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Larry Cotton's 'wobble disc' heat gun build
Spyderman24-7
Top  #61 Print Post
Posted on 11/19/2023 2:14 AM

Quote

Piotrkurak wrote:

They supposed to spin that fast? Almost like a fluid bed.

I know Larry Cotton specified 100.rpm on the beater bars so you get about 400 agitations a minute but that looks more like 200 rpm


To each their own, but way too fast for my style of roasting. For my setup (sifter) I'm averaging around 84 rpm, but more importantly I go by visual. Too fast and heat is being lost and the coffee will be airborne too long to really absorb much heat... too slow and you risk scorching, so I dial mine in for a nice tumbling action so the bean mass really distributes the heat nicely.

I look for a specific type of sifter and have never had any issues getting most of them to function well in stock configuration, as in no need to modify the arms to get a nice sweeping action.
 
renatoa
Top  #62 Print Post
Posted on 11/19/2023 2:23 AM
+1 for the analysis above about speed.
Hard slapping a bean does not make it behave fluid... rather break
 
wbbh
Top  #63 Print Post
Posted on 11/19/2023 9:25 AM
Roasting more coffee helps, that was a first roast, since then the aluminum foil extension was replaced with sheet metal. I did get several good roasts for a frankly cobbled together project.

A switch to a variable seed screwdriver/gear motor would allow speed adjustments. That roaster was a bridge between the Hottop, visible in the video behind the home made roaster, and a larger fluid bed roaster I built. Before retiring the sifter roaster.

The biggest headache was the paddles slipping on the round shaft. Also clamping the screwdriver so it would remain still for an entire roast. I used a socket bit in the screwdriver to turn a nut on the end of the paddle shaft. This allowed me to easily lift out the sifter and drum the beans into my bean cooler.

See: https://homeroast...post_73709
 
enaskusuma
Top  #64 Print Post
Posted on 11/27/2024 7:04 AM
Dear all, hello there,

My name is Enas from Indonesia and I made a wobble disk roaster too but the beans got jammed
I need to know how much is the gap between the disk and the sieve of the sifter

thank you
 
renatoa
Top  #65 Print Post
Posted on 11/27/2024 10:00 AM
Related to gap, is important to specify if your beans support is rigid, made from perforated tin, or flexible, made from wires, like a sieve/mesh.
A flexible bottom could make easier to have beans stuck between agitator and the bottom.
 
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