silicone to fix the juice ring

Tools:

  1. Sabre saw with blades for steel
  2. Metal drill 8 mm
  3. Metal drill 4 mm
  4. Rivet snap 4 mm
  5. Rivet set round head 4 mm
  6. Hammer
  7. Counter weight for rivet
  8. Welding equipment
  9. Metal bow saw
  10. Flat file
  11. Bench vice
  12. Adjustable Wrench

Step 2: Building Instructions

A new 50 l surge tank can be purchased starting from 60 Euros and that's already the most expensive part.
First you saw a oval ring out of the steel pate that needs to be bent in the next step to be aligned to the surface where you want to cut the hole into the tank. The bending work I did, using a vice and adjustable wrench step by step in small pieces. After the ring is aligned to the curved tank - this means it rests everywhere flat on the surface of the tank - mark the oval hole with a pencil and add some border around to about the middle of the ring to determine the saw line. In the upper part (recognizable by the air valve) you need to cut the oval hole (keep in mind that you need the cap also). Oval, because later the cap needs to be inserted into the hole to cover it during operation. The ring is used as a stop for the cap and must be therefore very stable to withstand the mechanical pressure. The ring should be drilled in position on the tank after it will be riveted. On the Water side a T-Fitting will be applied to which on one side the water inlet will be mounted and on the other side the stopcock to allow dumping the water. On my press the cap needed to be enforced because it started to bend during the first press test. There are surely smarter solutions than my rips I welded in provisional. Now the metal parts need to be painted with food proof paint to save the steel from the agressive fruit acids. Finally you make a hole into the flower pot plate of the size of the tank diameter. Then put the juice ring in 2 ° angle over the tank and fix it with transparent silicon. On the deepest point mount the hose nozzle.

Note: You may think why not welding the ring instead of riveting. Well, the tank material is usually cold formed and therefore stiffened. If you weld it, it can become weak and may not withstand the pressure any more.

Step 3: Operating the Press

Steps to perform to operate the press:
First drain all water, so the rubber membrane is fully down and the maximum fruit space is available. Then insert a linen sack of proper size into the tank and fill in fruit. Close the linen sack with a rope, so later no pomace is pressed out and gets into the juice. Leave a little space so you can insert the cap. Now insert ans position the cap. OK, its time to open the tap and let the water flow into the tank. In any case be careful. If water gets in too quick splashes may occur. Increase pressure carefully. Water pressure may be able to destroy the press. You should stop if the cap-gap gets visibly bigger. Because the cap gap is covered by the rivet ring and is therefore not visible I recommend to mark the cap all around with a pencil in position. The longer you press the less juice will come. because the pores of the fabric will be clogged. This is also much depending on the type of fruit. At a certain time you need to stop adding water, otherwise something may break. But everybody needs to judge for its own. Keep in mind, that the rivet ring and cap needs to withstand a weight equivalent of about two tons at a water net pressure of 4 bars if the average diameter of the cap is assumed at 25 cm ! Depending on your net your pressure may be much higer, so be careful ! Helpful could be to add a manometer into the pressure line to determine once the maximum operation pressure.

Step 4: The Prototype

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