Just wondering, how is the inlet temp different than the ambient temp?
I've got a Huky with three probes BT, ET and MT just outside the drum. I know what the room temp is. Why would I need another probe?

I've been looking at Rob's Modulating Flavor... Has anyone bought it and compared it to the other coffee roaster books out there? I just hate buying a$50 book just to find out it's not really as good as Scott Rao's $45 book or some other book. Maybe this is another thread.

Inlet is going to measure how hot the air is pulled in from the heat source. I am curious if that will be hotter than MET at stable wormed up setting or cooler, I'm guessing hotter. ET is influence by the bean mass and the metal of the roaster and drum and ambient is just the room temperature. You could measure ambient in the TC4 if you have one. I don't know if Phidgets have that .

For the last roast I did, IAT was around 525F for the majority of the roast. MET 416F was at drop, with BT 402F. (Aida Batlle Selection, Finca Kilimanjaro washed)

ETA: As for the Modulating ... book - in summary, the author bought a small conventional-airflow gas drum roaster and did a whole bunch of roasts on it, and shows you the patterns that he observed. It isn't a "how to roast" book or "learn to roast" book or "this is how you should roast" book; it is a thin self-published work of what he found out over all those roasts he experimented with. It is a collection of his observations; not how you should apply those observations - that's up to you to experiment and figure out. For the right person, the Modulating ... work is worth many times the book's cost as a source of ideas; for the wrong person the work is worth little because it doesn't tell you what to do.

baldheadracing wrote: For the right person, the Modulating ... work is worth many times the book's cost as a source of ideas; for the wrong person the work is worth little because it doesn't tell you what to do.

THIS is exactly why Rao has been so successful. He explains a simple (not easy) approach to roasting that helps people learn how to control their machine. It is why I and many others have faithfully followed his advice.

Rob Hoos, on the other hand, is much more valuable to the roaster skilled enough in Rao's approach than he is to the newbie.

If you haven't checked out Rob's Iteration project, I highly recommend it https://www.iteration.coffee/

Thanks to Rao's books and classes and in a large part to the people here on HB, I can fully concur with Craig.

Disclaimer: While I wish I were lucky enough to be affiliated with either or both of these guys, I can unequivocally state that I am not and I have not been compensated for my comments here

Completely concur with both of you. Hoos literature is for a roaster with foundational knowledge, not for a novice. His is much more sensory oriented than Rao who is methodical and data-driven. Rao will guide you on how to get a defect-free roast while Hoos will help you find the flavor within those guard rails. Great set of works to learn from.

I just bought and skimmed this booklet. There's a summary at the back about what he found and what he suggests. His book, Modulating the Flavor Profile of Coffee also has summary tables of taste differences from varying lengths of time spent at different roast stages. Most of this current PDF is a discussion of Rob's thinking about tipping, what causes it, what others have said, and remedies they've suggested. He also reflects on changes to his earlier thinking about roasting. Essentially it's a discourse about what isn't completely known about coffee roasting and how one approaches greater roasting know-how.

I will have to tip Rob Hoos if this helps me modulate to roast better flavors in my product.

Here's the probe I fashioned:


And here's the temporary testing mount:



The motor must not be interfered with in spinning the drum so probably a drill-through will be the long term solution. But a more talented person may be able to mount a probe in better way against the back shell of the roaster.

Quite interesting to roast with that added insight. The slope rises quickly with airflow through the fan draw and stays quite more flat with fan off. Most of a roast done with the machine hot, the probe reads over 320 Candcdriftsvbelow 300 before drop at my typical gas settings, MET 215-40

I should study that pdf or othwrwise try to get an idea of best placement . Rather than 12 o'clock I had intended, the lower non-drilled mount is more like 6 o'clock and below the axis of rotation.

LBIespresso wrote:THIS is exactly why Rao has been so successful. He explains a simple (not easy) approach to roasting that helps people learn how to control their machine. It is why I and many others have faithfully followed his advice.

Rob Hoos, on the other hand, is much more valuable to the roaster skilled enough in Rao's approach than he is to the newbie.

If you haven't checked out Rob's Iteration project, I highly recommend it https://www.iteration.coffee/

Thanks to Rao's books and classes and in a large part to the people here on HB, I can fully concur with Craig.

Disclaimer: While I wish I were lucky enough to be affiliated with either or both of these guys, I can unequivocally state that I am not and I have not been compensated for my comments here

Thanks for the tip. I will check out the next iteration coffee. The upcoming one is on a Peruvian coffee sourced through catalyst trade, a project in Portland, I had heard of last year. And it will feature full city roast approaches, which I would like to plan and execute better.

For the first few (I have actually only done 2 of them so far), which were smaller, I asked him to send me some green along with the roasted and told him to charge me enough for it to be profitable for him. On this latest one I asked again while acknowledging that things may be too much bigger and busier. I haven't heard back yet but even without the green there is much to learn. His notes are insanely detailed. It's no wonder he is so good at his craft.