As someone who uses their Bullet to run a microroastery, I’m always trying to do everything I can to improve the quality of my roasts. Of course, this has led me to pour over Scott Rao’s books on the subject and apply his methods, which have been pretty good so far (with certain caveats being made since I’m on an electric machine, of course). I was thinking, why not hire someone like him to create a series of guidelines for good roasting on electric roasters? Even if it’s just an extended article and not a full book, I think having Rao provide a scientific analysis of the Bullet and how to maximize coffee quality on it would be extremely beneficial to every Bullet owner out there.
Rob Hoos hosts classes for the Bullet.
I am part of Scott Rao’s coaching club where he will analyse a roast curve a week. He is the roast guru - but doesn’t have lots of experience with the bullet. Obviously he knows how to read the curves etc.
So just working my way through. There we a few issues to start with - i.e. IBTS temps v. bean temps. Charging at 305c caused some concern until we figured that was about 210 BT!
Look here - still available seats on 25 September - you can easily get in touch with him for consultancy from his site. I have had several good discussions with him on roasting dynamics and temp sensors…
Hoos Bullet Classes
This brings up some interesting questions:
Does the Bullet probe temperature correspond to the probe temperature of other roasters? I frequently see FC temperatures from other machines fall somewhere between our bean probe and IBTS temps.
Is the Bullet’s probe somehow more insulated from the drum, so that it reads lower on preheat than other machines? Or should we really preheat to say 295C to achieve the commonly used probe preheat value of 200C?
Finally, putting temperature sensor comparison issues aside, If we develop a Bullet profile that matches the temperature curve from another roaster, will the beans cup the same? I’m pretty sure we don’t want to use the same curves as large commercial roasters.
It would be great to hear Rao’s or Hoos’ answers, but I’m also curious to hear what others on this forum think.
Have a good read here (by Rob Hoos):
Understanding the Limitations of Thermocouple Readings
This article is nailing the fact that you will never be able to compare anyone two profiles across roaster platforms (or even within the same) based on the sensor readings alone.
The IBTS, however, is bypassing the sensor artifacts from a normal TC or NTC probe and should be calibrated to reading the true surface temperature of the bean mass. This should in theory make us able to compare across roasters - even in the cup.
Great article. Thanks for sharing.
Good reply Steffen. The Bullet Bean Temp gets especially difficult with changes in drum speed as the probe position then varies relative to the center of the bean mass. Very difficult design parameter since the probe is in a fixed location. Makes the IBTS an appealing design solution
There are a couple issues that seem to be affecting the IR readings…
- contamination on the lens on the IR sensor
- what appears to be an aging process
Cleaning is just a maintenance chore and not a big deal. The latter item is just a guess on my part since cleaning the sensor hasn’t been able to restore the original values I was seeing in Jan 2019.
The aging that has occurred (if that’s what it is) could probably be resolved with calibration. But that requires a reference source, measuring equipment, and a means of adjustment. Owners are unlikely to have the first 2 and I have no clue what Aillio has in-built for adjustment (likely a calibration factor saved in f/w).
None of that should get in the way of roasting. I just stay aware of the changes in value and do some mental arithmetic to adjust for differences between what I see (the numbers, the color) and what I hear (1C, 2C).
Keeps it interesting!
Thanks for pointing out the Rob Hoos classes! I’d never heard of him before, and I’m happy to have a new source of knowledge. If any of you have taken his Bullet class, how advanced does it go? I’ve already completed hundreds of roasts on my Bullet and I’m looking to take my technique further, so an introductory level primer might not be suited to my current needs.
I took Rob’s Bullet class. It’s useful if only because it is specific to the R1. He covers a couple of techniques like “building a mountain” that Rao did not, in his more general class, which was oriented toward large gas fired roasters. I think Rob’s class was useful, worth the $$.
I am going thru his 2 videos on the Bullet now. They rent for $100 total, I think for a month. So far, so good. Worth a look. I think they cover some of the same stuff he will cover later this month.
On further examination, I see that I am watching the Intro to Bullet roasting videos by Rob Hoos, and the upcoming videos will be more advanced Bullet techniques. I will probably rent those as well. So far these are the most in depth Bullet roasting videos I have found anywhere online.
Where are you renting these from? On his site I see the classes themselves for $80 each, but I don’t see a separate rental option.
Thanks for the heads up on the classes, looks interesting!
Here is the link for the rental