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Post by Freddo on Oct 10, 2015 12:25:02 GMT -5
Hi
I have a plan to build a vibrating screen to pre classify the nibs before passing them through my winnowing setup. I'm unsure what size aperture mesh to use.
I'm thinking of 4 decks, 2mm, 4mm, 6mm, 10mm. The 10mm mesh is there to collect uncracked beans to be sent through the cracker again.
Its the small mesh that concerns me. I read about winnowers which can separate out the germ of the cocoa bean. Is this done using any particular size mesh? does anyone have some advice on the best mesh sizes to use?
Rgds
Freddo
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gap
Apprentice
Posts: 390
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Post by gap on Oct 10, 2015 18:22:53 GMT -5
Sounds like you're further down the track than needing this, but this is a cool video I found a while ago. I always thought if I was going to build something, it would be a good starting point. www.youtube.com/watch?v=YmAIkYhrtD0
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Post by lilypa on Oct 23, 2015 17:31:26 GMT -5
I've been manually using gold panning sieves (1/12", 1/8" and 1/4") or about (2.1 mm, 3.2 mm, and 6.4 mm). I've been told that 1/12" is a bit too small to separate out the germ, but that 1/10" (about 2.5 mm) works well for that. However, you almost need a board (like a plastic cutting board) with vertical 1/10" holes drilled into it and a way to vibrate that nib classification group after classifying to get the germ to fall into the holes for separation purposes.
Love the video Gap posted. Was thinking of creating something along those lines as well. Not sure what the best angle to pitch the screens at would be. Any ideas?
I've heard of other folks using circular rotating screens to classify as the rotation would basically be self-cleaning. I think Rob Anderson of Fresco Chocolate created something like this.
I'd love to hear more of your ideas on what equipment you're thinking of using (i.e. how powerful of a vibrating motor, containing separate sizes, etc.)
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Post by Freddo on Oct 26, 2015 12:39:11 GMT -5
Hi lilypa
At the moment my setup uses two screens attached to a vibrating motor, suspended in a frame on rubber mounts, its rough but it works (for now). My pitch is not as steep as in the video, i made it adjustable and just found what worked best. If its too steep the particles will slide off without going through the mesh, too flat they will dwell and build up. The hard part is getting the mesh to stay flat in the frame. It should be drawn under tension and fixed in place in a steel frame. Mine is a bit wavy and in a wooden frame, which causes the stuff to pool up in the waves of the mesh. I find I need to regulate the speed at which I put the stuff though it. Ive mounted the cracker atop with an electric drill to drive it. If I run the drill full speed the classifier can't keep up so I made a pulsing timer to pulse the drill on and off, like 0.5 secs on, 3 seconds off, and I just tune it accordingly.
The idea is to buy a rotary vibrating screen as you mentioned. they look the absolute business. At each outlet I will set up a winnowing tube which will draw into a common cyclone separator, then into a vacuum source.
It will look like something out of Dr Who but will be pretty efficient. On the top will sit the bean crusher, ideally I can keep it all enclosed to minimise dust getting out. Currently I end up with nibs and dust all over the place, I prefer to do my winnowing outside because of this.
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