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Gigimedrano
04/17/2019 6:33 AM
Hi guys, my hot top has stripper a gear.. ive only had it for a lil over a year now hot top wants 120+ for a new motor and gearbox assembly any idea? Is this normal year and some Months dont seem lik

Ray Kahuna
04/16/2019 8:04 AM
has anyone built an adjustable coffee grind press?

Nitesh
04/01/2019 10:04 PM
Hello, I have been trying to get in contact with manufacturer of HB roaster in China but failed until now. Does anyone have idea who is the manufacturer of HB roaster in China?

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03/30/2019 3:46 AM
Spammer babble from me and others have been removed from Centrifugal Roasters Thread. From here on we will toss them immediately. ThumbsUp

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Optimum bean tumbling
oldgrumpus
I'm sure this must have been discussed somewhere, so maybe I just missed it. Looking at the video of my junk bean test it seems that the drum is not rotating fast enough to reach a tryer if installed in the usual position around the 4 o'clock position. Should beans become airborne as they near the top of the drum and free-fall on the other side? Is there a video somewhere that shows the "perfect" speed with beans visible?

Here's the photo album that contains my beans in a rotating drum: https://goo.gl/ph...QBepy2Ka16

Thanks y'all!
Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
Koffee Kosmo
Drum speed depends on a few factors
But the rule of thumb is - 45 rpm to 60 rpm

What's actually needed is for the beans to be constantly in motion always rolling and mixing at the same time

KK
I home roast and I like it
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: Mazzer Robur Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
http://koffeekosmo.com.au
allenb
Should beans become airborne as they near the top of the drum and free-fall on the other side?


Yes, airborne is the rule with all commercial drum roasters. Shoot for the beans to land somewhere around the bottom center of the drum or a little beyond center. This not only provides a means for convection heat transfer to occur but is a necessity for adequate chaff separation in a drum roaster. Also, as you stated, allows the trier to grab the beans.

I would shoot for around 65 rpm to be in the ballpark.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
oldgrumpus
Well that is reassuring. I thought the target was about 50rpm and wondered what went wrong. Is there any benefit to using variable speed control? Seems like when the magic speed is found there would be no benefit.
Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
allenb
I have heard reports from some using variable drum speed, of differences in the cup related to using different speeds but I've never heard of any studies using blind taste tests to back it up.

My own experience, as long as neither too slow or too fast extremes are used, is that there would only be minuscule cup differences noticed only by some of the most gifted super-tasters out there. I've never noticed any difference.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
oldgrumpus
I'm back after taking a long hiatus from my project. Now working in-earnest to finish it. I uploaded a new video to YouTube of an experiment on my drum roaster using junk beans. With a full load of 3 lbs, I gradually increase the drum speed to see how the pattern of tumbling changes. It's a very fine line between maximum tumbling and centrifugal force winning by sticking the beans to the drum wall, which can be seen for a brief moment at the end of the video. Sorry I did not keep the camera going longer. I saw it coming and went to turn off the motor not thinking this might be an instructive moment for others!


Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
Stew
Glad your back at it. Life has a way of getting in the way of fun sometimes :)
What RPM did the video start at and then end at?
 
oldgrumpus
The previous video started around 50 rpm and ended at about 80? rpm. I've done another video today where the rpm is constant and, I think, at the ideal rpm. I'm unsure of the exact rpm, but I think it's 82. You can count revs by slowing the video down to .25 playback speed. I'd appreciate a second opinion on the number.


Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
Stew
I counted 42 in 32sec so 41 in 30 = 82 Should be pretty close.
Do you have a picture of the inside you would share? I'm fitting veins/paddles (what ever there called) to my roaster build right now and I keep second guessing my design. Curious how you handled it.
 
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renatoa
Wondering how an accurate BT reading can be done with such tumbling...
You are close to fluid bed there Grin
 
oldgrumpus
https://get.googl...pu2gjKLgAw

Let me know if the link doesn’t work. I will post photo of inside of drum if link doesn’t work. Basically I tried to copy what was done in a Diedrich roaster, but of-course... on a smaller scale! Grin
Edited by oldgrumpus on 12/31/2018 3:44 AM
Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
JackH
Your link works! Very nice work on the roaster.
Always wanted a drum roaster.
---Jack

KKTO Roaster.
 
oldgrumpus
renatoa wrote:

Wondering how an accurate BT reading can be done with such tumbling...
You are close to fluid bed there Grin


Do you think that the tumbling is too aggressive? I haven't thought about it. Maybe it is!?
Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
renatoa
Your video should make thinking again those claiming there is heat transfer by conduction in a drum roasting Grin
 
oldgrumpus
Well, only if it spins near maximum. The videos showing slower rotation do show more prolonged contact with the drum... I think spinning this fast is unusual.
Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
Stew
Very nicely done!
How many pounds are you using in your last video? It appears to be a bigger roaster than 3lbs from your original thread. But looks can be deceiving.

Stew
 
oldgrumpus
There are 3 lbs of green beans in the drum. It looks more full since the vanes are pulling the beans forward. The rearward movement provided by the reverse vanes is not as effective as I hoped. Will leave it for now, but if it doesn't perform, I may have to reconfigure them.
Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
Stew
You've peaked my curiosity. The wisdom here, that I have no reason to dispute, is vol/10=oz or 166 in3/lb. In your original thread your drum was 10 1/4"ID x 15" or 1223 in3 which should give you a capacity of 6.3 - 7 lbs depending on which formula you use. The video makes 3 lbs look like a very full load. Does it seem that way to you when your able to see it in real life?
I'm curious because the drum I have on the go right now is the same diameter but shorter (9 1/2") and I was hoping for 4 1/2-5 lbs. Not going to change my drum now but it would affect the size of hopper I need.
One question I've had with regard to the formula: Does it calculate max load or closer to the sweet spot? North Roasters claim actual roast capacity and there 2kg is 535 in3 and there 3kg is 1211 in3 though they both have slightly different length to diameter dynamics.
 
oldgrumpus
Stew wrote:

Does it seem that way to you when your able to see it in real life?

One question I've had with regard to the formula: Does it calculate max load or closer to the sweet spot?


Stew, these are great questions! The answer to the first (about the video and does it look that way in real life) is, yes, it does look that way. But that's not the full answer. Keep in mind that the vanes are pulling the beans forward toward the camera. The rest of the drum doesn't look anywhere near that full. That being said, some things for me to consider...

Would it be better to slow the drum down? If so, the beans will have a hard time reaching the tryer on the right side! another issue is that a slower speed will create a more dense mass of beans that will likely take a bit longer to heat up (my theory with no supporting evidence :-) ).

With regards to your next question, I don't think if have the answer. Sorry, I'm not that informed :-(
Espresso: Franke Ecolino
Grinder: Macap M4
Roaster: Old fire extinguisher with a crank, over a crab cooker, now building a drum roaster.
 
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