Twin heat source KKTO roaster

[Koffee_Kosmo]

Thanks Paul. I'll take some measurements and see how far away I am but I think I'm probably well over 30mm. I guess I thought that your standard volume of 7 to 9 liters didn't necessarily apply because of the booster heater but if you say it does I believe you. I guess I thought that the roaster volume had to do with the available heat for a given volume. For my own understanding, can you please explain the how and why of the ideal roaster volume of 7 -9 liters?

Rob

Hi again Rob
it is correct that the volume has been calculated based on the available heat of the Turbo Oven
The speed of heat delivery and retention of heat inside the roast chamber is another story

The second heat source will allow for larger batches to be roasted by equalising and boosting the available heats parameters
It evens out the fan-forced heat applied on the roasting beans so the heat doesn't fluctuate up and down giving you an easy climbing heat curve to FC & SC

So the current volume parameters still apply until one exceeds the available heat watts X 2 fold

KK

[badhabitroasters]

Thanks Paul. I'll take some measurements and see how far away I am but I think I'm probably well over 30mm. I guess I thought that your standard volume of 7 to 9 liters didn't necessarily apply because of the booster heater but if you say it does I believe you. I guess I thought that the roaster volume had to do with the available heat for a given volume. For my own understanding, can you please explain the how and why of the ideal roaster volume of 7 -9 liters?

Rob

[Koffee_Kosmo]

Element height should not be to low @ Ideally you should aim for about 30mm or 1.5 inches distance for BROWN beans
One must allow room for bean expansion
Also aim for a roaster volume of 7 to 9 litres you could go down to 6.5 litres but thats best for consistent larger batches only - 8 litres is a good all round any size batch volume

KK

[badhabitroasters]

In preparation for a TC4 Shield based control system, I've disabled the T-stat on both of the heating elements and am currently controlling on/off of the heating elements via toggle switches on the front panel of my roaster. The toggle switches are controlling a pair of SSRs. My buddy and I are in the process of building an Arduino Megga / TC4 controller that will replace these toggle switches. I may have to reduce the height of the spacer that forms the side wall. I can generate enough heat but I think I may want the C/O element to be closer so that I get more effect from the CO heat and the skillet being more of a booster as other people have suggested. I think I understand a little more of what Paul from Koffee Kosmo was getting at when he talked about volume. I was thinking that since I was aiming for a little over 1 kilo (2 pounds) of roasted coffee and since I had an additional heat source, I needed (and could get away with) the extra volume. I probably overdid it. I think the result is that my CO is a little too far away from the bean mass. It will be work but I plan to cut the height of my chamber down. Can you tell me how far your element is from the bean mass? My last roast started with 544 gr., lasted 13 minutes (after preheating to 280 F). 1st crack started 10 mins. into the roast, I pulled the beans out after 1st was fully stopped but 2 hadn't started. The taste (Colombia Pedregal Vereda Agua Blanc) was good but not the best I've had. I think I backed off the heat a little too much after 1st crack started.

I have been gathering information to build this roaster from 4 different forums and I'd like to share what I've done so far but not sure the best way to go about it. I'm not exactly what you'd call a "power user". I'll probably just post the documentation to one site and let everybody else know where to find it if they're interested. I'd be happy to hear comments from anybody who may have something I can learn from.

Rob

[Mono]

Rob I will be very interested in your results, please keep us up to date with your progress.

Steve

[Koffee_Kosmo]

This is my 2009 drawing of the DIY Twin Heat concept, using a combo of DIY and off the shelf products
Correct roast chamber air volume is is important




KK

[badhabitroasters]

My dual heat roaster was up and running but is currently down again as I convert the elements on both the electric skillet and the TO to run on toggle switches and SSRs instead of the t-stats. I'm currently roasting with my original SC/GG as I make these mods. The end result will be a dual heat unit being controlled either manually via buttons or knobs or with a PID system running through an Arduino with TC4 shield and either Kona or Artisian_PID software. I hope to make a trial roast tomorrow. I wanted to be able to end up with 2 lbs. of roasted coffee so the size of my roasting chamber is pretty big. I'm concerned that even though I have a dual heat source, my convection oven element may be too far away from the bean mass. If my roast tomorrow still takes too much time to complete I'm afraid that I might need to take some of the height off of the chamber walls and get the beans closer to the element. We'll see tomorrow.

Rob

[bolb]

Hi All
Haven't posted on CS for a while now so thought i would pop on for a look.
A very interesting thread, personally haven't needed to use a 2nd heat source as a Halogen TO is sufficient for me.

You guys amaze me with your ingenuity and abilities to fabricate

I am on my 2nd KKTO from KK, well you have to have a spare don't you?
I have done over 650 roasts now and generally do 950g of green every roast and the consistency of roast is always good and the outcome in the cup is superb.

I am intrigued by the 2nd heat source though so i think its time for a play with the original beta tester unit.

Mal

[Koffee_Kosmo]

KK, I started this after you told me about the plans you had. I believe that this is the machine that "Derrelix" has posted info on. Is that right? Can you tell me the width that my agitator would be if I got 2 of your single blades and bent them into the same shape as a double would be?

Yes its the one derrelix built

Please see the uploaded drawing
The agitator works best with the diameter measurements noted on the perforated insert

KK

[badhabitroasters]

Its already been built
I had all the parts to build the frypan as a second heat source for KKTO design
Decided to gift the whole system to another home roaster to compete the build
That was last year and its working extremely well

KK

KK, I started this after you told me about the plans you had. I believe that this is the machine that "Derrelix" has posted info on. Is that right? Can you tell me the width that my agitator would be if I got 2 of your single blades and bent them into the same shape as a double would be?

[Koffee_Kosmo]

Hi, similar idea to what I threw around some time ago. Never got around to trying it.......life gets too busy sometimes. :-(. I like it as it will spread the beans over a greater area & bring the heat source[s] closer to the beans which should shorten roast times. The bit that I believe could be problematic is the stirrer blade. KK's I feel would be too short [without mods] to properly mix the beans towards the outer edges of the pan/skillet.

Steve

PS. if you go ahead with the idea please keep us updated I for one would be very interested. This may even prompt me to look at the concept again.

Its already been built
I had all the parts to build the frypan as a second heat source for KKTO design
Decided to gift the whole system to another home roaster to compete the build
That was last year and its working extremely well

KK

[Mono]

Hi, similar idea to what I threw around some time ago. Never got around to trying it.......life gets too busy sometimes. :-(. I like it as it will spread the beans over a greater area & bring the heat source[s] closer to the beans which should shorten roast times. The bit that I believe could be problematic is the stirrer blade. KK's I feel would be too short [without mods] to properly mix the beans towards the outer edges of the pan/skillet.

Steve

PS. if you go ahead with the idea please keep us updated I for one would be very interested. This may even prompt me to look at the concept again.

[badhabitroasters]

After talking via email to Paul from KK, I am putting together hardware to build a dual heat roaster that I can roast from 600 to 1200 grams of green to yield a pound for me and a pound to give or sell to friends. I'd love feedback from anybody regarding my plans. I'd hate to get going on this and find that I've made some bad assumptions. I'm in the U.S. so some of the things that are common for most of you are not quite so common here. I've been roasting for about a year now using a Galloping Gourmet convection oven and a modified Stir Crazy popcorn popper. This has been good for learning but it sounds like my motors about to give up so I'm on to bigger and better. I plan to use a Stainless steel 12" (30cm) electric skillet, a spacer to extend the skillet wall as needed to achieve the height necessary to accommodate a stainless steel bean basket (strainer) that is about 10 cm tall, 28cm in diameter and has rounded sides with a 13cm wide flat bottom. The GG convection oven is the same diameter as the electric skillet. Paul from KK has suggested that I could use the wire wisk type agitator but I'm hoping that I can can use his agitator just because it's so sexy. I'm planning to leave a 1 -2cm space between the skillet and the bean basket to disperse heat and allow for chaff collection. I'll probably use a windshield wiper motor to drive the agitator. I'll insulate the sides of the skillet and spacer and seal the spacer to the GG with silicone hose. I plan to fit it with a monitor / control system later. Thoughts anyone?

[Mono]

I see that this is an old thread but I was wondering if you are currently using this roaster. This is similar to what I'm thinking of building and was just curious if the final form is in use?

Yes, still use it weekly in the same configuration. One day I will change the lower element to one from an old bread maker as I feel that will cope better. Keep us posted on your slant to this.

Steve.

[badhabitroasters]

I see that this is an old thread but I was wondering if you are currently using this roaster. This is similar to what I'm thinking of building and was just curious if the final form is in use?