Micro hop plucker/stripper

Monday, September 17th, 2018

The need

You may have noticed that I am a bit obsessed with hops. Currently, I am running three small yards for our experimental hop breeding program. Hops are wonderful to grow, but can be a real pain to pick. Hand picking takes about 1 hour per plant – meanwhile, picking machines cost hundreds-of-thousands of dollars and can typically be as big as a warehouse. There are a few “smaller” machines on the market, but the size and cost is still prohibitive for the hobby grower.

The build

Picking fingers

The core of any hop harvesting machine is the picking fingers. These metal loops are used to grab on to the hops cones and pop them off. They need to be strong, flexible, strongly attached, and have to correct angle. I practiced making some of my own – but, due to time constrains, opted to purchase some from Sea to Sky hop solutions.

These are replacement fingers for the Wolf 140/170 picking machine. 56 fingers was enough to cover 4 picking bars about 30″ long.

Spindle

To hold the fingers, I simply created a spindal with 4 bars created from cheap 2×2 lumber. These are spaced around the metal shaft with 8″ plywood circles and a few more 2x2s. Super simple and cheap, but more than strong enough for a picker this size.

Just be sure to chamfer the edges of the 2x2s to mount the picking fingers … before you put the spindle together.

Box

The spindle is mounted inside a 30×36″ box using inexpensive pillow bearings. The box needs to be ridged and heavy enough to keep from moving when you pull the heavy hop bines through.

The box is also important as it keeps your hop cones from flying across the yard when they are plucked. Originally my box was open, but I quickly added a hinged lid with neoprene “car wash style” flaps. This looks a bit funny, but effectively keeps most of the cones contained.

Power

For power, I used a simple 1750rpm, 120v motor. This needs to be slowed down significantly for the spindle to run safely. A 15″ pulley slows the speed down to a reasonable 175rpm (about 3 rotations per second).

As a basic safety measure, I hooked the motor up to a cheap dead-man switch. This way it only runs when your foot is on the pedal.

Sorting

The machine only strips the hops. Sorting done separately, but isn’t difficult. We simply poured the hop/leaf mixture in front of a box fan – this blow away about 80% of the leaves.

Success?

The hop stripper reduced the harvest time for the Barber hop yard to 10% of last years effort – half a day and the whole yard was down, stripped, sorted, and ready to dry.

Pros

  • Stripping the cones works extremely well (much better than expected)
  • Very stable – no need for extra weight
  • Safer than expected. Does not grab fingers. Dead-man switch stops it quickly.

Cons

  • Sorting cones from leaves needs to be improved
  • It will sometimes grab tangled bines (especially near the ends)
  • Small, but still bigger than I wish (pain to store the 364 days its not in use)

Ideas for the next version (Mark II)?

  • Do we even need the heavy box?
  • Idea: a simple spindle and guards mounted above the bed of a pickup truck
  • Would be ultra stable and portable

17 Responses to “Micro hop plucker/stripper”


  1. Steve Hogath Says:

    I have a small hop yard that requires a micro picker such as yours. Would you have plans available for your picker to aid me in my building of a picker. Any help would be greatly appreciated
    Thanks steve


  2. nagmay Says:

    Steve,
    Sorry, I don’t have any plans at this time.

    Just made it up as I went along, but the pics should give you a good place to start. The most important aspect is to keep the speed down (<200rmp) and have some basic safety items like the dead-man pedal.


  3. nagmay Says:

    To be honest, I will probably re engineer the thing before the next harvest.

    As mentioned, mounting the spindle on a truck bed would give it much more stability and make it super portable.

    Let me know if you have any specific questions. How big is your hop yard?


  4. Frank_Z Says:

    Hi Gabiel,

    great idea, especially with buying/using original picking fingers.
    My hop yard is about the same size as yours, I just wonder how well it works with mature plants/tangled bines (up to 10# of hops on one plant with one string per plant and with single leafs up to almost a foot in width).
    If it works well it will save me days.

    Thanks

    Frank


  5. nagmay Says:

    Frank,
    With the size of this build, the tangled tops are more difficult. Our trellis is < 20', so we get that issue. I cut the tops into sections to more easily feed them through. However, it was still much faster than picking by hand. That said, adding more fingers, or a 2nd spindle could really help.


  6. Mark Says:

    I see you used flange bearings for the metal rod to turn in, but how did you attach the 8 inch discs that hold the picking finger barrel to the metal rod to prevent slip and slide issues?


  7. nagmay Says:

    Mark,
    Behind the disc ends, there are simple 2×2 cross braces. On each end, I drilled through one of the braces, rod, and out the other side. A small bolt then holds it all in place.

    There are better solutions, but it hasn’t slipped yet.


  8. Victor Shaffer Says:

    For your picking fingers, how many sets do you have on the spindle? Also, did you buy the picker bar complete or just the fingers and then attach them to your spindle? I appreciate you posting this online – very helpful for small growers.


  9. nagmay Says:

    Victor,
    For this short machine (4’wide), I needed 56 picking fingers, that’s 14 per bar.

    The bars are completely home-made. They are just fir 2×2’s with the corners shaved off. Makes for a perfect fit. I then used a simple metal strap and screws to hold them on.


  10. George Lean Says:

    Outstanding job on box. If possible, please call me.
    George 706-593-6282


  11. Tabby Says:

    Very, very cool!


  12. Jim Spencer Says:

    Do have these for sale?


  13. nagmay Says:

    Jim,
    No – this is more of a diy project.However, if there is continued demand, I would consider putting together some blueprints and part lists.


  14. Konstantin Konstantinov Says:

    Can you share the scheme?


  15. John S Says:

    Hi
    I just started my second year of hopyard and will need to start thinking about harvesting. I am wondering if I could get more specific pics on your build?
    What horsepower motor are you using?
    Have you put in the second stripping spindle.?
    Thanks John


  16. nagmay Says:

    John,
    How many plants do you have? Hand picking works great, and is probably the best option until you have over a dozen plants to pick. On the other hand, a full size yard with hundreds of plants will need something quite bigger.

    I don’t have specific plans for this, as it was cobbled together quickly. If I get around to upgrading this year, I will be sure to take better notes.

    The motor is quite small (1/3hp), but slowing the spindle down to 180rmp results in more than enough torque.

    As for a 2nd spindle, it would absolutely speed up the picking process, but would also complicate the build.


  17. John Says:

    I have 200+ plants In this year. 7 from last year.
    I’m thinking a double spindle would be best. I don’t have a budget for a bigger bought harvester. I’m hoping the small micro breweries buy what I have. There are plenty of them around. I may plant a few more fugal hops next year just to even the plantings.
    Ke ep me in mind when you start your modifications. I’m considering adding a screen and blower to help sort.
    Thanks again for your help
    John

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