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View Thread » BUILDING A ROASTER » Drum Roasters
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Another electric 500g home roaster
After more than a year of using it :
With the true drum roaster it is possible to manage the roast, much easier than with Gene Caf, I used before. Very good results.
I prefered longer roasts, I couldn't say why.

E.g. Brazil 12.30-13.00 for FC was OK. With new coffee very bland. The same good results now I have with FC time 10-10.30
I have bought a cheap (~ 20$ ) Digital Grain Moisture Temperature Meter Tester from China. Now I know the reason : A humidity of new coffee is 9% , compared to old with 13%. ("old" is meant bought earlier)
The "drying phase" length must match the moisture of coffee. The rest of the roasting profile can be the same - it must match the bean an the taste target.
Very simple.
danst attached the following image:
The settings of the tester is 1 - wheat , it must be measured with pressure on the beans and probe.
A lot of time is passed...
The wrong ideas can be right after some time...
I made the additional 300W air preheating, as was earlier planned.
I use higher temperatures for preheating of the roaster. The sensitive beans can last out higher temperatures, only the heat must be added at the beginning. I had small defects with brazil beans by 180C preheating and roasting time about 15 minutes, with 210C and roasting time about 11 minutes - no problems, beans without any defects.
For better repeatability of roasts was my SW solution (in console) not ideal.
But the idea of Raspberry as a part of the roaster, without connecting to PC, this was right. I made new SW, in this case in Rpi native language : PYTHON.
The functionality is now as by other usual solutions. I can now compare multiple profiles.
I can use only small numeric keyboard and operate this as "roaster component". I like this simplicity, I am tired of mouse , this is my everyday job routine.
For smaller roasts I can switch off air preheating, and in every roasts it is switched off automatically at 170C - for possibility of cooling after FC.
The key for roasting is to achieve about the same preheating values - BT,MT,MET and then is repeating very easy.
For indoors conditions I have improved air exhaust. It was necessary, I make now more coffee, about 4kg/month.
danst attached the following images:
679.jpg ugly2.jpg ugly.jpg 671.jpg
It's good to hear you've got excellent control over your roaster. It looks like the preheating stage has helped get a jump on initial high heat needed at the start of a roast.

Have you found a favorite profile with this roaster that works well with most coffees intended for non-espresso brewing?

1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
I have the same feeling, the preheating helps. I make the coffee now closer to Raos principles. It can be right too, a perforated drum needs shorter roasting times. The profiles above are good for coffee with minimal acidity. I like it so for espresso. I usually mix (not overly traditional blend) 75% of this brazil ,up to 222-3 C, dumped just on hint of SC or close before , with 25% of colombian or nicaraguan coffee . This is roasted to 226, 20 sec in SC. It still preserves acidity and has no oils on the surface.
I drink moka or drip only on vacancy time, where I cant make espresso.
For this purpose, I make nearly the same coffee, I dump it about 5 degrees before. Sometime I give this coffee to a friends and they are very satisfied with it. But this is very subjective classification.
I know, when SC is about 223 C, the recommendation for non-espresso is dump about 208 - 210 C, but this works not for me.

I believe too, there is no universal profile (Im searching for), it depends on bean, roaster and taste preferences.
My profiles now generally meet 150 at 4 to 4.30 , FC 8-9 , end on 11-12.

Till I detect, it is wrong.
The roaster is now 2.5 years working, without failure and almost without maintenance. The key is to respect its properties. I am roasting now only 500g batches, for aeropress and espresso. It is easier to keep the profiles with constant load. The time has shown, the best are shorter times with higher preheating temperature. Close to Raos principles, but I prefer longer DTR (about 30%) for espresso. It can be caused by perforated drum and higher early RoR. Perhaps.
danst attached the following images:
santos.jpg sid.jpg u1.jpg

Your roaster and software look awesome. I'm not sure how I missed seeing your build earlier. Thanks for sharing. What is the source of your drum? Did you buy or build it?

Quest M3, IMEX digirosto 1500, various popcorn popper roasters, with TC4 logger, Quick Mill Vetrano, PIDed Rancilio Silvia espresso, Presso, Chemex, Hario, and Melitta drip, Cory and Yama vacuum/siphon, bodum french press, aeropress; Mazzer Major, Hario mini, and PeDe Dienes grinders - and a Nuova Simonelli Aurelia rebuilder in pieces
The drum is welded from 1.5mm peforated stainless.

Its funny, the drum, vanes and heating is very similar to new chinese Dalian Amazon 1 KG Roaster, DLA721. https://www.bella...aster.html
I have by contrast insulation and more Watt/kg ratio, but not the big mass of the front plate. And my one is more ugly!

The profiles above have greater DTR, it is by low airflow in winter cold days, with "Rao" style of roasting and very low ambient temperature. In this case is the heat transfer inside the bean probably lower and it requires more developement time. In better conditions I use more airflow and smaller DTR (25%).

So that I may to roast by the same way more beans as well as in winter, I decided to add another 600W heating element. I have had to do it directly.

For better control of airflow I use pressure detection in ducting (MPXV7002DP sensor, like this solution: http://www.home-b...34759.html) and I log now fan rpm and air pressure.
(The pressure can be used for functionality control: the duct is clogged or the damper is in wrong position)
600/200g Ugly roasters, "saturated" Bezzera BZ09, Fiorenzato Doge 63, Handground, Aeropress.
After improving and optimized setting of airflow on this roaster, it is easier to roast and DTR is now in usual range. On profile example the top blue and green "lines" are pressure in ducting and rpm of exhaust FAN . Simple PID procedure hold rpm constant, switching rpm is automatically according to BT or manually by keyboard or both.
Of course, the results are a bit better.
Yes, the heating has now 2200W (1600 original+600 new) + 300W add.preheating (for winter) and the drum is modified, for more mass. The optimal range is 500-650g, the absolute maximum, determined by drum volume is 750-800g. No more.
For larger loads was a motor upgrade necessary . The new one is industrial heavy duty DC 24V 45W, a bit overpowered motor. Quiet, no overheating, no cooling needed. Fortunately I bought a used item on for about 20 USD.
With switching supply I use 13-23V for 47-85 rpm . Basically, I use 50-70 rpm, dependent on bean type and load.
probably the last job on this roaster is to make the "prototype" electric equipment more decent.

But no worry, it stays ugly !
danst attached the following images:
motor_4.jpg prst.jpg ntopeni.jpg psantos.jpg

600/200g Ugly roasters, "saturated" Bezzera BZ09, Fiorenzato Doge 63, Handground, Aeropress.
It's all very nice. It's beautiful in it's function.
Quest M3, IMEX digirosto 1500, various popcorn popper roasters, with TC4 logger, Quick Mill Vetrano, PIDed Rancilio Silvia espresso, Presso, Chemex, Hario, and Melitta drip, Cory and Yama vacuum/siphon, bodum french press, aeropress; Mazzer Major, Hario mini, and PeDe Dienes grinders - and a Nuova Simonelli Aurelia rebuilder in pieces
Yes, it is nice in function, but at sight not. I finished new motor setup and new partial electricity wiring. Perhaps, it comes even some shielding of heating terminals, maybe.
Manual control is only on drum speed and cooling fan, of course basic on/off switching of electricity too. All other devices are regulated by SW.

But I have no possibility for better workmanship, however.
I am happy to manage full functionality, it is for me more important.
danst attached the following images:
newpower1.jpg control1.jpg

Edited by danst on 05/12/2017 02:26
600/200g Ugly roasters, "saturated" Bezzera BZ09, Fiorenzato Doge 63, Handground, Aeropress.
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