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Enhancing My HotTop (5.1 of 5) ? Extreme Mods
RAG

Quote

ciel-007 wrote:

..... Hottop sells for about $10.
ciel


You gotta love hottop for that reason alone. Ok so I haven't drilled the hole yet but I put in a dpdt switch for switching from the built in thermocouple to one i made with left over wire located in the eletronics area. Two fold benefit. it works as a heater on switch and also allows monitoring of electronics.
 
RAG
If attempting back to back roasting, is there a way to get the chaf from above the tray, that sits in the well that falls out when you take off the front glass? I built a metal tube vacuum adapter that cleans the inside pretty well but this area seems stubborn.

Thanks
 
ciel-007
Venting the Plenum Cover

After hundreds of roasts in the RAF-1 Extreme, I can report that the modified roaster performs very well. Although this roaster's appearance may seem novel, let me assure you that it continues to perform with the precision and reliability that has made the Hottop name legendary. However, I continue do seek ways to further enhance this singular design. Here is one tweak that I am experimenting with. It involves a small modification to the Plenum Cover.

During roasting, the RAF-1 design encourages the rise of hot gases from the chamber into the extraction pipe above; concurrently, fresh air is naturally drawn into the chamber through the rear of the roaster. This spontaneous convection plays a useful role when the BMT exceeds 300F; that's the moment when the moisture inside the beans begins to escape, and the critical drying process begins. Those of you roasting with an RAF-1 modification will have noticed that this moisture finds it way into the Plenum, and may even spill out the back of the Plenum through the exhaust fan (even when the fan is OFF). Those hot gases may also coat the fan blades with residue (I do not use any filters in order to maximize fan efficiency). Typically, I leave the cooling fan OFF during this drying phase until the verge of first crack, when I turn the fan ON (level 1) to expel smoke and gain better control over ROR.

I have been experimenting with a small modification to the Plenum Cover that reduces moisture accumulation and residue build-up. Take a look at the attached photos. The photos show:
(1) that the knob atop the plenum cover actually conceals a vent opening
(2) an ordinary sink stopper has been attached to the knob, and may be used to open and close the vent opening at will.
(3) removing the knob to open the vent allows rather large amounts of moisture to naturally escape without any need to activate the main cooling fan.

The vent works very well during the critical bean drying phase of the roast. Should you elect to try this tweak, don't forget to return the stopper to the vent opening before turning on the fan.

Ciel
ciel-007 attached the following images:
plenum_cover_1.jpg plenum_cover_2.jpg plenum_cover_3.jpg plenum_cover_4.jpg plenum_cover_5.jpg

Edited by ciel-007 on 05/12/2014 1:09 PM
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
snwcmpr

Quote

when the BMT exceeds 300F; that's the moment when the moisture inside the beans begins to escape

Hmmm, I always thought that at 300F BT the moisture had already escaped and drying was complete, theoretically.

Ken in NC
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
ciel-007

Quote

snwcmpr wrote:

... I always thought that at 300F BT the moisture had already escaped and drying was complete...


Interesting...
Care to share where the theory came from?
Ciel
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
ciel-007
Bean Drying Phase in the RAF-1


Quote

snwcmpr wrote:

... I always thought that at 300F BT the moisture had already escaped and drying was complete, theoretically...


Ken, I was curious about the theoretical claim you advanced. That motivated me to do more reading about bean moisture content, and to conduct a few experimental "Bean Drying" trials with the RAF-1.

So far, the articles I consulted suggest that the moisture content of green coffee is generally thought to be approximately 12%. Further, according to my understanding of Willem Boot's writings, the objective of the drying phase is to reduce that bean moisture content down to approximately 2%. In other words, during the critical drying phase, over three quarters of the moisture inside the bean must be "vaporized" away.

Bean Drying Trials: Given the magnitude of moisture being vaporized within such little time, it should be possible to see evidence of this phenomenon as it happens. Under that assumption, I conducted several trials in the RAF-1 to document the BMT at which a perceptible amount of vapor would begin to rise from the roasting greens. I hypothesized that if Ken's "theory" was correct, then there should be visible signs of vapor escaping from the roaster before a BMT of 300F was reached.

Some may fault me because the trials did not involve sophisticated measuring instruments. I employed simple visual cues; namely, I looked for the moment at which my eyes could detect a noticeable amount of vapor rising from the vent hole in the Plenum Top of my modified Hottop (RAF-1) via natural convection (fan turned OFF at all times).

Findings: My observations found that little or no vapor was noticeable prior to BMT 290F. When vapors began to escape from the Plenum Top at BMT 290F, they were not sufficiently plentiful to be easily photographed. Photo 1 shows a more noticeable amount of vapor escaping at BMT 300F. The visible amount of vapor continued to increase as the BMT continued to rise. Photo 2 shows a even more dramatic amount of steam escaping at BMT 320F.

Interpretation and conclusions: As BMT approaches 290F, the temperature of the moisture (and pressure) inside the beans is increasing; however, little humidity appears to be leaving the bean (possibly because of the hard outer shell of green beans), and little bean drying seems to be occurring at this time. However, once the BMT exceeds 290F, the rising gas pressure inside the beans would be such that vapor flares though the pores of softening cell walls, thus marking the beginning of the critical bean drying phase.

The observations from several bean drying trials lead me to conclude that:
(1) The RAF-1 mod makes it easy to spot the moment at which the critical bean drying phase begins
(2) The design of the RAF-1 allows moisture to easily escape from the roasting chamber through simple natural convection (no need to cycle Hottop fan ON & OFF for drying)
(3) Very little water vapor actually escapes from the beans prior to BMT 300F
(4) When BMT 300F is reached, the critical bean drying phase (during which 75% of the water must be expelled from the beans) has just barely begun
(5) The popular theory that the bean drying phase is complete by the time BMT reaches 300F would appear to be unfounded.

Ciel
ciel-007 attached the following images:
photo_1_bmt_300f.jpg photo_2_bmt_320f.jpg

Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
ciel-007

Quote

turtle wrote:

I am thinking of implementing your mid draft draw fan mod but I want to make the rear box out of sheet metal instead of wood. Not good at prototyping so dead in the water there.

Do you have any measured drawings of your wooden box mod so that a "tin man" could use them to bend and fabricate a sheet metal box out of AC duct metal?


Mick, Plenum dimensions of are not critical. The one in my photos measures 4"x7"x9". I used wood because it made it much easier for me to build various experimental boxes (RAF-Alpha, RAF-Beta, and finally RAF-1).

If you prefer metal, you might also consider taking a look at RAG's alternative - the box from a First-Aid-Kit.

http://homeroaste...post_46845
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
ciel-007

Quote

smico wrote:

... last weekend I have finally built an ad-hoc RAF...
... first roast was successful...
... I have some other mods that will be documented soon...



Congrats Miroslav!
I very much look forward to admiring you handiwork, and learning from your astute innovations.

Ciel
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
ciel-007
Bean Drying Phase - A Follow-up

Quote

ciel-007 wrote:

Interpretation and conclusions:
As BMT approaches 290F, the temperature of the moisture inside the beans is increasing... once the BMT exceeds 290F, the rising gas pressure inside the beans would be such that vapor flares though the pores of softening cell walls....

The observations from several bean drying trials lead me to conclude that:
...
(3) Very little water vapor actually escapes from the beans prior to BMT 300F
(4) When BMT 300F is reached, the critical bean drying phase (during which 75% of the water must be expelled from the beans) has just barely begun
(5) The popular theory that the bean drying phase is complete by the time BMT reaches 300F would appear to be unfounded.


Quote

oldgearhead wrote:

... the main problem, I have with the 'Bean Drying Phase in the RAF-1' is "perceptible amount of vapor"... was the vapor trapped and weighed? ...


Following OGH's feedback, I elected to repeat the earlier bean drying trials using a more objective method.

Follow-Up Bean Drying Trials:
For the new bean drying trials, I used a digital scale to quantify the amount of moisture being lost during roasting. The trials involved roasting 300g of Columbian greens that were at an initial room temperature of 75F. The beans were roasted in accordance with the profile described at the following link:

http://homeroaste...post_46459

After loading them into the roaster, the beans were allowed to reach a BMT of 300F; at that point, the beans were ejected, weighted, and then immediately returned to the hot chamber. At this point the beans were observed to weigh 292g on the digital scale. The method used to eject the beans, while maintaining the Hottop at full heat and roasting power is described in the following posts:

http://homeroaste...post_40019

http://homeroaste...post_40020

Following their return to the roasting chamber, the beans were allowed to complete the cycle as described in the profile. At the end of the roast, the ejected beans were immediately placed on the digital scale and weighed again; the final weight was observed to be 258G. In order to ensure that this final weight was confined to measuring only moisture loss, the beans were weighed along with all the chaff that I was able to recover from the roaster.

Follow-Up Findings:
During the entire roasting cycle, the mass of the Columbian greens lost a total of 42g. The ratio of 42g/300g is equivalent to a 14% weight loss. That percentage is comparable to the moisture content frequently reported in green beans. More importantly, by the time the greens had reached a BMT of 300F, only 8g of the mass had been lost; the ratio of 8g/300g is equivalent to a 2.7% weight loss. The question that the trials were intended to address is this: How much of the entire bean drying process has actually occurred by the time the BMT reaches 300F? The answer is provided by the ratio 8g/42g, which is equivalent to 19%. In other words, by the time that BMT achieves 300F, less than 20% of the moisture has been removed from the roasting beans. These new empirical results actually concur with the earlier, albeit less objective trials, based on the vapor that was perceived to be escaping from the Plenum of the RAF-1 during roasting.

FOLLOW-UP CONCLUSIONS:
...
(3) Less than 20% of the moisture actually escapes from the beans prior to BMT 300F
(4) When BMT 300F is reached, the critical bean drying phase (during which the remaining 80% of the moisture has yet to be expelled) is still at an early stage
(5) The belief (still held by some roasters) that the bean drying phase is complete by the time BMT reaches 300F would appear to be misguided.



Ciel
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
Barrie
Good job, Fern! The chaff as a proportion of the total is still an unknown, and it would come off after the 300 mark, of course. Intuitively, it seems unlikely it would account for a large fraction of the total? Each of us who reads this report will have a different reaction. My career in the sciences induces respect for the methodology, given the limitations of your "laboratory." The homeroaster in me, with some established routines that do not include any change in settings once the drying/yellowing phase is over, encourages further approval. Grin
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
Barrie
Just finished roasting two 232g batches of Happy Mug Peru Sol y Cafe. These beans are not big chaff producers (don't know the processing), but there was a fair amount in the chaff tray at the end of FC+ roasts. My scale measures to the nearest gram and the weight was ZERO!

Incidentally, the beans are the prettiest I have seen. Good very uniform size, and textbook-perfect color changes during the roast. A really enjoyable experience.
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
smico
While waiting to find some time to build custom box, I picked up an old toolbox that I had laying around and spent a weekend building my ugly temporary RAF setup.

1. Pipe connection to the top filter
I used Dremel to cut round hole in mesh of the top filter to fit end of the pipe in.
Then I rolled two layers of aluminum foil around the filter mesh.
High temperature silicone secures the end of pipe, and it makes the connection air tight.

2. Box
Box is made air tight with layer of high temperature silicone on one edge.

I could not find a cap so I used a hockey pack to close the top vent.

I did just 4 roasts so far, and I have full control of the roasts, similar to the control of the original HT. I have to spend more time on temperature measurements of internal components during back to back roasts.

So far so good.

Ciel, thank you again for this gift.

I will report further on usage details as I use the new setup more.
smico attached the following images:
raf_open_box.jpg raf_back.jpg raf_front.jpg raf_side.jpg connect_pipe_to_top_filter_top.jpg connect_pipe_to_top_filter_side.jpg

Edited by smico on 06/29/2014 11:47 AM
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
frachlitz
Simco, thats looks promising!

What kind of pipe did you use?
 
smico
As per Ciel's instructions, I bough 1.25" chrome plated drain pipe kit for $20 in Home Hardware. Pipe is 12" long, and I did not have to cut it at all.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
Barrie
i see from the HB forum that Fern (Ciel-007) is moving on to a larger-capacity semi-pro roaster. He has made tremendous contributions to our information database as he has explored the possibilities with his HT, and I do hope we will continue to see his writings from time-to-time.
Thank you so much for everything you have done for our hobby, Fern. I wonder if your new community of roasters know how fortunate they are? ThumbsUp
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
ciel-007

Quote

smico wrote:

... While waiting to find some time to build custom box, I picked up an old toolbox that I had laying around and spent a weekend building my ... temporary RAF setup...



Miroslav, I admire your creativity. Congratulations on a cool RAF mod!

I look forward to hearing more about how the mod may have influenced your roasting experiences, and profiles.

Ciel
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
okmed
First of all let me say that I'm a newbie to this site, and to roasting. Second let me say thanks to all the people that contribute here and the people that run this site. It was this site that helped me make my decision to purchase the Hottop. Special thanks to ciel-007 who's' work on "Enhancing My HotTop" mods impressed me so much I had to do them all. By the way Fern, I have the newer type K thermocouple and shorting it out works perfectly for the "Cracking the 165F Barrier" mod.
The following attachments show my mods and the slight differences to accommodate my limited head room under my kitchen exhaust/microwave. I only had 15-1/2" under the exhaust/microwave so I made it 8-1/2" x 8-1/2" x 4". It should have been a little wider but I offset it towards the back to move the pipe over and create just enough room so that the charging funnel still fits. As you can see I used copper pipe and fittings to get more offset. Also due to the limited head room, I made the rear cover removable instead of the top . You can see the large flat top screws and cam plugs I found at Home Depot to facilitate that.
I also made a simple cardboard chimney which works very well to direct the exhaust.
I have two thermocouples and a TC4C kit (with RoastLogger software) on order and am looking forward to completing that final mod so I can better track and record my roast profiles.
Thanks again to all who contribute here.
okmed attached the following images:
img_0190.jpg img_0189.jpg img_0187.jpg img_0186.jpg img_0183.jpg img_0182.jpg img_0181.jpg img_0180.jpg

Edited by okmed on 09/07/2014 6:13 PM
RAF-1 Extreme (modified B-2K) Hottop with HTC+TC4C, HG-One grinder, Bezzera Strega.
 
allenb
Hi okmed, you've done some fantastic modding here. I especially love the copper plumbing work! Reminds me of vintage locomotive steampunk in some of your photos.

How's your roasts turning out?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
okmed
Thanks Allen, as far as my roasts go I'm still on the learning curve. Have only done 8 roasts so far ( last one with the mods ) and none have been bad. Even the wife thinks they're pretty good.
Just received my thermocouples and cables for the HTC/TC4C interface so I will be busy with the install but look forward to developing a RoastLogger data base to help with my learning curve.

Milan
RAF-1 Extreme (modified B-2K) Hottop with HTC+TC4C, HG-One grinder, Bezzera Strega.
 
smico
Great job Milane. This is the nicest installation so far. I have to ask management to remove photos of my installation.
Regards,
Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007

Quote

okmed wrote:

... I offset it towards the back to move the pipe over and create just enough room so that the charging funnel still fits. As you can see I used copper pipe and fittings to get more offset...


Milan, congratulations for your improvements to the initial RAF-1 design.
I especially like your clever use of offset fittings on the Extraction Pipe, in order to further increase clearance for the bean charging funnel.
Keep up the great work!
Ciel
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
ciel-007
Here's a photo showing an alternate way of creating the RAF-1 mod.
More photos and details are available at the following link.

http://www.home-b...ml#p408655

Ciel
ciel-007 attached the following image:
alternate_raf-1_mod.jpg

Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
jinx
I have been tinkering with my hottop this weekend and while things are drying, I wanted to note a few breakthroughs.
First though- I'd like to pause and say thanks to those who came before me and pierced ahead, making the hottop better than it is in stock form.

So, here's the first simple mod- I tricked the chaff tray switch.
I didn't like the chaff tray switch, so I snipped a small piece of thin aluminum and bent it into a rough C shape. I slipped both ends into the slot where the switch sits and managed to keep the switch depressed all the time. I think I can figure out whether or not I have the chaff tray in, or if I cleaned it out. It was just bugging me.

Next mod- I created bean cylinder fins that are taller than the stock helix wire. I used pop rivets to attach them, and folded over some sheet metal for the shapes. The fin near the glass is hooked to keep those window clinging beans on the move. Results to come.

I really wanted to try the 165f barrier mod, but judging from what I read as an outsider, that mod is not really that reliable. JimG says a transistor would do the trick but there's no info beyond that. I generally use the cool down time to vac out the roaster anyway and, I use one vac to blow cool air in as another vacs out the chaff. It cuts the recovery time to just a few mins.

Next mod - Flipping the fan. Way too much chaff and residue in the motor area caused me to take a close look at the raf mod. But, building a box and pulling air from the vent with the current fan is a long way around. One question I have is - why use exhausted roast gases being pulled up through the sink pipe, as the input into the motor area?
I took apart the fan in the rear of the roaster, and cleaned it up as best I could. Then, I noticed that if you remove just the fan from the frame, you could simply flip it over and reverse the direction. This would now make the fan blow directly onto the motor and computer board, and then on into the roaster chamber.
As a means of helping to control ET in the chamber at end roast levels, I might employ a sliding vent at the top of the hottop, where the small mesh smoke screen is. Opening that area to exhaust, even for 10 seconds, allows alot of the heat to escape. Modulating it with a slider door should be quite acceptable. If need be, I could pull the chaff tray open to allow cooler air to enter.

The mod I am not doing tonight is the bean cooling tray. My thought is to raise the legs of the roaster by another inch. Then, remove the fan and screen in the cooling tray, and create a chute to land the hot beans in an external tray below. I always use an external bean cooler anyway, why not make it easier and faster. Maybe I can get away with diverting the beans to the front so I don't have to destroy the existing fan.

I am about to setup my indoor winter roasting station, as I have been doing outdoor roasting all summer. I did this last year, but didn't write up a thread on it. Its basically a hood design, but I use an inverted, large sterlite plastic container as my hood. I have it up on a few blocks of wood at the corners, and on the top, I use a powerful wood stove squirrel cage fan to extract all of the fumes out of the upsidedown box. Out of the squirrel fan, I attached dryer vent tube at 6", and it goes about 4 feet into a sheet of plywood, that acts as a block for the window. The window has nice trim work around it and a custom screen insert, I simply matched that for size and put duct tape on the seam. The window opens fully with a crank arm in the casement, so the plywood is there until spring. There is zero incoming cold air. There is also zero smoke leakage from the hood, the fan, or the duct work. Does it look silly, yes. But sometime silly does the job. I have checked repeatedly on the safety of this, hot spots do not occur anywhere. There's too much cool air incoming around the roaster for any heat buildup. Its all sucked up by the fan and duct. The fan has a dimmer on it, and its fairly silent. I suppose that if I were to create a vertical exhaust pipe from the roaster's top screen, upwards to the squirrel fan, I could pull some pressure from the hottop, and cool it down if needed.

More to come as I tinker late into the nights....
 
jinx
I woke up this morning with the realization that the chaff tray switch needs to be open for the computer brain to reset itself between roasts. So, it seems as though my little scrap of metal will have to be removed.

Maybe if I can make a pull wire that hooks onto the arm of the switch, like a choke mechanism on a carb. Then I can hook the switch to being closed for most of the time, and release it so the computer resets itself.
 
turtle

Quote

jinx wrote:

I woke up this morning with the realization that the chaff tray switch needs to be open for the computer brain to reset itself between roasts. So, it seems as though my little scrap of metal will have to be removed.

Maybe if I can make a pull wire that hooks onto the arm of the switch, like a choke mechanism on a carb. Then I can hook the switch to being closed for most of the time, and release it so the computer resets itself.


What about a momentary contact no/nc switch?

I put one in to "fool" the thermocouple into thinking the roaster is cold so it can restart without having to drop to the "safety" tempature.

You will still want to empty the chaff tray after every roast as it fills up, at least mine does.
Mick - "Drinking in life one cup at a time"
"I'd rather be roasting coffee"

Roaster 1: San Franciscan SF-1
Roaster 2: Hottop B-2K+
Roaster 3: 2 kilo Chinese drum
Grinders: Mazzer Major - Forte BG (x3)
Pour over: Hario - Bee House - Chemex - Kalita - Bodum
Drip: Bunn CWTF15-1 & CW15-TC (commercials)
Espresso: Pasquini Livia 90 auto
Vacuum: Cona - Bodum
Press: Frieling - Bodum Colombia
 
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