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Taking home-roasting to the next level, need help!
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sversimo
Senior Member


Joined: 20 Jan 2010
Posts: 16
Location: Norway
Expertise: I love coffee

Espresso: Izzo Vivi PID
Grinder: Rancilio Rocky
Posted Tue Nov 20, 2012, 10:08am
Subject: Taking home-roasting to the next level, need help!
 

Hi, I have made my own coffee roaster- its an electrical drum roaster.

You can see the roaster in this video: Click Here (www.youtube.com)

But now I have decided to officially become a coffeegeek, and there is only one thing to do in order to become a true coffee geek,
write you master  thesis as a mechanical engineer about a coffee roaster of course!

I order to make the perfect roaster, I need help! And that's why I started this thread, I need all the ideas and as much feedback as I can get.

Perhaps there is something you are wondering about when it comes to roasting, and you would like an answer. Well, this is your chance!
I going to spend 20 week on just one topic, coffee roasting!
What is the biggest problem/drawback with coffee roasters today?
Whats good, and what can be improved?
What batch size should it cover, electrical, gas or both?


Depending on what i find out during my thesis, perhaps the perfect home roasting machine will be for sale in the future.


I'm thankful for every tip I can get, and will check in on this thread frequently
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frcn
Senior Member
frcn
Joined: 23 Dec 2001
Posts: 3,427
Location: Northern California
Expertise: Professional

Espresso: Vibiemme Domobar Double
Grinder: Mazzer Kony, Baratza...
Vac Pot: Hario, 2 Cory pots, 1 Cory...
Drip: Behmor Brazen, Bunn A10 mod...
Roaster: computer controlled Hottop,...
Posted Tue Nov 20, 2012, 11:51am
Subject: Re: Taking home-roasting to the next level, need help!
 

PLEASE put a grill guard over the chain drive. An exposed drive like that is quite dangerous. Ever see what is left of a hand looks like after being mangled by a chain drive?
The tryer needs a bit of work, and the addition of a counterweight to keep it upside down in the drum unless a sample is needed.
Placing the beans on a white surface will give a better idea of color.
No agitation arms in the cooling tray? It is why all cooling trays are round.

 
Visit My Website
www.EspressoMyEspresso.com
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oldgearhead
Senior Member
oldgearhead
Joined: 25 Jan 2010
Posts: 396
Location: Go Colts!
Expertise: I like coffee

Grinder: Virtuoso by Baratza
Drip: Chemex,Dilongi DCM900
Roaster: 1/2K Fluid-bed
Posted Sat Nov 24, 2012, 7:40am
Subject: Re: Taking home-roasting to the next level, need help!
 

Very nice! What was the total time and the wattage used in the 500g U-tube roast?
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sversimo
Senior Member


Joined: 20 Jan 2010
Posts: 16
Location: Norway
Expertise: I love coffee

Espresso: Izzo Vivi PID
Grinder: Rancilio Rocky
Posted Tue Nov 27, 2012, 12:18pm
Subject: Re: Taking home-roasting to the next level, need help!
 

Is that better? I mostly did it too check if the sound from the motor and chain would be reduced. The sound was lower, but not that much lower.

I believe the roast tok 18 min, not 100% sure.

The heating element is 2000W, but its connected to a PID, so its not easy to say.

sversimo: IMAG0144.jpg
(Click for larger image)
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Frost
Senior Member
Frost
Joined: 26 Jul 2007
Posts: 2,101
Location: Sierra
Expertise: I love coffee

Espresso: Isomac Venus
Grinder: Lelit PL53
Roaster: Poppery I w/variac, MET, BT
Posted Tue Nov 27, 2012, 8:53pm
Subject: Re: Taking home-roasting to the next level, need help!
 

The kind of things that would peak my interest in a home roaster taken to the next level:
Study the big pro commercial roasters and how they handle convection heating control.

  • Carefully designed air flow control that effectively gets the heat from the heating elements to the bean mass.

  • Controlled air flow that lets you maximize convection heating when you want it (during bulk heat ramp) like an air roaster, and minimize it when you want to coast through the finish, like a drum roaster. (both the Hottop and the Quest fall short in this measure)

  • Design the Drum with deep agitation fins that toss and tumble the beans, more aggresive agitation, for more even heating and better convection heat transfer. Maybe speed controlled to slow down when minimum convection is desired. (again; study how the big professional roasters do it, and shamelessly copy...)

  • If electric heating is used, careful design to maximize heater response, (minimum mass for this part, maybe nichrome elements).  likely some method of direct re-circulating of heat or heat exchanger will be needed.)

  • Insulate the roaster not just to improve efficiency, but to reduce the temperature gradients within the bean mass and roaster.

  • Good process instrument and control for temperature and air flow.

  • Keep roast times within the ideal range for the designed batch size. (1lb max is fine for a home roaster)

I realize it will be a challenge to accomplish all this while keeping costs reasonable.
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oldgearhead
Senior Member
oldgearhead
Joined: 25 Jan 2010
Posts: 396
Location: Go Colts!
Expertise: I like coffee

Grinder: Virtuoso by Baratza
Drip: Chemex,Dilongi DCM900
Roaster: 1/2K Fluid-bed
Posted Wed Nov 28, 2012, 10:06am
Subject: Re: Taking home-roasting to the next level, need help!
 

Frost here's a link to my $500, 120V, 500 gram, heat-recycling, stainless steel, fluid-bed roaster. It's made from an old air-pot brewer, a cocktail shaker,
a heat gun element and a vacuum cleaner motor..

Click Here (www.homeroasters.org)
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Frost
Senior Member
Frost
Joined: 26 Jul 2007
Posts: 2,101
Location: Sierra
Expertise: I love coffee

Espresso: Isomac Venus
Grinder: Lelit PL53
Roaster: Poppery I w/variac, MET, BT
Posted Wed Nov 28, 2012, 5:54pm
Subject: Re: Taking home-roasting to the next level, need help!
 

Thanks Jim, for the link.  I remember following your project & build a while back.  This is what we have to do to get what we want in a home roaster.

My ideal roaster would combine the benefit of both drum & air roaster, allowing full convection heating of an air roaster (for maximum ramp speed with minimum ET) and also be able to lower convection air flows when you don't want or need the heat transfer. (during finish when very little additional heat to the bean mass is needed)
I'm a die hard air roaster, and have trained to get great results,  but fluid bed requires the high air flow to agitate the beans for uniform heating even when you don't want or need that 100% convection heat transfer. I'm thinking mechanical bean agitation and full control of heated air flow volume through the bean mass.  
(I can accomplish this type of profile in my Poppery by turning way down on the air flow and stirring by hand,,, but yeah, that is a bit tiring; a carpal tunnel roaster if I roast too many batches)
I'm way overdue to build my roaster. Too many other projects.
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gregr
Senior Member


Joined: 6 Mar 2010
Posts: 210
Location: Los Angeles, Ca
Expertise: I love coffee

Espresso: Livia 90
Grinder: Moka
Drip: CCD
Roaster: Huky
Posted Thu Nov 29, 2012, 6:21pm
Subject: Re: Taking home-roasting to the next level, need help!
 

Bravo! Great job so far. You were a real coffee geek the second you started building that beauty ;-)
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sversimo
Senior Member


Joined: 20 Jan 2010
Posts: 16
Location: Norway
Expertise: I love coffee

Espresso: Izzo Vivi PID
Grinder: Rancilio Rocky
Posted Fri Dec 7, 2012, 3:19am
Subject: Re: Taking home-roasting to the next level, need help!
 

Thanks for all the great inputs!

Maybe two versions would be the best solution, that way I can make a high tech version!

There is probably something to learn from the professional roasters, but there is a huge difference between gas and electrical roasters.

I have thought about a smart way where basically all the warm parts of the machine works as a huge heat exchanger, preheating the air that will flow through the beans before they actually enters the machine. (where the air will be heated even more due to the airflow inside the machine)
There are more than one advantages to this

- No hot parts that you can burn yourself on
- Better efficiency
- Ambient temperature less important
- No water vapor or smoke will reenter the machine
- Better ratio between convection heat and conduction

Also i need to reduce the thickness of the inner drum, its 3mm thick. Its great if you have enough time to pre-heat the drum, but time is money
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farmroast
Senior Member
farmroast
Joined: 13 Jul 2006
Posts: 1,449
Location: Amherst MA.
Expertise: Professional

Espresso: Strega,Cremina, MCAL...
Grinder: Majors, Dienes
Vac Pot: Hellem10
Drip: CCD, and more
Roaster: 1kg. DreamRoast
Posted Sat Dec 8, 2012, 6:44am
Subject: Re: Taking home-roasting to the next level, need help!
 

Frost Said:

I'm thinking mechanical bean agitation and full control of heated air flow volume through the bean mass.

Posted November 28, 2012 link

This is the future. What I basically have designed into my roaster.
At a commercial level the Loring goes in this direction and the large probat centrifugal roaster.

 
Ed Bourgeois... LMWDP #167
please visit my blog
http://coffee-roasting.blogspot.com/
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