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Enhancing My HotTop (5.1 of 5) ? Extreme Mods
ciel-007
Now Roasting 3/4 lb Loads - 38% More than Manufacturer Suggests

Here is a revised back-to-back roasting profile for the RAF-1 Extreme. My modified Hottop is now roasting nearly 4 lbs of greens in about 90 minutes. To accomplish that, I run 5 non-stop, back-to-back, roasts. I do not drop the beans until the roasting chamber approaches a temperature of 399F. I am now using loads of 344-346 grams (that's 3/4 lbs of beans per roast). In other words, the RAF-1 Extreme is roasting 38% more beans than the load suggested by the manufacturer for an "out-of-the-box" (unmodified) unit.

Profile for First of Five Back-to-Back Roasts
The RAF-1 Extreme is turned ON with the following settings:
-Fan is OFF (Level 0)
-Power at Maximum (Level 10)
-Time at Maximum (25 minutes)
-Temperature at Maximum (428F)
-Green beans (345 grams) dropped when roasting chamber approaches 399F
-It takes about 12.5 minutes for beans to reach FC
-When BMT reaches 384F (FC begins), Fan is set to Level 1
-When BMT reaches 410F, the Fan is set to Maximum (Level 4), and Power is reduced (as needed) to stretch the roasting time to 4 minutes between FC and SC.
-For M?lange Roasting, the first (of several) partial bean ejection begins when BMT reaches 422F (see "Tryer Function and Partial Bean Dumps During Roasting" posted earlier)
-Bean agitation arm in cooling tray is manually turned ON (see "Manually Activating Bean Agitation in the Cooling Tray" posted earlier)
-Eject button is pushed when BMT reaches 434F to empty roasting chamber
-As soon as the roasting chamber is empty, the roaster is reset, and the next roast is launched (see "Cracking the ?165F Barrier? posted earlier).

The above profile produces excellent Espresso beans. 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

Quote

Randy G wrote:

... you have a wood box and the plastic fan receiving hot gasses and particulates that enter differently than the original design. In case of a chamber fire or flash-over event in the roast chamber, chaff in the wood box could be ignited...



Randy, thanks for raising a good question.

Before posting about this modification, I roasted over 50lbs of beans during several months. The enhanced Hottop was subjected to non-stop, high-temperature, back- to-back roasting for two hour periods at a time. During those intense trials, I did not see evidence of a fire hazard. As you know, the factory Hottop draws quite a bit of chaff into the rear of the housing; I suppose that might pose a potential fire risk as well.

In the case for the RAF-1 Extreme, since no chaff is drawn up the metal Extraction pipe or into the Plenum, the risk of fire appears to be minimal. I used wood (instead of metal) for the Plenum because I am not equipped for tinsmithing. However, to optimize safety, the wood Plenum could easily be rendered fire-resistant by lining it with metal foil. 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
 
RAG
I would think this design infinitely safer than the stock hot gasses and chaff pulled through electronics and plastic. The tar residue buildup along with the chaff left to accumulate and bake in the internals and electronics.


Picked up my 1-1/4" pipe and stainless yesterday. I think I'll build the plenum out of ABS. I was going to replace the fan but decided to just pull the original out of its enclosure and put it in the plenum addition. I'm not concerned with exhaust fumes but I have some charcoal filter and a stock $3 microwave metal mesh I probably will use anyways. I have a bunch of 3" computer case fans and I think I'll add one to the electronics area while I'm at it.
 
smico
Hi RAG,
Have you completed thermal insulation of the back wall.
It would be nice to see some photos.
Thanks in advance,
Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007

Quote

RAG wrote:

... I think I'll build the plenum out of ABS ...



There are several types of Acrylonitrile Butadiene Styrene materials on the market with varying thermal properties. Some ABS materials are not intended to be used in long term applications where temperatures exceed that of boiling water. Is there a way for you to find out what is the maximum operating temperature of the ABS material you are planning to use? 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
 
RAG

Quote

ciel-007 wrote:

... several types of Acrylonitrile Butadiene Styrene materials on the market with varying thermal properties. .....


I got a sample and tested with hot air gun and seemed ok but your comment made me look up the spec's. Melting point around 225 F flash point 752 F. So you've made me rethink the plenum. Back to the drawing board.(I do have left over thermal blanket I could line the plenum with but kinda cheeezy).

I have not finished the fire wall construction, and time is an issue right now. Need to reassemble the Hottop and do some roasting.

My dremel tool is my metal working tool so I'm limited on metal fab equipment and skill. Made a great top cover for duct out of stainless but didn't take time to make a template and tried to put the duct hole in after with a knockout. Mistake.

Needed to review your article about mod's especially the
165 override . Think I'll switch to a thermocouple in the motor compartment instead of just momentary open.
 
ciel-007
Fire-Resistant Plenum

Quote

ciel-007 wrote:

Quote

Randy G wrote:

... you have a wood box and the plastic fan receiving hot gasses and particulates that enter differently than the original design. In case of a chamber fire or flash-over event in the roast chamber, chaff in the wood box could be ignited...



... the enhanced Hottop was subjected to non-stop, high-temperature, back- to-back roasting for two hour periods at a time. During those intense trials, I did not see evidence of a fire hazard... In the case of the RAF-1 Extreme, since no chaff is drawn up the metal Extraction pipe or into the Plenum, the risk of fire appears to be minimal...

However, to optimize safety, the wood Plenum could easily be rendered fire-resistant by lining it with metal foil. Ciel


Is there an alternative to lining the Plenum with metal to improve its fire-resistance? Yes, I believe there is. One could treat the wood with a fire retardant solution.

That can be done easily at home. Simply dilute 2.5 tablespoons of sodium borate (Borax) in 1 cup water; then apply it liberally to the wood. The goal is to saturate the wood with the solution, and then allow it to dry. This method can be used to make other natural fibers fire-retardant as well. Should chaff ever ignite within a treated Plenum, the inner wood surfaces would begin to smoke, then char; the sodium borate would undergo a critical transformation by the time the chaff would have self-extinguished. More specifically, when subjected to intense heat, the borax is transformed into a "glass-like" substance, which insulates the wood, and allows the natural fibers to char rather than ignite. This "glass-like" substance, in combination with the char, insulates the wood to the point where the wood effectively resists combustion.

In the unlikely event that a bit of chaff might find its way into the Plenum and ignite, the chaff would be consumed, and the fire extinguished, well before the structural integrity of the Plenum would be compromised.

The following link shows how to make, apply and test a Borax fire-retardant solution:

http://www.instru...retardant/
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

Randy G wrote:

... the rear wall of the roast chamber is now being cooled by cold air entering from the rear. This could affect the function of the thermal fuse in case of a chamber fire as well as possibly affecting the accuracy of the factory temperature sensor (more of a factor for models with the old-style button sensor).


Randy, thanks for raising yet another great question.

After you raised the question, I started paying special attention to the temperature readings displayed on my Hottop's Control Panel. After observing numerous non-stop, back-to-back roasts, I am finding that the readings don't appear to be any different from the temperatures displayed prior to the Reversed Air Flow modification. I searched for reasons that might explain why my "old-style button" sensor (mounted on the "rear wall") would not be affected as you hypothesized above. The explanation I am advancing below is tied to the fundamental design of the roaster.

A close examination of the Hottop's basic design reveals 24 vent openings on the side of the roaster (see box A in photo). With the RAF mod, when the fan is turned ON, a certain amount of cool air does indeed enter the roaster from the new back vent near the Plenum (see B in photo). However, the air flow from the relatively modest back vent is necessarily smaller in comparison to the larger volume of cool air entering through the 24 side vents.

Since the volume of cool air entering the back of the roaster is too low to have a measurable impact on the temperature sensor mounted on the back plate of the roasting chamber, that would imply that the safety of the roaster is not compromised by the RAF modification.

ciel
ciel-007 attached the following image:
24_side_vents.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
Improved Extraction Pipe Mount:

In an earlier post, I described a method of mounting the Extraction Pipe above the Roasting Chamber. At that time, the Pipe was simply allowed to rest on top of the metal grid (the only part I kept from the Top Filter); further, the balance of the space around the Pipe was closed by simply dropping a small piece of metal into place.

http://homeroaste...post_46167

Although the above method works well, I have since made improvements that enhance extraction efficiency. The revised method of mounting the Extraction Pipe atop of the Roasting Chamber can be seen in the attached photos. I am now using RTV to fill and close the space around the Pipe, and effectively eliminate any leakages.
ciel-007 attached the following images:
1_improved_extraction.jpg 2_improved_extraction.jpg 3_improved_extraction.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
 
RAG
I noticed the RTV on the front glass in a previous photo. What is the story with that?
 
RAG
Another RAF on the production line. I know it looks striking similar to a used first aide box.
RAG attached the following image:
raf2.jpg
 
ciel-007

Quote

RAG wrote:

... I know it looks striking similar to a used first aide box.


Rag, that's cool.
Have you decided to use a metal box for the Plenum?
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
 
RAG

Quote

ciel-007 wrote:
... decided to use a metal box for the Plenum?
ciel


Yes metal. Thanks for the input. First Aide box is near perfect size. Opens easy, and has a water tight seal. I debated painting it Camo or Red but decided on boring black. Should be roasting this weekend.

So where do you suggest to put the 165 override and tray switches? What would you suggest as next upgrade? (I put the air flow diverter, and temp monitoring as #1 and #2)

(btw...Why the seal on the front glass? )

Still porting my heater/fan control. Decided to try a netduino mini. Looking forward to getting back to that.
 
smico

Quote

RAG wrote:
(btw...Why the seal on the front glass? )

Hi RAG,
Your answer is here: http://forum.home...ad_id=2815. You should read ALL articles in Ciel's series "Enhancing My Hottop" series http://forum.home...rum_id=122
Those series became pretty much the Bible of the Hottop mods.

First aid kit is a great idea. i will have to look for one in Value Village.

Thanks,

Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
snwcmpr
If a First Aid Kit works, would you consider a nice lunch box with the Cartoon Character of your choice? I see them all over the place.

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

RAG wrote:

... where do you suggest to put the 165 override and tray switches? ...


Rag, I mounted the switches under the main control panel. That location makes it relatively easy to complete the modification, and very convenient to operate the switches during roasting.
ciel
ciel-007 attached the following image:
panel_with_advanced_mod_switches_1.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

RAG wrote:

I noticed the RTV on the front glass in a previous photo. What is the story with that?


Rag, I did not enjoy having to periodically dismantle the front cover to remove the unsightly chaff that gets wedged between the glass and the back steel panel. The high temperature silicone gasket works very well in preventing chaff from getting stuck, and reduces the need to remove the front cover to wash the glass.
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

Quote

smico wrote:

... those series became pretty much the Bible of the Hottop mods...


Miroslav, thank you for those kind words.

As you can probably tell, I very much enjoy tinkering with the totally amazing Hottop home roasters.

Further, I like to share the results of my experiments with other HT owners... hoping that it might help them explore new dimensions in roasting and possibly discover new levels of enjoyment...
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
 
RAG

Quote

snwcmpr wrote:

If a First Aid Kit works, would you consider a nice lunch box with the Cartoon Character of your choice? I see them all over the place.

Ken in NC


darn good idea. Would have loved a Road Runner or a Train.

Miroslav, thank you for all the help and pointing me in the right direction again. Seems I need to search these forums better.

Ciel, amazing as always.
I tried the new mod quickly and you were right again Ciel about having to redo my profiles. The fan at 75% after first crack really stalled the roast. Great to have this new tool o control the roast. I am of course using the default fan in the new enclosure. I also put a charcoal & wire mesh filter inn da box. I plan on cleaning up this mod more and carrying on with the switches and internals. I hesitate on the switches as it will be my first real no going back mod and I am considering a touch screen instead.

Thanks everyone for their help and support.

Rich
RAG attached the following image:
dsc01913.jpg
 
ciel-007
Rich, I too was hesitant about permanently mounting the switches below the Control Panel. So, during several weeks of roasting trials, I allowed the switches to simply hang below the Control Panel (as seen in the photo below).

It was not until I was satisfied with the performance of the switches, and the convenience of their location, that I proceeded to mount them permanently on the Side Panel of the Hottop.

However, should I ever change my mind, and elect to remove the switches, I can always order a new replacement Side Panel (Part # P-24) which Hottop sells for about $10.
ciel
ciel-007 attached the following image:
prototype_switches.jpg

Edited by ginny on 11/06/2013 9:29 AM
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
 
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
 
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