Separating the sticks, stems, stocks, and milking the flowers.. Not too fine!

Hello all,

I’m kicking around better ways to separate stalk and stem from biomass. We are a butane extraction lab in Oregon. We have been getting biomass that had been stabilized in many different ways. The worst so far is the stuff that’s been harvested with a bean chipper or been sent through a wood chipper.

Im thinking screens are the best tactic…

Any bright tried and true practices? Any innovative ideas?

Removing the main stalk and major branches mechanically is relatively easy, even on a low budget, but branches less than 1/4" are rather hard. While I have a few theories, I haven’t seen any equipment on the market so far that will pull just flower at a reasonable rate.

Depending on your volume their products might be overkill. Biomass is fed in the top, everything vibrates, product smaller than the mesh falls through, product larger than the mesh is discharged out a separate port. Some good stuff may be rejected, and some bad stuff may be accepted, but it is a hell of a lot better than two people holding a screen into a pile on a tarp or something similar. It is also an enclosed system which will help with breathing in hemp dust.


Just a screen and sifting is the most economical way. Takes a ton of time and labor for something I’m not sure makes your end product any better. I have worked at two different extraction companies, one that sifts and one that doesn’t, for supercritical CO2. I haven’t seen any problems that came from not sifting although your chances of picking up thermolabile compounds is higher. Not sure if this is an issue with butane, but we had oxidation issues from extracting at too high pressures and then purging at way too high temps.


Screens will grind and separate. Shaker tables

I like brainstorming new ideas! And it didn’t take long to think this one up either!

OK, imagine this in your mind’s eye:
A row of stainless steel straws/tubes of progressively larger diameter, and the tip of the straw has been slightly sharpened. The tubes don’t need to be much longer than 6-12 inches for this idea to work, and I would think a shorter tube would have less chance to clog up, while also allowing for the inconsistent shape of the stalks.
The tubes can be set into the middle of a collection table for a clean job. The bottom of the tube would stick out the bottom of the table, with a bin or bag under there to collect the debris OR you could attach a shop vac or something similar to the tube(s). You could also have two spinning rubber wheels to grab and pull the stalk through (like a baseball pitching machine), and that would probably work faster and more efficiently.

Select a tube that fits the stalk snugly, but not too tight. When you feed a stalk through the tube, as it gets pulled through, the sharp top edge slices off the plant material, leaving a bare stalk to shoot out the bottom. The plant material then simply falls to the side into the collection tray. One side of the tray could have a funneled edge to collect everything into the tray, or you can just lift the material out by hand.

This also reduces manhandling the plant, keeping buds and trichomes undisturbed. It would also reduce the amount of residue left stuck to the tubes, since they would come into less contact with sticky parts of the plant.

Another idea is to apply the same principle to something that looks like a bench vise, with different size holes in the jaws of the vise, depending on the diameter of the stalk. The rest of it follows the principles described above, but instead of a number of different tubes, you have the adjustability of the vise opening, possibly giving it greater versatility and ease of use.

Yes, there is still some manual labor involved, since you have to feed each stalk in one at a time. But you’re not having to trim each one by hand, the machine does the work. All you have to do is feed in the stalks and collect the net product. The unwanted sticks are already in a bag or tray, or with the shop vac setup, you could just open it up and dump the debris into a bin.

I would probably suggest using as much stainless steel as you can in the setup, for longevity and ease of cleaning. It also lend the machine to being more sanitary than plastic, I would think. And just about everything needed to put the contraption together could probably be found in a hardware store, so repair and/or replacement parts would be easier to find.

As a retired auto mechanic, it’s easy to see this setup in my mind’s eye, but if you can’t imagine it yourself, I could try to elaborate further. But there’s not much else to add, it’s a pretty basic thing to set up, I’d say.

How does this sound to you?

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Those already common practice, and ive been doing it for years with a rubbermaid container. Just drill holes the size of stalks and pull thru, plant material falls into the bucket.
The problem i think they are having is material that has been shredded with sticks in them.

My solution is getting 4-6 1/4" SS mesh and place them on top of each other about 1/4" away from each other. Offset the layers so the squares dont match up, it should allow plant material to fall thru but the mesh should catch most of the sticks. Make a device that allows u to move the mesh planes around and be able to line them up to eject all ur caught sticks. Put it all on a vibrating platform and it should be easy. Havent built one but thats what i would do

We’ve just installed a system in Oregon that separates sticks and stems from the flower, it’s given us great results. Thinking about setting up some toll processing for the farmers who chose to chop material this year (Seems like the new norm nowadays).

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did you purchase said system or build it from scratch?

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I built a rectangle out of 2x4 about 3’ x 4’ and stapled a screen to it. The screen was super fine though. I put it in a super sack and used it like a washboard. Rubbed the material over screen. The sticks and stems didn’t go through. It was labor intensive. It made a fine powder. I was thinking if I used larger screen and made the frame as big as a sheet of plywood and maybe with legs. Could have finer screen under. If we could make it shake some how even better. The chopped stalks would not go through the screen…

It was purchased, Its a pretty big system and can handle 2-3000lbs/hr