Well this is pretty slick...

I just roasted a bunch of coffee. To try to keep the roasts consistent using what RT3 (the roasting software) refers to as Recipes. Recipes are a set of button pushing commands to the roaster that can be based upon Time (the default) or Temperature AND Time (that's the logical AND meaning both). They provide consistency that seems to be lacking when I just follow the button pushes of an earlier roast. Easy-peasey. But the results have been inconsistent and I end up with roasts that have a graph that varies a lot. And I mean a lot.

Thru some odd accumulation of good fortune I did a roast that seemed to have all the right shapes to the curves that are recorded during the roast. At the same time I needed to answer a few questions from the software developer about how the Recipe feature works in RT3. So...

I decided to create a new version of the Recipe using the roast that had come out *looking* like I wanted. But instead of using the in-built roast-to-recipe conversion which is mechanized in RT3 using Time, I instead used the temperature values from the IR sensor (part of what the mfr calls the IBTS) that occurred near each power, fan and drum speed control setting I had used. There's nothing earth-shaking here: users have been doing this to one extent or another from the git-go. I just hadn't tried it myself. Well that whole approach has definitely opened my eyes! 

Here's a list of the steps that's a Copy/Paste of what RT3 saved as a Recipe. The Time values are pretty much meaningless- they just have to be =/> 5 seconds.

• Preheat Temperature = 392.00 °F; Preset values = P4, D4, F2 [Initial settings]
  
• IR Temp >= 180.00 °F AND Time >= 0:00:05: P5
• IR Temp >= 210.00 °F AND Time >= 0:00:05: P6
• IR Temp >= 240.00 °F AND Time >= 0:00:05: P7
• IR Temp >= 260.00 °F AND Time >= 0:01:00: P8, D5
• IR Temp >= 280.00 °F AND Time >= 0:01:00: D6
• IR Temp >= 300.00 °F AND Time >= 0:01:00: D7
• IR Temp >= 328.00 °F AND Time >= 0:01:00: P7, D8 (Msg- YP=330.00°F)
• IR Temp >= 350.00 °F AND Time >= 0:02:00: F3
• IR Temp >= 352.00 °F AND Time >= 0:02:01: F2
• IR Temp >= 375.00 °F AND Time >= 0:02:01: P6
• IR Temp >= 385.00 °F AND Time >= 0:02:01: P5
• IR Temp >= 397.00 °F AND Time >= 0:02:01: (Msg- 1Cs) 
• IR Temp >= 401.00 °F AND Time >= 0:02:05: P8
• IR Temp >= 413.00 °F AND Time >= 0:03:00: P5
  
• IR Temp >= 421.00 °F AND Time >= 0:03:00: F3
  
• IR Temp >= 423.00 °F AND Time >= 0:03:00: P4
  
• IR Temp >= 430.00 °F AND Time >= 0:03:00: P3
• IR Temp >= 441.00 °F AND Time >= 0:03:00: P4
• IR Temp >= 444.00 °F AND Time >= 0:03:00: (Msg- 2Cs)
• IR Temp >= 449.00 °F AND Time >= 0:03:00: (Msg- End Roast at 449°F) 
  
  

This Recipe is in finer detail than anything I've done simply because I have no idea what it takes to make the temperature rise with a smooth, gradual curve without wildly punching power, fan & drum speed buttons (which works about as badly as you can imagine). It seems inappropriate to flail around with roasts till you stumble upon something that looks 'pretty' but that's what I've done. And now I have at least a dozen roasts using this set of instructions - this Recipe - and it seems to be very repeatable. 

So... Bingo! I have my first working Recipe that isn't 'pretty close'. With something like a dozen roasts this has been very repeatable. And that is a first for me. What seems to vary a little is the duration of the roast. I'm guessing this relates to ambient temp in the shop where I roast as well as variations in starting temperature (IR temp and bean probe temp) when I add the beans.

And yes, the Chiapas coffee from this Recipe tastes great!

 

Here's a roast done with the recipe and is pretty much like the others that were executed in the same way...