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Larry Cotton's 'wobble disc' heat gun build
mtbizzle
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Posted on 07/16/2020 10:33 AM
See here - https://www.youtu...=emb_title
Roast: Kaldi wide, SR800 + projects
Grind: Lab sweet, Bentwood, giota w/ MP burrs, Commandante
Pull: Decent, La Pavoni, Elektra Microcasa a Leva, Faemina anno 60, Kim Express
 
renatoa
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Posted on 07/17/2020 2:33 AM
The beauty of the simple design... ThumbsUp
Got inspired to try one day this idea using a reversed TO as source of heat. Grin

Wondering why not cooling in the same machine, just cut the power, and let the airflow blow...
 
lmc
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Posted on 07/23/2020 3:31 PM
the Harbor Freight heat gun i used does not have a blow only function, so cooling must be done (immediately after roasting) by other means. i use a small screen tray with a fan below.
 
Brandon
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Posted on 07/27/2020 10:19 PM
I love this design. It's really clever.
 
renatoa
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Posted on 09/21/2021 3:35 AM
The wobble disc is borrowed by others for their own designs... also very elaborated, but not so simple and clean as Larry's.
 
Koffee Kosmo
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Posted on 09/22/2021 5:45 PM
I like the Drogo roaster - great design application ?

KK
I home roast and I like it. Designer of the KKTO
Roaster Build information
https://homeroast...ad_id=1142

https://docs.goog...lide=id.i0
Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
 
Web
CharcoalRoaster
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Posted on 09/23/2021 8:58 AM
cool

wobble disc very innovative
 
allenb
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Posted on 09/23/2021 9:06 AM
Great design and execution!!!

Could this also be equipped with IR lamps on top?
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
CharcoalRoaster
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Posted on 09/23/2021 9:58 AM
Additional question... could the wobble disc be driven/adapted vertically (from the bottom) instead of horizontally (from the side)?
 
renatoa
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Posted on 09/23/2021 11:30 AM
... could be, but the agitation will be different, and worse than horizontal.
Will get just a peripheral stir, without the alternate flipping of the layers you have when disc wobbles as in Gene/Larry design.
Also, for vertical case the paddle should match perfectly the same curvature as the bottom, else some layers of beans could stay still in the same place on the bottom for the whole roast process, and get burned more than superior layers.

If you want a vertical placement for the agitator, then rather evaluate an Archimede screw design, as in Nesco.
 
CharcoalRoaster
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Posted on 09/24/2021 6:58 AM
Which is actually why I was asking Ren -- my auger design failed miserably as the auger I had wasn't large enough to provide decent agitation even at high speeds (110rpm).
 
renatoa
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Posted on 09/24/2021 9:16 AM
You can simulate the vertical design of wobble disk with a pencil stuck in a cardboard disc, fixed at an angle with hot glue, then drop some beans into a cylindrical cup and rotate with fingers.
Not Kansas, definitely...
 
renatoa
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Posted on 12/04/2021 2:02 AM
Another great design of Larry C Grin

https://makezine....a-machine/

... it's quite old, wondering how nobody noticed it so far...
 
allenb
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Posted on 12/04/2021 6:01 AM
Nice! Would be compact enough for taking camping. He's made some real nice designs using strainers since getting his start in roasting machines.

I didn't realize he was a professional tool designer but now his designs makes more sense.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
wbbh
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Posted on 12/04/2021 7:26 AM
I was inspired by Larry Cotten to build a similar roaster. I used his previous design that uses a smaller set of paddles. In the video below the roaster is working, but in a sort of prototype stage. The foil extension was replaced with a section of flashing.

because my paddles were made from the cover of an old hard drive it was not exactly flat the paddles shifted on the shaft. It was serendipity because the angled paddles allow me to roast up to one pound of coffee. The battery operated screwdriver is marginally strong enough to do one pound and it is happier with a little less. I quit working on this roaster when I got my fluid bed roaster finished.
 
allenb
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Posted on 12/04/2021 8:41 AM
Looks like even the more primitive version worked real nice!

If you get a moment, please shoot an update in your fluidbed build thread on how it's coming along.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
wbbh
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Posted on 12/05/2021 9:22 AM

Quote

allenb wrote:

Looks like even the more primitive version worked real nice!

If you get a moment, please shoot an update in your fluidbed build thread on how it's coming along.


It's working well, it can handle a two pounds, but usually roast 800 grams. I recently added a vernier drive to the sped control to get more subtle changes to fan speed and to keep the f-wit running the roaster from accidently blowing beans out the top or turning the fan flow so low it scorches the beans in the bottom of the roaster.



This is a post here about the roaster build: https://homeroast...post_73712

I added a parts list to the original post.
Edited by renatoa on 12/05/2021 9:46 AM
 
allenb
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Posted on 12/06/2021 9:04 AM
Looking nice! Great bean movement with your build. Keep us updated with any new news.

Happy Roasting! christmas tree
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
CharcoalRoaster
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Posted on 12/06/2021 2:39 PM
Is that a bake-a-round for the RC or something custom? I have a FB roaster that could probably handle 2lb but was too afraid of blowing beans out of the top toward the end of the roast.

Do you have some kind of perf plate on top to keep your beans in or do you just control airflow really carefully?
 
CharcoalRoaster
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Posted on 12/06/2021 8:05 PM
WBBH cool

Thanks to your inspiration I pushed my FB roaster to 800g tonight and it performed wonderfully. I was always too afraid of shooting beans through the chaff collector but I didn't lose a single bean was able to determine that my heating element can handle up to 1000g minimum most likely.

rockon
 
wbbh
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Posted on 12/07/2021 7:45 AM
^^^ Excellent!
 
Ploni
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Posted on 12/10/2021 1:23 AM
I've been intrigued by Larry Cotton's Wobble Roaster which utilizes a heat gun as its heat source. Now I see he has a "wobble" device for a grill so I'm thinking it might be an efficient solution to use with my very effective electric cooking device.

I've recorded temps on this cooking unit of over 460°F/238°C.

That is hot enough, correct?

What do you think of the idea of mounting Larry's grill wobble device on my electric cooking unit (see photos below)?
Ploni attached the following images:
wobbleadapt_2.jpg electriccookunit_2.jpg
Edited by Ploni on 12/10/2021 6:01 AM
 
timbarnes
Top  #23 Print Post
Posted on 12/11/2021 12:51 PM
It should work fine in terms of providing heat. I would want to monitor the element from time to time to be sure it's not overheating. I expect the designer intended for there to be fresh air circulating around the enclosure, so if you want to build this I would make the hood fit on top of the element, rather than sitting on the ground completely enclosing it. Also this will let you control the heat manually during the roast.

I roast 300g of beans in a wobble disk roaster with a 1500W heat gun and it seems to work fine.
 
Ploni
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Posted on 12/11/2021 3:17 PM
Thanks, Tim Barnes.

The heating unit is 1400W.

Do you think the wobble grill adapter should extend the full width of the heating surface (which I think is ceramic-glass)?

Would there be any benefit to removing the ceramic-glass to expose the heating coil?

Do you think a wobble device that I build should have a metal bottom like a tea kettle?
Edited by Ploni on 12/11/2021 3:24 PM
 
timbarnes
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Posted on 12/11/2021 6:45 PM
Well...some of these depend on your objective and approach to roasting and roasters.

For safety reasons I would not modify the burner unless there's a strong reason to do so. If you add a cylinder made from heating duct or aluminum flashing to the bottom of your flour sifter, it should sit nicely over the element. Then you can control the heat easily.

In fact, if you use an 8 cup flour sifter, you could simply stand it on the element. I have done this over a gas ring and it worked fine. That way you don't really need to break anything. You can hand wind it or add a motor as you prefer.

You don't want a metal bottom I think - better to have your heat source radiate directly to the beans. But you could try both ways. The DIY roaster experience is really one of experimentation, and I don't know how to predict the impact of a solid bottom, except to guess that it would increase thermal mass, and therefore make temperature changes slower. Is that something you think would benefit the roast?

I would suggest you try some options yourself, and report back as to what works and what does not.
 
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