Back to Back on R2 - switching roasts/beans

I’m new to roasting - completed about 12 roasts on my new R2. The question is, if i’m running a playback of a roast that i have in my stash from Roast World and i want to do back-to-back but the second roast is a different bean from a different playback; how do i do this? Thanks Jason

Hello,

I have about the same experience on my R2 Pro so I am by no means an expert, but what I would do is start the preheating after Roast 1 and then click on the thunderbolt symbol at the top right of Roast Time. There, you can cancel the playback of Roast 1. Afterwards, just start the recipe or manual roast of Roast 2 all while your machine is preheating.

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Thank you. I tred that and it seemed to work just fine :slight_smile:

I’m experiencing a different thing when I’m doing back to back roasts, using same bean, same batch size & same recipe, the 2nd roast is always faster. And slightly different when cupping as well. Curious if you guys are experiencing the same thing? And if there are any suggestions to try and be as consistent as possible when it comes to back to back roasts? Thanks

Is it just the second roast? Meaning if you do 3 roast or more are all the roasts the same apart from roast 1? I would guess that may be the case. What i do is when the roaster is up to temp i let it hold in the ready state for at least 10 mins but usually more like 15 and then i do my first roast. This gives me consistent roasts.

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You must preheat your machine longer for the first roast. The bean probe temperature is the main indicator here. The last time you were roasting, you’ve started at 148.9°C on the bean probe for the first roast, and at 154.3°C for the second. That is why the second one is faster. Preheat longer for the first roast, or increment your PH temp for that one. In any case, keep your eye on the BT and charge a couple of minutes after you’ve reached the desired temperature.

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I have not tried 3 or more back to back roasts using the same recipe yet. Will do that and monitor what the changes are between each roast.

I normally would put the beans in once it says charge, do you mean you leave it for an addition 10-15 after it says charge? And do you do that for every roast? or just your first? Thank you

To expand on what Braca posted above…

The IR detector reads drum temp via IR radiation while the probe reads the bean temp directly via conduction (direct contact). What isn’t obvious, however, is that the probe, being mounted directly to the front plate, is greatly influenced by the temp of that mounting surface. The drum gets to temp rapidly as it is being heated directly via the induction heating. Nothing heats the front plate except the roasting beans and (before charging) radiated heat from the drum. To have even-heating throughout the roaster interior during the start of a roast you must also preheat the face plate as well as the drum. That takes a long time as the heat source without beans in the roaster is radiated heat from the drum hitting the interior surface of the face plate where the bean probe is mounted. If the front plate isn’t up to temp that will throw off the profile of the first roast.

There are a couple options-

  • do a throw-away roast after hitting the Charge announcement. That will get beans up to temp which will heat the otherwise unheated front plate. Clearly you will want to use junk green beans- not the good stuff you want to brew! Even so it’s an expensive way to preheat.
  • alternately you can extend the preheat long after Charge is announced. In this case you will monitor the bean probe till it gets close to the same preheat temp you see at the start of a 2nd or later roast (before charging).

In my case I extend the first-roast preheat till the bean temp (the probe) hits something over 290°F/146°C (basically when my patience runs out!). That first roast profile isn’t exactly right compared to later roasts but it’s close. Enough so that I can’t notice a great deal of taste-difference between it and the later roasts.

Bruce

Edit- I’m roasting on a vintage roaster (circa 2019). No clue how that compares to the new R2, so if that’s what you have then ymmv. I’ve made the assumption here (always risky!) that the preheat on the new R2 is similar to my vintage R1.

Edit 2- I preheat to a lower temp (419°F/146°C) than many of the users here on the forum.

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yes exactly, i only relied on the IBTS temp without taking into consideration the drum temp itself. I would compensate by start the taper in power earlier to achieve a similar roast, which I did somewhat achieve but when cupping I am still able to tell the difference. So will definitely be on the lookout and keep an eye on the drump temp. Thanks a lot for the advice

That makes sense, thanks a lot for the detailed feedback, and yes I am using the R2 pro. I think my plan is I will let it sit a couple of minutes once it says charge, keeping an eye on the drum temp, and the same for my back to back roasts, will aim to have the same or similar drump temps at drop. Thanks again

for the first roast only once the roaster says it’s ready to roast i leave it for another 10-15 mins maybe 20, so the whole unit is infused with heat. Then i start roasting and go back to back without a delay.

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It will probably take more than a couple minutes. It takes on the order for 20-30 minutes for my face plate temp to go from about 245°F at Charge to about 290° F at my Preheat setting of 419° F. If you’re Preheating to a higher temp it may be faster but I’d suggest you go by the temp readings rather than an arbitrary time allowance. The thermal path is not sufficiently direct for rapid temp change of the face plate during Preheat.

Bruce

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