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JackH
OfflineAdmin
· 07/04/2020 10:27 AM
Happy 4th of July! jazzyhands

JackH
OfflineAdmin
· 06/24/2020 7:58 AM
@Mark McCornack, Please post your question in the forum.

Mark McCornack
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· 06/15/2020 9:28 PM
Hi! Looking for a legacy inlet temp sensor on 13 yr old Gene Cafe. It seems they've changed it and now you need new mother board and new sensor. Any ideas where I can find compatibile old one? Mark

Samaniego
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· 06/09/2020 6:39 PM
Wich thermometers Can i buy for my roasting machine compatible with usb or macbook?

JackH
OfflineAdmin
· 06/05/2020 5:38 PM
peveleth, It is better if you start a post in the forum with your question. These shouts go away in time.

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1 lb drum build
Scooter75
Hello everyone,

Been roasting on a kkto for the last 2 years that I built my self.
Wanted to step up to something new. Thought about buying a drum roaster, but decided to do it my self.

So, I am starting on a 1 pound drum build.

I have a workshop and tools and I am a mechanic by trade. So not afraid of the process just have some questions along the way.

So here is the first problem I am having.

I am lost on the vane helical angle. I need more information on how to calculate the vanes.

Tried putting the data into the calculator that is linked here but I am having problems understanding the numbers that come out and not sure I am putting in what I need to.

Here is what I got.

Drum is 6.5" deep, outer diameter is 6.625, inner diameter is 6.357.
It seems the preferred angle here is 20 degrees.

So how do I use this data to calculate my vanes?

Thank you,

Christian
 
Scooter75
I forgot to mention that it will be 3 vanes.

Already did the Fab on the drum spiders.
 
renatoa
Why do you think a drum will roast better than a kkto ?
Especially when no increase in load, 1 lb is kkto sweet spot.
The heat transfer in a drum is a mess... starting with vanes design, then airflow management... what benefit ?
 
Scooter75
I don't know if a drum will or will not be better for me. Just wanted to try something different and thought I would build a drum roaster.

My kkto does 340 grams pretty well. A pound is ok.

Wanted to try something new. If it is good then great, if it is bad then I wasted some time and a little money, had fun and hopefully learned something in the process.

Just looking for a little help along the way to make it it best I can, and right now I need some help in figuring out the vane geometry.
 
JackH
I am a KKTO user too and always wanted a drum roaster. Welding is the stopping point for me.

There are others here who have built their own drum roasters and hopefully should help answer some of your questions. Have you looked around at some of the builds in the drum roaster section of the forums?

Allen posted some drum calculators here: https://forum.homeroasters.org/forum/...ad_id=4645
---Jack

KKTO Roaster.
 
Scooter75
Hello Jack,

I have been reading the drum roaster discussions and that is what inspired me to build one.

Been around different internet forums for awhile and know that doing a search of the forum is one of the first recommendations. I have found the vane calculator and down loaded it. The math isn't hard just trying to determine what value to use for the P variable in the equation and what this 20 degrees that keeps being mentioned in the posts that I have found with any mention of fabricating vanes.

Christian
 
renatoa
A drum can be built without welding, there is riveting that works as well.
But heat exchange during a roasting is a mess compared with the clean convection that happens in a TO... experienced drum roast at a pro facility of a friend, and was enough to decide is not for me.
 
CharcoalRoaster
Renatoa -- then what is the solution for increased batch size as the OP desires? If KKTO caps out at 1lb then what's the next step in order to meet load desire/need?
 
renatoa
In the initial post, as I read "step up" does not mean more load, he want 1 lb drum.
TO based builds are able even of 800 grams, from others experience, 650 grams from mine, so there is enough margin.
And even there someone can push more... adding a second element as a spiral in the bottom, under roasting pan, or additional tubes in the lid, 1kg is easily doable in a 5-6 quarts pots.
So there, at 1 kg, is where I see the limits of a TO based on the commercial glass lid, but not the principle itself, scaling up the convection unit can be done, but I see easier to add a second unit than building a 2 kg capable TO from the scratch.
There is at least one example of a guy roasting professionally, with such dual setup, and he is is not a DJ Grin
Doubling the capacity of a drum is not that easy, is a total rebuild.
 
allenb
Scooter 75 wrote:

Quote

I am lost on the vane helical angle. I need more information on how to calculate the vanes.

Tried putting the data into the calculator that is linked here but I am having problems understanding the numbers that come out and not sure I am putting in what I need to.



I agree that the arc calculator is a pain and not easy to navigate. I've since found it easier to just cut poster board paper arcs until you find the arc that makes perfect contact at the desired angle. For a marking template, I place a thin (1/8") piece of wood on the bench with stops on each end of it and push the middle into an arc at different measured distances of deflection with the poster board underneath and trace a pencil mark on it and cut out with scissors. Once you get close, it won't take many attempts and for vane angle placement, go for anything between 20 and 30 degrees.

The reason for not making the angle 45 degrees is I found there to be too much piling up of beans at the front plate keeping the rest of the drum from effectively sharing in heat transfer. This was noticed even with a good set of reverse vanes. I don't think this is as much of a problem with larger shop roasters.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Scooter75
Allenb,

Thank you, I understand the tool you describe to get the arc.

Just wanted to verify I understand the vane angle.

That is the angle the vane would rise from front to back of the drum. Am I correct?

Next question,
How wide should the vane be, is there a ratio to drum diameter or some other sizing requirement?

Christian
 
allenb
Let's say you drew a straight pencil line on the inside drum surface from the front of the drum back to the rear and we can call this 0 degrees. Now draw a line at an angle greater than 0 degrees, let's say 25 degrees and this is the angle we're talking about.

On vane width or vane height for a drum diameter typically used for a 1 lb drum, I would go with a 1" vane for a 4 vane drum, for a 3 vane drum I would go 1/8" wider to add some additional agitation and lift.

I don't know of any articles or charts covering vane design for coffee roasters but am basing this off of experience and seeing other commercially made roasters.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Scooter75
That is what I thought for the angle after reading your last post.

I made a template today after talking to a couple of engineers at work. It was close. Used your method to fine tune it. I have a good template to cut some vanes now.

Thank you, your information has been very helpful to me!
 
renatoa
The shortest path between any two points on a curved surface is called a geodesic, this is the term that you should use in searches to find how to design a vane.
The result of such search would list articles as below:
https://www.gregschool.org/articles-p...nder-mley2
Edited by allenb on 12/11/2019 8:15 PM
 
allenb

Quote

Scooter75 wrote:

That is what I thought for the angle after reading your last post.

I made a template today after talking to a couple of engineers at work. It was close. Used your method to fine tune it. I have a good template to cut some vanes now.

Thank you, your information has been very helpful to me!


You're welcome, glad to help! It's always good to have some engineering folks at work that we can bounce things off of when we hit a wall so to speak. I worked for Lockheed for a few years and was always able to get quick answers whether the issue be in electronics or mechanical engineering although sometimes the answer to my questions was in a language too complicated for my more basic engineering skill set.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb

Quote

The shortest path between any two points on a curved surface is called a geodesic, this is the term that you should use in searches to find how to design a vane.
The result of such search would list articles as below:
https://www.gregs...nder-mley2


Hi Ren,
After watching the video I think I'm now equipped to be able to handle space-time continuum and black hole gravity calculations but not sure if I'll be able to pull off the radius of helix.
What would be great would be for someone with good higher level math skills to reduce the equations to an extremely simple formula where we enter inside the drum radius of circle and pitch angle and it spits out our arc radius. I'll do some searches using the geodesic term and see what comes up.
Edited by allenb on 12/11/2019 8:17 PM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Scooter75
Hello.

It's been awhile so I thought I would post a few pics of my progress.

Drum done, burner built(sorry no pics of that, but used Allen's slotted tube and instead of a torch, I used a drilled out jet burner), endplates pretty much done, inner shield about 75%(no pics),
Bearings and motor mounted,

I am pretty bad about taking pictures as I go, so these are from my work today.
 
Scooter75
Forgot to attach them!
 
Scooter75
One more try, hopefully they make it here!
 
JackH
Be sure to keep the photo filename simple with no spaces or special characters. Jpg, jpeg,gif,png are supported. Max file size of 10Mb.

Don't use the Preview post button, they will never load correctly.
---Jack

KKTO Roaster.
 
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