The Hopzooka: Continuous Hopping Behemoth

I love beer.  I love many types of beer.  Bring them on: malty, roasty, smokey, funky, hoppy…they’re all awesome – providing they’re well made.  One of my favourite commercial beers is Dogfish Head’s 90 Minute Imperial IPA: a great balance of maltiness and insane hopping.  If you’re familiar with this brew, you know that they hype their ‘continuous hopping’ method as a reason for this beer’s awesomeness.

I was reading Brew Your Own magazine’s Hop Lover’s Guide last year, and I saw a project to build a continuous hopping device.  I liked what I saw, as it was a way to fiddle in the garage and make something that would look impressive and – possibly – make awesome craft beer.  Not ever being content with simply replicating what other people do, I saw some ways I wanted to improve on the design and make something that would inspire awe in brewers and terror in boil kettles.  Cue evil, maniacal laughter…NOW.

I decided on a cylindrical delivery device powered by a one RPM motor, which I would mount on a large camera tripod.  There were different options available for the cylinder, such as cheap and easily-accessible PVC pipe.  The problem with PVC is that you can’t see what’s inside, and I think that takes the fun out of it, to be honest with you.  I found a supplier (Laird Plastics) that had clear acrylic cylinders.  I ordered six feet of four inch diameter pipe.  Not that I needed six feet, but it was the smallest length they stock.  This would provide me with a relatively resilient delivery system that would allow me to see the internal operation of my hopping unit.  I cut a two-foot length of the pipe and prepared for some real work.

On the back of the pipe, I attached a white PVC female fitting, into which I screwed a male end cap.  On the cap, I bolted a one RPM motor that I picked up from Acklands-Grainger (just Grainger in the U.S.).  To the motor, I wired an electrical plug, which I planned to plug into a switch, which would then go to an small extension cord.  I did this, rather than just wiring the motor directly to the switch, because I wanted to secure the switch to the tripod, so it wouldn’t swing around.  I also wanted to be able to remove the cylinder from the tripod for storage.  There you go.

I attached a 3/8 inch threaded shaft to the motor- just a bit longer than the pipe.  This would create a sweet shaft going down the middle of the unit (yeah, that’s right).  To do this, I used a drill press to make a hole in the short shaft coming out of the motor, as well as a hole through a 3/8 ID threaded coupler.  I used a bolt to attach the coupler to the motor shaft, and then threaded the long 3/8 shaft into the coupler, securing it with some Loctite.

I drilled a hole in the middle of another PVC end cap; I wanted this cap to be able to spin on the end of the tube, powered by the slow rotation of the motor.  Now, the inner diameter of the cap was just a little larger than the outer diameter of my pipe; to get around this, I used some aluminum tape (that you use on heating ducts, etc.) and wrapped it around the end of the pipe several times, boosting its outer diameter to the point where it created a decent seal and didn’t wobble, while still easily rotating…all smooth and sexy.

In the bottom end cap, I drilled a rectangular hole.  This was to be the outlet for the hop pellets.  I started small, intending to increase the size as necessary to ensure an adequate dropping of pellets from the chamber.  I also drilled four small holes close to the perimeter of the cap.  I then inserted small diameter, 1.5 inch bolts and secured them with locknuts.  This would help prevent the hop pellets from bunching near the outlet.  If they tried, the bolts would bring the pain.

I threw a wing nut on the outside of the cap and called it a day.  Or, so I thought.  Balls.  When I turned it on to watch the movement, I noticed the bottom end cap slowly unwinding from the threaded shaft.  I thought adding a locknut to the shaft would help.  That didn’t work.  After some head scratching, I drilled another hole in the cap, about an inch from centre, and added another bolt, which I attached to the main shaft (on the inside – it looked better that way!) via some random, short piece of metal that had two holes drilled in it.  I then attached this ‘security’ bolt with a locknut.  Between the threaded shaft and the security bolt, the cap decided it didn’t have the testicular fortitude to mess with me further.

I cut a large hole near the top of the unit – what fun…using a hole saw to cut the outside of a cylinder.   This would be my hopper, as it were, allowing me to load the unit with hop goodness.  To my make life easier, I cut the tip off a small funnel and, when ready to load, hold in on the unit and pour away.  I originally attached it to the pipe with silicone, but one good knock (after a few homebrews) took it off.  I decided to scrap the idea of the attached funnel…I can just put it in place when I need it.  To finish off the cylinder, I also took the plastic bracket from the camera tripod and bolted it to the pipe.  Doing so would allow me to easily attach and detach the pipe from the tripod.  It’s all about making life easy – storage included.

It was now time to test with hops to check the drop rate.  I found I needed to drill the outlet a bit larger…no big deal.  Also, when I added hop pellets, I found it wise to break any extraordinarily large ones in half, so as to reduce the possibility of jamming or refusing to take the plunge through the hole.  It only takes a second to pick through the hops, so stop looking at me like that.  The final issue was to actually determine the hop rate.  Easy?  No.  This meant a few hours of my time…and many beers to make it entertaining.  I loaded up the hopper and set it above my digital scale.  I spent the next while checking the added weight of hops every 10 minutes, which averaged out at a fairly reliable 24 grams.  I decided on 10 minute increments, as I didn’t want to sit there with my brewing software, entering hop additions for every freaking minute.  I thought every ten minutes was accurate enough, especially considering this would only be used for highly hopped beers, where the utilization and IBU calculations are sketchy, at best.  It comes down to a matter of sheer hop flavour and aroma, not bitterness levels.  Furthermore, the gentleman in the article I had read had also decided on 10 minute calculation increments for his device, so I went with the flow.

So, there you have it.  I christened this beast the Hopzooka and went to show my wife, as she had given me the cash to build it as part of a birthday present.  I proudly turned it on and pointed out how the cap was slowly (painfully slowly) turning.  She looked at me with amazement and then asked, “that’s what you built?  Are you kidding me?”  Well, we can’t all be brewing geeks.

When I told this story to a non-brewing friend of mine, his response was, “well, that’s great!  You’ll be able to set it up and go spend time with your family, since you don’t have to sit there and add hops every few seconds.”  I looked at him like he was crazy.  As if I’m going to go to the trouble of building this monster and then not sit there and enjoy watching it every second it’s in operation!  Some people just don’t get it…