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renatoa
05/23/2022 10:46 AM
abiy welcome cup

renatoa
05/18/2022 6:13 AM
gnosis coffee roasters and Terry Hauser, welcome !

allenb
05/15/2022 7:00 PM
lsawade welcome Welcome

renatoa
05/15/2022 9:13 AM
Welcome, Pinofly and Alex008

allenb
05/12/2022 7:47 PM
CafficitoeTim and pmf2000 Welcome! Welcome

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Another Bake Around Roaster and a New Member
keving
allenb - I will get video of the couple of roasts. I will also show my bean extraction system - idea provided my OGH but modified using things I had around house. Funny, I spent a few months working out the roaster design and about 10 minutes to slap together the extractor.

OGH, basically I played with only the exhaust of the roast chamber. The air delivery system going to the roast chamber is still sealed. I only estimated an 80% restriction - the top flange is hollow (upside down skillet) and it's top extends out to about 5" and about 90 - 95% of this flange was covered with a piece of plywood. - I will calculate this number more accurately for you if you like. But after the first 3 roasts I actually covered the entire flange with a square piece of 1/2" plywood about 9 X 9 inches and let the air pressure bleed between the top of the flange and the plywood - creating a slight back pressure in the chamber. There are 2 small holes in my flange where the handle was attached so air also bled from there as well, I liked this result the best and will try to replicate it with an oriface that can be placed into the flange which should be easy since I have no chaf collection system above the flange. If anyone is interested, I can run some tests with different sized oriface restrictions. Right now I am leaning towards the thought that more restriction is better than to little restriction.

One other thing that I noticed was an interesting effect with this roaster: At ambient temperature and at a set flow rate (just enough to loft the beans) once heat is applied, the flow rate increases. The amount by which that occurred was quite a surprise. I intend to look at some PVT info and figure out the expected air expansion at atmospheric conditions at various temperatures. I think that gas expansion caused this since the blower is running on a completely separate electrical circuit and that pretty much rules out any electrical spikes. Has anyone else seen this?
 
oldgearhead
1) Yes, you are absolutely right! The more you restrict the air exiting the RC, the hotter the bean mass becomes. I'm doing work in this area right now, and I have a warning:
NOTE:
If you are going to try collecting chaff in the RC, Stick to Wet Processed Beans!


2) Your blower rpm's/voltages seem low. Is the blower in a heat spiral? Have you cross-drilled the manifold?

3) Oh yes air expands when heated.
Edited by oldgearhead on 02/02/2014 8:41 AM
No oil on my beans...
 
keving
OGH Thanks for the input.
1 - I though about this chaff issue when I started considering using an oriface plate if hole size is small - will it plug? Right now I just increase blower and remove board a few seconds. This flushes all chaff form the roast chamber. I am going to look into this more as I progress with the roaster. I just want to get a couple of good profiles down befoe experimentation - getting a good profile is my experamentation right now! :)

2 & 3. I dont think I have a heat spiral. This is based on the observation that even before heat is applied the settings are very low to loft the beans. I do have to turn it down slightly from there once heat is applied to maintain the same flow regime. This is with a 1.5HP encased spa blower motor and I think this size of motor is way overkill for 1/2# batches. Eventually I will increase to 1.0 to 1.5# batches and tie in the other heat element - which is disabled right now.

Also, I did not cross drill any ports below the element. Once I get some video shot I hope you and the other seasoned veterans on here will critique the flow - to my unskilled eye it looks pretty good.

Report - tried the huehuetenego this morning - tastes very good. To me tastes like it is missing a little of the choc taste at the end that I have experienced in the past. I think I need to extend a minute or so more after 1st crack with a little more heat reduction. Total roast time on this batch was 12:30. Next target will be 13:00 to 13:30. My old popper used to go to about 14:00 with this bean. Also passed some on to a friend who was used to the coffee I brewed with the old popper - he said don't change a thing - said it is his and his wife's new favorite. So........you know, now I have to modify the profile just a little bit more - cant help it!!!!!!
 
oldgearhead
Cross-drilling the manifold has nothing to do with bean movement. It raises the blower motor RPM for better cooling of the motor. The easiest way to test motor heating is to run the blower without the heater at say, 20% for 10 minutes and record the RC temperature rise..
No oil on my beans...
 
keving
I am seeing 20 degrees F increase at what I estimate to be 20 percent power to blower. It leveled out by the end of the 10 minute period. Would this be considered an acceptable range or do I need to be looking at holes to keep things cooler.
 
oldgearhead
That is only slightly less than what I observed. Why not drill the holes and re-test. If you don't like the result, a couple of pieces of tape will seal them up again.
No oil on my beans...
 
allenb

Quote

keving wrote:

I am seeing 20 degrees F increase at what I estimate to be 20 percent power to blower. It leveled out by the end of the 10 minute period. Would this be considered an acceptable range or do I need to be looking at holes to keep things cooler.


While it's nice to get the most bang for the buck in equipment longevity, I really don't think it's worth the effort of drilling holes and running a vacuum motor at high speeds with the extra noise to "possibly" gain an additional year or so in motor life span.

I ran a vacuum blower more than twice/week for at least 6 years at no more than 15 to 20% load and no winding or bearings issues. Of course, if you're ever planning on going into production in a commercial setting then it makes sense to reduce equipment maintenance costs any way you can.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
oldgearhead
Drilled manifold - The reasons why I incorporated it:
1) At the time I was using a router speed controller that I could not turn down enough.
2) My design was/is based on blower inlet air temperatures in the 130-150?F range and I did not want to 'stack' motor heating on top of that.
3) The drilled manifold placed the R.P.M. range required for a on-pound roast right where I wanted it,
70-100 Volts for cooling and 60- 40 volts for roasting.

I credit member 'Imclaren' for this great idea..
No oil on my beans...
 
keving
Thanks for the input on the blower - all valid points.

Today I have another question -

Thermocoupler placement and type.

I have read through several posts and have seen various placements for thermocouplers and everything from bare wire to the type I have which is basically a 1/4" npt threaded encased sleeve about 1" long with a big headed probe sticking of the end - it may not even be connected to the case as seen in one of freshbeans or seedlings posts. I mounted it pretty much where everyone says not to - in the stainless base of the roast chamber. I did insure it is out of the main stream of the blower, but I think it is acting like a big heat sink as it is reading about 100F lower than it should based on 1st crack temp readings.

I have seen folks run it into the beans from above - which I can do, but does anyone truly have an accurate bean temp with this type of roaster? I see beautiful profiles recorded on many threads using the Artesian and I am amazed at what looks like bean temp accuracy. Is there a true sweetspot?

I am just curious and have done a LOT of reading through the threads and have found a lot of discussion regarding this issue. Right now I am just using a reference temp off the PID when I hear 1st crack and going more by sight, sound and ROR although ROR is not truly accurate when I am off over 100F (lower than actual temp.) Guess I just insure a positive rise in temp throughout the process slowing rate between 1st crack and finish - roughly using OGH's manual PID % numbers from his post.

I have a flat plate tipped TC that i was thinking of trying for the environmental temperature and see how it does for that reading.


Planning on shooting some video this weekend.
 
tamarian
I'm using position 6 indicated here: forum.homeroasters.org/forum/attachments/tcloc.jpg

I think it matters that the probe sticks inside at least 2 inches, but not long enoough to cross the path of hot air and violent movement. It seems accurate enough to get 1st and 2nd crack dead on (200C, and 229C). The only area where it seems slight off is at drying. Turning yellow is usually at 150C, but on this setup I get yellow around 155-160C.
Wa'il. 1 Kg PID'ed gas-fired fluid bed roaster, GS/3MPS, K10F
 
keving
Tamarian, thanks for the info. Your TC placement looks like it is for the Sivitz style chamber which blows air up one side of the chamber if I understand it properly. Not sure it will work for my cylindrical chamber. The round chamber I am using blows air up the middle and sprouts it outwards towards the glass sides of the chamber. Trying to get the probe out 2" would place it directly into the air stream as there is less than an inch between the sides of the chamber and the stream. This is where the challenge occurs. Right now I am at about .75" out from the side and roughly 1" under the bean surface. Just seems to be acting as a big heat sink.

Did 3 pounds today (6 1/2# batches - will upload video tomorrow) and temp is consistently reading right at 315F when 1st crack starts. Guess I can use this point for reference. Haven't taken any roasts to 2nd crack so I'm still guessing what temp my PID would read at that point in the roast. It's OK though as I usually pull the roast right before 2nd crack anyways.
 
tamarian
If your thermocouple is bendable, you can place it lower and bend it upward. If your thermocouple is thick, try a thinner one, where one inch can work.

If first crack happens at 315F, at what temperature does the beans turn yellow? If the spread is normal, around 90F between yellow and 1c, then you're o.k., you just need to keep in mind the difference. But if the spread is smaller, then it is no longer linear, and it would be hard to fine tune roast level. You can still go by sight, sound and smell, but might be worth resolving the issue to help with logging for repeatability.
Wa'il. 1 Kg PID'ed gas-fired fluid bed roaster, GS/3MPS, K10F
 
oldgearhead
Keving,
I ran my roaster for several months with a very long
thermocouple from the top plate into the bean mass,. and the temperatures were right on what the reference books say: 400-410?F first crack and 420-430?F finish. However, I also tracked everything with a second thermocouple located 1.5 inches below the perf plate. What I found was that after T+3 minutes the tc located below the perf plate tracked the BMT probe with an offset of -30?F. Therefore, two years ago, I stopped using the BMT probe and never looked back. I sold the long tc to ginny.

It's hard the tell from this image but the long tc is positioned one inch from the inside wall of the bake-a-Round, and two+ inches into the beans.
oldgearhead attached the following image:
dsc_0206.jpg

No oil on my beans...
 
keving
FIRE IN THE HOLE!!!!!!

To date I have done about 20 roasts on this new roaster and I'm starting to fine tune some of the roasts and getting really good results. Except for roast #17 - that one was sort of overdone!!

Due to operator error the beans to stopped moving for what I will estimate to be about 20 seconds. Without getting into too much detail, lets just say you should NEVER EVER run a large shop vac at the same time, on the same circuit, as your electric roaster. Further, you should NEVER leave the roaster unattended - even only 10' away. Otherwise, you may end up with results similar to mine.

The thing that will complicate the matter is once beans catch fire, and once the shop vac is turned off, the blower will go back to normal speed and start blowing nearly weightless flaming bean embers along with fire out of the top of the roast chamber. This will Happen. I promise.

I never imagined 275 grams of coffee beans could make so much smoke!! I was unable to take any pictures during the actual fire event as I was rather preoccupied with other things at the time. But below is a picture of the aftermath my neighbor took when things were back under some resemblance of control. My neighbor was there because he was checking to see if my house was on fire (this is the guy who I helped to build the case of the roaster).

Fortunately, I made sure I was clear of the carport overhang before I began roasting. But I'm telling you, the amount of smoke was mind boggling. And the heat those beans put out was just as amazing.

Never was there a real danger of damage to anything other than the roaster, but if I wouldn't have made sure before starting to roast that I was clear of any structures it could have honestly turned out differently.

I ended up placing the roaster on it's side and blowing the char out the top to keep it from messing up the roaster case any worse than it already was.

It took about 1.5 hours to clean everything up but the roaster is fine and I did 3 roasts after the event which had no taste of soot.

So there it is - what NOT to do when roasting. I learned a lot from this experience and hopefully anyone reading this will learn from my errors.
keving attached the following image:
fire.jpeg

Edited by keving on 02/25/2014 7:58 PM
 
JETROASTER
I believe you have found "Third Crack". Congratulations on the good roasts. ....and good luck with all the new safety changes.
Cheers, -Scott
 
shsesc
I'm not quite sure what kind of vacuum motor to get, and what kind of housing I need to use it. Can anyone provide some insight? Close up photos are great, I need to know specs though. I have a sew & vac store in my town, and I know the new owner is a nice guy, he'd probably find me something if I knew how to explain what I need.
 
shsesc
I went back and read more closely, 1.5HP and use pvc to isolate the blower from the heat source. Any other specs I should be aware of?
 
allenb

Quote

shsesc wrote:

I'm not quite sure what kind of vacuum motor to get, and what kind of housing I need to use it. Can anyone provide some insight? Close up photos are great, I need to know specs though. I have a sew & vac store in my town, and I know the new owner is a nice guy, he'd probably find me something if I knew how to explain what I need.


For your questions and any others to help you with your build, start a new thread instead of piggy backing in Kevin's build. This also keeps your build in a separate place where everyone can follow it and contribute. ThumbsUp

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
shsesc

Quote

allenb wrote:



For your questions and any others to help you with your build, start a new thread instead of piggy backing in Kevin's build. This also keeps your build in a separate place where everyone can follow it and contribute. ThumbsUp

Allen


That makes perfect sense, I will try to organize my questions into new thread soon. I didn't mean to hijack the thread, I was just excited to get started. I apologize.
 
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