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Double Barrel Blending Roaster
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| Lylabrown |
Posted on 04/20/2012 00:11
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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I've discovered the need for a small batch roaster. Doing small (1/4#) batches in my 1# roaster for blends is not very efficient. And changes the roasting dynamics considerably. A single drum would do, but why stop there, why not build a double drum?
Also, we have another 2 months of dark rainy days here in the Northwest. For sanity's sake - I need a project. Here's what I have in mind. (click for larger view)
The two outer shells will be cube shaped with open walls on the bottom (for chaff removal) and the inside (nearest to the nichrome coils). The two sides pivot independently of each other for pinpointing the optimal dump time for a particular bean. A chain drive in the rear powers the drums. I'd like to have the drums rotate in opposite directions to keep the beans as far from the heating coils as possible to prevent scorching. Small 1 to 1 ratio gears can be added to one of the drums to reverse its rotation.
That's the concept so far.
Russ |
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| ajrunningbiking |
Posted on 04/20/2012 06:49
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Newbie
Posts: 14
Joined: 11/17/2011 19:57
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Can't wait to see this build project progress!!! What an awesome concept! |
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| Dan |
Posted on 04/20/2012 09:55
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Founder - Member
Posts: 1798
Joined: 10/24/2005 17:09
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Using a chain as a rack is a novel idea. Here's a suggestion: The motor is located at the point of greatest chain flex, which means it could skip teeth. Instead, direct drive one of the end sprockets with the motor. It will eliminate any skipping, and save you the price of one sprocket.
Traditionally, as you may know, sample roaster drums are driven with a worm and worm gear arrangement, which allows disconnection like the sprockets you have. The advantage for you is that this makes it easy to reverse direction of one drum provided you can find both left and right worms and worm gears. Try smallparts.com
Alternatively, you could direct drive both drums with individual gearmotors in the same way my sample roaster is driven. The cost of these little gearmotors could very well be cheaper than chains and sprockets. The trick will be finding CW and CCW gearmotors since those shaded-pole motors are not reversible.
http://www.claycr...oaster.htm |
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| allenb |
Posted on 04/20/2012 10:07
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Super Admin
Fix It Man
Posts: 1473
Joined: 02/23/2010 19:51
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Dan,
Merkle Korff offers reversible. I used them for the gearmotor for my 1/2 lb'r. They can custom configure it for you to take up less of a footprint also. Great company!
http://merklekorf...tors/8134?
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| Lylabrown |
Posted on 04/20/2012 10:49
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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You are correct. While it might be more fun to engineer a chain drive, It would more than likely be a total headache to implement it. Simpler is usually better. I'll go with a couple of these little DC gearmotors instead. http://www.surplu...e=electric
That simplifies things considerably while also decreasing the size of the base.
As you can see here:
I'll start scrounging around for parts this weekend.
Russ |
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| Dan |
Posted on 04/20/2012 11:16
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Founder - Member
Posts: 1798
Joined: 10/24/2005 17:09
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That looks like your best bet. They have plenty of torque. It also has the advantage of supporting the rear of the drum, too. |
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| Lylabrown |
Posted on 04/21/2012 17:48
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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Hand Towel Dispenser + Bread Pan + Film Canisters + Martini Shakers = Roaster
I wanted to do more of the fabrication myself. Oh well. |
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| Dan |
Posted on 04/22/2012 06:06
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Founder - Member
Posts: 1798
Joined: 10/24/2005 17:09
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Why stop at just two barrels! |
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| Lylabrown |
Posted on 04/22/2012 08:33
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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You asked for it Dan!
A quad drum roaster! |
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| Lylabrown |
Posted on 04/23/2012 09:41
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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Is that what you had in mind?
After considering the various problems the design will pose...It's settled, I'll build it.
I like the idea of having an all-in-one roaster that can roast multiple bean varieties individually. Although they'll all have same time/temp profile, having control of the roast level of each particular bean is more important.
Would you like updates? Or just highlights/problems?
Russ |
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| RoasterRob |
Posted on 04/24/2012 02:50
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1/2 Pounder
Posts: 318
Joined: 03/03/2007 22:30
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For those who have seen this article before on CS.
http://coffeesnob...040424/100
JMO but the coolest looking sample roaster. If I was going to build a multi barrel sample roaster I would try and build a copy of this Gothot. Also made in 5 barrel format.
Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
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| Dan |
Posted on 04/24/2012 04:56
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Founder - Member
Posts: 1798
Joined: 10/24/2005 17:09
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Russ, I was imagining four barrels in a row because your design requires them in pairs since they share a heating element. |
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| Lylabrown |
Posted on 04/24/2012 17:17
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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Rob - What an epic thread! The roaster is a beauty and a beast.
Dan - I considered that as well. It morphed into the current design from there.
Made a full size cardboard mock-up:
I'm happy with the aesthetics. For the shell I'd like to use aluminium sheet that's constructed like cardboard - not sure what it's called. It might be out of my price range though. Otherwise plain aluminium sheet will do.
In the bottom image you can see how the interior is mostly open between the upper and lower shells. Which essentially makes it one chamber instead of four. The trick will be locating the nichrome heating coils for optimal heating of all the drums. I'm guessing two will be located between the upper /lower drums, and another two on the sidewall of the lower shell.
Look okay? |
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| Dan |
Posted on 04/24/2012 17:32
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Founder - Member
Posts: 1798
Joined: 10/24/2005 17:09
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Russ, I think you are trying too hard to make a universal machine. I'm concerned that you will have problem with getting enough heat up to the top three barrels. And, dumping the large barrel is going to take more effort because of the weight of the extra barrels on top. Here's an idea based on my prediction that you won't be using all four barrels at once. Why not make a convertible machine?
Keep the lower heating chamber and controls just the same. Then, make up two roasting "tops" for it. One has the large barrel and will be a lot like my one pound sample roaster. When you want to try some blends using smaller batches, take off the large barrel and drop on the three little barrels. |
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| Lylabrown |
Posted on 04/24/2012 18:48
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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Appreciate your input Dan. A more modular design sounds neat.
I share your concern about the upper barrels not getting enough heat.
As a remedy I considered having two separate sets of 1200w nichrome coils. One for the main barrel, and another directly underneath the smaller ones. Which wouldn't be run simultaneously. The controls would be all the same except the SSR output line would have a switch to toggle between the upper/lower coils. Creating two machines in one. Essentially what you suggest, except keeping the current design intact.
As you can tell - I'm a little attached to my current design.
In the end...I concede. Your modular idea is better. Two individual tops sharing a common base makes a lot of sense. They can be optimized better that way.
Back to the drawing board. |
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| Lylabrown |
Posted on 04/25/2012 10:18
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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I think we're on to something here. Dan's "convertible" roaster idea is a brilliant one.
It makes for a multi-purpose platform that's not only useful for roasting, but also food dehydration, sausage fermenting (another hobby of mine), Etc, All one needs to do is fabricate another "top" for that particular function.
I think we're at version 4.0 of the design now:
The two "tops" can be attached/hinged by a simple sliding latches on the front face.
There will be plug-in sockets for the motors on the side of the base. One each for A/C + D/C power supply for the motors, with a DPST switch to control both. The sockets can be two different types to prevent any mix-ups.
I'm excited! |
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| Dan |
Posted on 04/25/2012 10:43
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Founder - Member
Posts: 1798
Joined: 10/24/2005 17:09
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WORKS FOR ME! |
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| Lawnmowerman |
Posted on 04/26/2012 13:53
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1/2 Pounder
Posts: 291
Joined: 03/14/2012 15:21
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Are we talking about running any two drums simultaneously? Wouldrequire a lot of skill. What if 1 drum hits a stall? But not the other and they share the same heat?
Bad coffee prevails when good coffee roasters stand by and do nothing.
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| Lylabrown |
Posted on 04/26/2012 17:08
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1/4 Pounder
Posts: 107
Joined: 02/15/2012 22:00
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Three drums. In my experience with "pre-blends" the beans follow roughly the same profile from drying phase all the way to 2nd crack. Some may take a little longer than others, but usually finish within 1 or 2 minutes of the rest. The goal with this roaster is to have control over the final roast level of each bean variety. Independent profile control would be nice, but it's not practical at this point.
Did more material scavenging:
Found the 3rd and final martini shaker at the local goodwill store. Also got a great deal on 16ga galv. sheet. It's a bit heavy, but what the heck, It'll be much more robust than my current roaster, which is a little too flimsy for my liking.
While imagining the final look when sheathed in galvanised steel - This came to mind:
We may have to get creative to conceal the "concrete blockyness" of it. |
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| Dan |
Posted on 04/26/2012 17:58
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Founder - Member
Posts: 1798
Joined: 10/24/2005 17:09
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I like the constructivist look!
Running multiple sample roaster barrels is common practice in cupping rooms and some have more than 3 barrels. Sure it will keep you hopping, but it shouldn't be a problem. My experience with my sample roaster is that I rarely have a stall and it usually because I'm not paying attention during a manual roast. With a PID profile roast it never stalls. |
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thanks for joining.
for you