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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 Rao?s principles, but I prefer longer DTR (about 30%) for espresso. It can be caused by perforated drum and higher early RoR. Perhaps.

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Danst,

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?

John

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The drum is welded from 1.5mm peforated stainless.

It?s 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)

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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 ebay.de 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 !

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It's all very nice. It's beautiful in it's function.

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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.

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I am now familiar with this roaster, after 5 years of working without issues.
The repeating of profiles is easy .


But it?s time to say good bye....
The new larger toy is under construction completed ! :
https://forum.hom...ad_id=5918

And now, the Ugly_I has gone....