I took the opportunity yesterday to head out to the local public hunting grounds. While I was there I saw 2 frogs, a fat mole, and a house cat. I spent some time foraging around. I found a black walnut tree (though I didn't collect any this time) a handful of soybeans scattered across a harvested field, and lots and lots of rose hips.
I had been meaning to build a press to extract oil from foods for some time. Yesterday I finally made that dream into a reality, and then after one use I broke it.
I wanted to make something simple and use my h-frame press to apply the force. I poked around for the biggest drill bit I could find, and I found one that was 1-3/4". I poked around in my metal stock and found a short bit of copper rod that, at one end, was the same diameter.
I make aluminum castings a lot, so I started with a bit of aluminum round stock I had recently cast. I use various steel molds, this particular casting is poured into a short length of steel stock and then pounded out when cooled.
Next I put the stock in my lathe (which required a bit of reassembly before use.) I bored out a 1/2" hole to the depth I wanted, then moved right on to the big 1-3/4" bit. The fit with the copper rod was quite good.
Next I drilled a hole into the side of it to allow the fluid to escape. I marked the depth on the rod with a sharpie marker and then gave both parts a wash.
I found a metal baking pan to work in so that the extracted goodness didn't just drip on the floor. I put it all together in the press, applied some pressure and, MAGIC! The resulting juice tastes just like fruit roll-ups.
And then a bit more pressure after that and everything - seeds, stems, pulp - started coming out the same hole as the juice. I needed a screen of some sort, and found one to salvage out of a water tap in my scrap pile.
I put the screen in the bottom and filled the cylinder with rose hips again. I pushed those contents down with the copper ram by hand and thought, 'hey, if I push it down like that I can fit way more in here.' This proved to be a fatal flaw to my plan. The copper rod subsequently wasn't sitting deep enough in the cylinder, and when I applied hydraulic force it bit into the wall of the aluminum cylinder and broke it. Boo.
The whole project, which included a bit of scrounging and machine re-assembly took about 3 hours. I do plan to make a second one and re-use the copper ram.