Hi all,

Last week, our roastery received the long awaited Diedrich IR-12.  Now that it is up and running and a few roasts has been performed on it, I'd like to ask those who know this roaster a few questions.

1. What batch size do you usually roast on it?

2. What is your expected turning point time & temperature?

3. When and around which temperature do you "usually" get to your first crack?

4. What is your roast development time between first and second crack (or time you drop when you don't get to second crack)?

5. According to the Diedrich Manual, they recommend to have the airflow 50/50 at 280f and in the drum (80/20) at 380f, do you roast using these airflow settings?

I am asking these questions because I used to roast on a Toper 10kg, in batches of 6kg, and my reference points are kind of tied to this roaster.  I am also asking because I get astringency on some coffees that I didn't get on the Toper.  Also, some coffees (i.e. Kenya) seem less intense than they were on the Toper.

I tried batches of 6kg, 10kg and 12kg.  The problem might not be the load itself but the way to bring the coffee to first crack or even airflow settings.

Any hints or comments would be appreciated!


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Replies to This Discussion

Hi Kevin,


I'm glad to hear you enjoyed your training with Willem Boot.  He has published a lot of interesting articles on roasting and seems very knowledgeable on coffee.  I did my training with Mane Alves at Coffee Lab in Vermont.  We roasted both on a small Probat 5kg and a Diedrich IR-3.  However, I might try to attend to the "advanced" training with Diedrich sometime to better exploit our Diedrich IR-12.


When dropping at 385f, what are your batch size?  I rarely drop below 415 when roasting 9+ kg.  Then again, we might have a totally different weather :)  Also, at which temperature do you usually bottom out?  I usually get my turning point at around 165f @ 1:30.




Kevin said:

Thanks Martin!


I opted for the manual roasters so I'm working with "WC. I attended some of Willem Boot's courses in Mill Valley CA. Although he does not yet roast on a Diedrich for training purposes, his courses were a superb introduction to the art of roasting. 


It's great to find some roasters using the Diedrich machines on this forum!


Best of luck,



Hi Martin, so far most of my roasting work has been on the IR-1kg as I develop my roast profiles, so I'm using batch sizes of either 500 or 600grams (1.1-1.3lbs) - I found that smaller batch sizes make it difficult to get enough beans on the tryer to monitor roast progress. Bottom out temp with gas setting at 1.5"WC is usually between 175-184F which I usually hit at 1:20. Yep, I'd like to get the Diedrich's advanced training at some stage too, but it's quiet a hike to Sandpoint from the east coast of Ireland :) I've been there for the intro course and it was touch and go whether the flight from SFO would make it to Spokane due to fog...., so next time, I'll try and get there in the summer time.

Another issue that may effect your times and development is the altitude you roast at. I am around 7000ft., which effects batch size, airflow and finish times. Without as much air for the roaster, most of my roast finish between 16-17 minutes.

Yet on the cupping table, a nice African still comes across with tons of nice acidity and non of the issues you would expect with longer roast times. I guess it really all boils down to what you like, and how you personally choose to get there.

 Under the profile development section they suggest roasting at least 10 batches of the same coffee to zone in on the right profile. Have you tried this technique or do you have an alternate solution? I think I would be drowning in coffee if I used this technique on every coffee.



I roast on a Diedrich Hr-1 roaster, this is the electric type. In my user manual I dont have a  section called Profile Development. I would be grateful if you could say something about what Diedrich writes about this topic in your manual?



Hello Jorgen,

Try contacting Diedrich for a reprint on this section. If they will not email you a copy, I will attempt to get you the information. I have an IR12 and have never used the "profile development" as described above. I migrated from a atmospheric roaster so I had many profiles which I adapted to the IR12. Although Diedrich's technique looks like it would help narrow your choices, I also felt I would be producing too much coffee. My method while not very scientific is simple: I roast and cup. If I feel like tweaking, I will change it up looking for a better outcome. There are some excellent guidelines in this thread that should provide basic information. Hope this helps.



I have been in contact with Diedrich, and they simply cant find this section. Could you be specific about where this section is? Is it in the manual of the Ir-12, and wich year was this roaster produced. The guy that I have been in contact with at Diedrich would like to know more details about this section, that would give him a clue where to look:-)






Hello Jorgen,

Stephan Diedrich's approach to developing a roast profile can be found in the 'Roasting Workshop Summary' booklet which is handed out to participants of the roasting workshops held at Diedrich's facility in Sandpoint. It's a big undertaking to follow the procedure as outlined and it does require a lot of time (it says about 10hrs of roasting and cupping in the manual) and coffee, however its probably the most thorough description you will find of how to tweak your roast so that you bring out the maximum flavor potential possible in the beans you stock. Stephan is absolutely passionate about coffee and this approach reflects his philosophy that good coffee deserves this type of treatment.


You can find an outline of Diedrich's approach to developing a roast profile in the SCAA Library in a transcript from a presentation given at the 14th Annual SCAA Conference held in Anaheim in 2002. The presentation is entitled "How to Obtain Excellence with Drum Roasters" Use the search function in the SCAA library found on this link.


Hope this is some help



And there it was. Thank you very much. I even listened to the whole thing with Stephan Diedrich, Torrey Lee & Carl Staub. Would recommend that to everyone.


Kind regards,

Jørgen Mortensholm


Hi all,

Am I the only one on the planet having issues with a faulty PLC?!!!

3 weeks now this has been going on! Diedrich apparently has one 'qualified' tech as I was told! She's not in till 1 pm everyday this week as she's helping an Australian customer, and with 'the time difference'!!!..she won't be in to help other customers till 1 pm mountain time!!! What about other customers like me? Just a one of many questions I have for Diedrich at the moment!

She asked me to buy a new PLC 10 months ago when my graphics on my screen started acting weird while I was in a middle of a roast! I did. The PLC was replaced and I purchased a new one along with purchasing a new router etc. Now, it's happening again! This time she requested the PLC to be shipped to Diedrich! I did. She shipped it back saying it worked perfectly fine and there's nothing wrong with it! Now what? She said 'unwire and rewire PLC'. Did that too. Problem still there. All I can do is sit and wait till she's in at 1pm MT.

Apparently Diedrich decided to switch to a new operating system a couple years ago, as Microsoft refused to support the old system any longer. My roaster is R12 and 4 years old. New system costs $5000,00 +$1500,00 cost on top of that for a techie to install it as they told me, + travel time etc !!!

I'm trying to breath. It's just frustrating.



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