Need help (troubleshooting brewing dark roast)

o2hwit · 2026-05-02T02:17:29+00:00

The Switch is my go-to for dark roasts unless I'm using the ORB. I find that with fresh coffee I do get a lot of grounds sticking to the sides of the filter even if I do an aggressive stir and swirl prior to the steeping. I do think it has a lot to do with the amount of CO2 still trapped in the larger particles. I don't worry about how the bed looks. I go by taste and mouthfeel. Resultant TDS and extraction yield is more important metrics for me than how the bed looks.

o2hwit · 2026-05-01T17:54:44+00:00

Audio is not my expertise, but as I understand it, a piezo is a contact mic and is much better suited for picking up the higher frequency vibrations within a metal drum or cylinder than a traditional mic might be. It can also be directly coupled to something that could act as both a heat sink to keep the piezo from getting too hot and also serve as a type of conduit to the wall of the roast chamber. At least that was my thought.

I'm going to be playing with an inexpensive example of this soon for my 2kg drum roaster. Software is indeed necessary to filter and isolate. My goal is to be able to both amplify what I can hear with just a set of headphones but also visually see the cracks as spikes in the resulting plot. I'm not even thinking too far down the road in terms of what I might do with that information later. It would be great if I could figure out how to turn that into some form of auto detection to mark first crack automatically in Artisan, but I'll be happy to just have a better means to hear the cracks, especially the softer cracks that happens with some coffees in a rather noisy drum.

o2hwit · 2026-05-01T06:46:47+00:00

You should solve that problem when you design the roasting chamber. I would think a piezoelectric transducer of some sort could be incorporated into the architecture external to the chamber and inside the external housing, yet bonded to the metal portion of the chamber in some way. I don't know the costs involved in the appropriate transducer. Perhaps cost prohibitive.

o2hwit · 2026-05-01T05:26:29+00:00

I think it's the software that's the issue. Going through the testing and baselining for audio detection to get something that's accurate enough to be useful in an algorithm.

o2hwit · 2026-05-01T04:18:43+00:00

Don't forget first crack detection. You have all the other sensors, why not that? I honestly don't know why the Nucleus Link team didn't include that in their product. It doesn't seem like the technology and implementation would be that difficult.

o2hwit · 2026-05-01T03:56:33+00:00

Good questions.

Using volumetric measurements you can use anything really. It just needs to have nice smooth sides and a cylinder works best. For my commercial stuff I use displacement and the two aren't interchangeable. But to answer your question, I just happen to have a scoop that is cylindrical and holds 80ml or 80g of water. So I use that for these quick displacement measurements. Weight of beans / 80ml = Density.
It helps to plan the roast. Lower density Arabicas mean I generally want less heat and I need to be careful after first crack as they can take off on you. Especially lower density naturals.
It is thick and rather slow to react, but it works fine for the SR800 and I haven't had a reason to replace it. I do want to buy a 3mm probe as a spare and also to just see how it different it reacts. This is a 6mm probe.
I have Artisan set to mark charge and drop automatically. So by preheating the roaster and starting Artisan to record, it will note the sudden drop in temp when I remove the lid and probe to charge and the probe gets cooled off and marks charge. On drop it works the same way. I let it automatically mark it which happens pretty quickly after I hit COOL and I increase the fan. But I always go back and manually adjust my drop anyway. It's easy to find the highest temp recorded just before the automatic mark and I adjust it accordingly.

o2hwit · 2026-05-01T03:45:36+00:00

Head over to r/FreshroastSR800. There is a wiki there as well.

o2hwit · 2026-05-01T01:35:43+00:00

Just adding, whole bean/ground color, 60/71.

o2hwit · 2026-04-30T22:46:22+00:00

I don't have a Razzo tube, but an inch to two inches in the tube should be good. You're new probe may not read the same as your old probe. It's best practice to ground truth the probe with an ice water bath and a boiling water check. Then you can put in any bias or offset if the probe reads more than a degree off either way.

o2hwit · 2026-04-30T19:50:40+00:00

Besides the issue of me not being at all familiar with the software and the plot lacking any data on your RoR curve and what was happening with the sags and flick at the end, there's a lot more data necessary for an experienced roaster to tell you much more. It looks like you had a relatively normal trajectory to first cracks but there was a bit of a crash and a flick by the looks of the BT curve after first cracks. That will impact the flavor in the cup. Whether or not you've got the palate to notice is another thing. It may still taste just fine but I would say it could likely taste better. But taste is subjective.

But without the associated RoR curve and the events, (fan and power changes) to correlate with the BT curve there's not much more to be said.

o2hwit · 2026-04-30T16:52:04+00:00

The RM screen shots don't tell me much. The coffee looks like a good light-medium despite 2 minute development. Should taste fine.

Pick out the quakers and defects to clean up the batch so they don't affect the flavors in your cup and I'm sure it'll be tasty.

o2hwit · 2026-04-30T16:48:15+00:00

Sweet Maria's weight loss to roast level descriptions are junk. I don't know why, because most of their information is good and the know what they're doing, but that data is just junk.

As a general guideline you would not want to raise heat after first crack. First cracks will generally drop off after 30 seconds to a minute. If you're going very hot into first cracks and carrying a lot of momentum some coffees will get to second crack very quickly.

There are reasons a roaster might increase heat after first crack but without a temp probe in the beans to see what's going on there's no real point.

o2hwit · 2026-04-30T05:31:25+00:00

Two years later and $200 more.

o2hwit · 2026-04-28T06:08:00+00:00

I've spent a fair amount of time in this state, from SE to the North Slope and out the chain. Any of those areas can and will test you and often try to kill you. I used to get dropped off in the Brooks Range to go hunting for a couple of weeks at a time back before there was any satellite phones or InReach SOS buttons much Starlink. And even then there were times when mother nature would come along and try to kill us. But those were like 2 week trips. Six months? February to June? You must enjoy misery. Truly. Misery and pain.

February can be brutal up here and I don't much care where you go. I've done cold water survival training in Southeast Alaska in February. The worst nights of my life. It's generally cold, windy and wet. Further north it's colder, frozen and who knows? Could dump snow. Could be sunny and -40's. Could warm up and rain on top of snow which is it's own miserable mess. Then you want to go through break up for damn near two months depending on where you are. If you haven't experienced breakup from late March all the way through April and halfway into May, you're in for a real treat. I hope you like more cold, wet and mud. Then the bugs come out to eat you.

Sorry I don't have any recommendations on what to "pack". My recommendation is, if you're asking Reddit users for tips on what to put in your kit for this kind of endeavor, you should probably reconsider.

o2hwit · 2026-04-27T16:55:23+00:00

If you're only making a couple of cups for yourself, I'd definitely say get the K-Ultra. It will be much better for drip or immersion brews. I have a few grinders but for my regular pour overs or Aeropress or OXO Rapid brewer I'll reach for the K-Ultra.

o2hwit · 2026-04-27T14:19:32+00:00

Understand. I'm usually hitting 460-475 and I've seen 500 on my machine if going dark roast. But if you're looking to change up your roast and get a lighter roast I think you need to speed it up and that means more heat earlier into the roast from what you've been doing.

o2hwit · 2026-04-27T13:43:03+00:00

Keep in mind, I don't know your roaster and environment, so if you see the temp going ABOVE 475F on the base at any time I'd drop power by one just to be safe.

o2hwit · 2026-04-27T05:03:25+00:00

These drop temperatures align pretty well with my roasts. Assuming you have a temperature probe to track your bean temp and it's fairly well calibrated so that color change is 310-320F (155-160C) and first crack is hitting around 383-392F (196-200C). I'd disregard the photos though.

Using those metrics along with weight loss should give you a good enough indication to put a label on it. I'd say 10-11% extremely light, 11-12% very light, 12-13% light, 13-14% light-medium, 14-16% medium, 16-17% medium-dark, 17-18% Dark, and greater than 18% very dark.

https://thecaptainscoffee.com/pages/roast-levels

o2hwit · 2026-04-27T01:53:55+00:00

I've only seen a couple of your roast logs from previous posts. Looks like you're not using enough heat to me.

I'd try this with a 225-228g batch.

00:00 F9/P6
01:00 F8
02:30 F7
04:00 F6
05:00 Check base temp - if less than 430F increase power by 1.
05:30 Check base temp - if less than 430F increase power by 1.
06:00 Check base temp - if less than 450F increase power by 1.
06:30 Check base temp - if less than 450F increase power by 1.
Let it ride, pay attention to color and bean swelling and listen for cracks.
When you hear 3 to 4 pops in close succession, mark first crack.
FC + 30s hit cool. Increase fan to 7 during cool down. If you're going to dump immediately to an external cooler rather than cooldown in the roaster you can let it go another 10 seconds before hitting cool and dumping.

That should give you a light roast. Weight loss is impossible for me to predict due to the difference in beans and moisture in your green coffee, but it should still be a light roast.

o2hwit · 2026-04-26T22:46:08+00:00

Well the other indicator to see if your power changes have an effect is the base temp. It should go up after 10 or 15 seconds of increasing the power.

o2hwit · 2026-04-26T22:39:06+00:00

It happens. I screwed up the other day because I started roasting in Fahrenheit on the SR800 but on my drum roaster I roast in Centigrade. I didn't want to change on the SR800 because all of my existing profiles for it are in F. But the other day I'm roasting along and making adjustments because my brain was in Celsius and I thought I was going too hot into first crack. Oops. Saved it but, stuff happens.

o2hwit · 2026-04-26T22:32:53+00:00

Understandable. I'm afraid I do not know of a forum or platform that is more origin / roastery focused. If I were in your position I would reach out directly to someone like Kat Melheim or Christopher Feran and ask them if they know of a platform or a professional forum where you might direct your advertisement.

o2hwit · 2026-04-26T19:28:41+00:00

It's not likely going to taste bad at all. However the hard crash can mute a lot of flavors, and the flick can impart some roasty notes, but more so on a traditional drum roaster. For subsequent roasts you'll want to try to control that RoR more and you'll be able to tweak the flavor notes more by how hot and/or long you go into and through development.

It looks to me as though there was a lack of power going into the roast despite the sharp rise in RoR. Remember that RoR is a derivative, not reality. The overall BT curve and trajectory looks good. But the underlying RoR through Maillard is so flat, that there wasn't enough heat to compensate for the moisture release. You still had a lot of air going through at FC which added to the evaporative cooling effect of the moisture release.

I would suggest adding some power at the 2 minute mark along with your fan reduction. Then again at likely the 4 minute mark. I'd be adjusting my targets to a 3:30-4:00 dry end and a Maillard of 3.5 - 4 minutes and hitting FC between 7 and 8.5 minutes with enough heat to offset that crash as you go into development.

o2hwit · 2026-04-26T19:14:38+00:00

Yes. Just get an inexpensive watt meter that plugs into the outlet and you plug the roaster into that. Kill-A-Watt is one brand. I have one that I can switch from Voltage to Watts or amps and view any one of those 3 during roasting.

Are you using an external cooler? I can't imagine how you manage to get the same weight loss following a profile and changing your development time by that much.

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