Homeroasters - Home Roasting Coffee Community » BUILDING A ROASTER » Drum Roasters
Who is here? 1 guest(s)
Page 5 of 5: 12345
 Print Thread
Double Barrel Blending Roaster
Lylabrown
Top  #101 Print Post
Posted on 07/08/2013 12:36 PM

Quote

Thanks Russ. I see you have plots showing BT and ET how do you get BT and do you think the shaft collars would hold well enough to use that approach to get the BT?

Hey rustic_roaster,
I doubt the shaft collars alone could handle the sideways load placed on them by the beans. The photo you referenced was from an early setup where I was only measuring the ET (and controlling via PID). Once I got the TC4C I had to devise a way to get the BT as well. Here's what I came up with...

imageshack.us/a/img824/9747/fj1n.jpg
I took a chunk of aluminum and drilled two 1/4' holes on the backside near the top & bottom edges, then "dremeled" an 1/8" slot between them. On the lower hole I added a set screw to "lock" the aluminum tube into place. The thermocouple wire runs through the front plate of the roaster - into the upper hole of the block - along the slot - and into the tube seen here:

imageshack.us/a/img835/3057/rkor.jpg
The thermocouple tip sticks 1/8" out of the end of the tube. I wrapped the wire just before the tip with teflon tape, then pushed it back into the tube-end for a snug fit.

Here you can see the ET probe which runs up from the control box inside a stainless tube:
imageshack.us/a/img28/5374/f2vx.jpg

After 3 dozen or so roasts, everything has held steady with no need for adjustments, tweaks, etc.

Russ
 
Erik
Top  #102 Print Post
Posted on 08/09/2013 5:18 PM
Fantastic build. Very inspirational.ThumbsUp
 
Dan
Top  #103 Print Post
Posted on 08/09/2013 5:56 PM
Wonderful progress and a great build. Thanks so much for sharing it with us.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Web
allenb
Top  #104 Print Post
Posted on 08/09/2013 8:00 PM
Plus 1 on the positive comments!

The quality of build and high level of functionality makes this something I would think should eventually end up in cupping labs around the country. When you see the costs of Probat and other "professional grade" sample roasters being through the roof I'd bet you could enter the market if you found a way to efficiently fabricate this roaster.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Lylabrown
Top  #105 Print Post
Posted on 08/10/2013 2:17 PM
Wow. Thanks for your compliments & praise. I'm glad I can return the favor and provide inspiration to others.

The thought crossed my mind to do a trial run of fabricating a few of these & selling on ebay. But the liability issues are a major concern. Besides, I borrowed heavily from Dan's sample roaster design, I'll leave it to him to take it to market.

Russ
 
Lylabrown
Top  #106 Print Post
Posted on 08/10/2013 2:51 PM
With all the talk lately about MET, BMT, Exothermia, Etc. I thought I'd run a little experiment by placing a thermocouple inside a bean to get a true BT reading to compare with the BMT.

I took a type K thermocouple with a tiny 1/16" bead and hooked it up to a pid controller for temperature readout and calibrated it to match the BMT probe on the roaster @350f. I then drilled a 1/16" hole halfway through a green bean and inserted the thermocouple tip, it was a nice tight fit.

imageshack.us/a/img543/8408/r9hj.jpg
(photo taken post-roast)

The in-bean-probe was placed in the bean mass seconds after charging the drums with beans. The thin wire on the probe allowed it tumble with the rest of the beans in the drum. Here's a short video showing the setup & action:



I manually logged the in-bean-probe taking readings at 30 second intervals then plotted them on the roastlogger chart after the roast. Here's the chart:

imageshack.us/a/img197/5047/v0ut.jpg
(click for larger image)

The results aren't too surprising, but do offer some insight into whats happening within the bean. I find the steady temperature rise within the bean after FC (while the other probes are flat/declining at 50% power) interesting.

Russ
 
Dan
Top  #107 Print Post
Posted on 08/10/2013 3:48 PM
Russ, That TC method is used by scientists wanting to know the same thing. I've done it in my sample roaster, too, but its been a while.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Web
allenb
Top  #108 Print Post
Posted on 08/10/2013 3:48 PM
Russ,

Thanks big time for coming up with and doing this experiment! While we've all heard of labs determining that the internal bean temp is around 380 F during first crack it's really nice to see confirmation by one of our own members.

What I find very interesting is this. I assumed that while the bean is in it's so-called exothermic reaction stage during first crack that the core of it would be generating a higher temperature than the outside while the rest of the bean is shedding its steam from the reaction, but instead, the beans internal temp flat lined (mostly) for the first 30 seconds or so of first crack. This is the opposite of what I would have imagined to be the case.

The mystery continues (at least for me).

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #109 Print Post
Posted on 08/10/2013 3:51 PM
OTOH, I've also heard that the core of the bean is where the bound moisture is being produced chemically. More confused than before.
Shock

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Dan
Top  #110 Print Post
Posted on 08/10/2013 3:58 PM

Quote

the beans internal temp flat lined (mostly) for the first 30 seconds or so of first crack. This is the opposite of what I would have imagined to be the case.


And, the ET had been dropping for almost two minutes at this point. With two variables at work, we don't have a clear picture of what's really going on. It is for this reason that scientists use a completely flat profile for their roasts in order to control for that variable.

Plus, we don't know if the two TCs and the circuitry they are attached to have been calibrated. It would be fun to redo this with these concerns in mind.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Web
allenb
Top  #111 Print Post
Posted on 08/10/2013 4:05 PM
Good point Dan but, the internal bean temp starts climbing just past minute 10 while at the same time environment temp is still dropping. This matches my bean temp sag sequence which is around 30 seconds. A new abbreviation is in order "BTSS" as we don't have enough of them yet!

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Dan
Top  #112 Print Post
Posted on 08/10/2013 4:10 PM

Quote

the internal bean temp starts climbing just past minute 10 while at the same time environment temp is still dropping.


That could be evidence of an exothermic reaction.

And I'm thinking about yet another abbreviation: BBS (Bean BS), for all those unexplained temperatures and roasting anomalies. ;)
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Web
allenb
Top  #113 Print Post
Posted on 08/10/2013 4:37 PM
I think you've hit the nail here. During the initial seconds of the exothermic reaction we're producing steam from the bound moisture release but after so many seconds of this release the reaction is still taking place and temperature climbs at a faster rate than it would at the lower environment temperature.

I'm probably wrong with this but what the heck!

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #114 Print Post
Posted on 08/10/2013 4:40 PM

Quote

Dan wrote:

And I'm thinking about yet another abbreviation: BBS (Bean BS), for all those unexplained temperatures and roasting anomalies. ;)


Does the second B stand for anything related to the Bovine family of animals?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Dan
Top  #115 Print Post
Posted on 08/10/2013 4:58 PM
LOL!
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Web
Lylabrown
Top  #116 Print Post
Posted on 08/10/2013 7:12 PM
Allen & Dan,
Thanks for the interesting & humorous analsys. I'll do another test tomorrow with a linear profile and a tighter set of data points (15 second intervals) to try and clarify what's going on around 1st crack. I'll also paste the thermocouple wire where it enters the bean (not the tip) with high temp rtv. Which will hopefully prevent anomalous readings from steam escaping out the drilled hole and better mimic an intact bean.

Also, the BT probe & IBP (In Bean Probe Grin) are calibrated and stay within 2 degrees of each other at static & ramping temperatures.

Russ
 
Dan
Top  #117 Print Post
Posted on 08/10/2013 9:43 PM
Russ, Sounds like a plan!!!
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Web
Lylabrown
Top  #118 Print Post
Posted on 08/11/2013 2:51 PM
So I ran another test with a 350f pre-heat then 80% power throughout the roast. I let it run well into second crack this time. The temp readings were at 15 second intervals.

For reference, here's the log showing the new & old tests without the in-bean readings.
img689.imageshack.us/img689/4754/fnii.png

For the new test I loaded one drum with beans (the one with with the BT probe), and covered the opening of the other with sheet metal. As a result, the profile ended up being fairly similar.

For better resolution & smoother curves, i manually entered the interval plots into the roastlogger "log" in place of the E temp plots, then loaded it on top of the actual log. Here's the resulting chart:

img24.imageshack.us/img24/5629/x890.png

The "hump" during first crack is still visible, but less dramatic this time.

I'd love to see a chart with 1/10 second+degree readings inside the bean at & around first crack. Even better would be reading while the bean is rapidly expanding (cracking).

Russ
 
Dan
Top  #119 Print Post
Posted on 08/11/2013 3:56 PM
Russ, This is very interesting and not as dramatic as I'd hope we'd see! Then again, this was measuring temperature and those science guys measure energy. The difference is like measuring voltage versus wattage. Thanks so much for doing this and posting it, too.

Dan
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
 
Web
Page 5 of 5: 12345
Jump to Forum: