There has been a lot of interesting discussion on profiles lately. One thing to consider is that every roaster has a sort of "Inherent Profile". For example, my homemade 57 ounce roaster has a straight line profile that yields a roast in about 20 minutes. I should rename the thread 64 ounce since that's my normal batch size nowadays.

Making Your Own 57 Ounce Roaster Updated Again

That inherent profile doesn't require me to do anything to adjust temperature. That's because I:

1. Always turn up the gas to full.
2. Always start with a cold roaster.

What is happening is that starting with a cold roaster means I automatically get a slower ramp of heat which is my "drying phase".

Then the heat climbs basically in a straight line until I dump the roast. At around first crack I can delay the onset of 2d crack by either removing the hood (dumping heat) or reducing the flame. I've found that removing the hood is just perfect.

Things that will have an impact on the above include roasting small amounts, but don't include ambient air temperature in my area. It is true that the ambient temperature at my house might have some impact on the roast, but it turns out that it doesn't have a huge impact. My summer roasts might be a bit faster than my winter roasts, but not by much.

I guess all roasters have an inherent profile assuming that one starts with a cold roaster or a roaster at a known temperature and known charge. The beauty of understanding the roaster, at least in my case is that there really isn't much to do -- no need to ramp fast, slow or anything. The roaster roasts, ramps naturally and then the real skill is knowing when to stop.

On the 2kg gas drum roaster that I use it is as simple as you say, and only requires choosing the right starting temperature (or achieving the right 'bottom-out' temperature if roasting continuously), then changing the airflow from drum+cooling mixer to only drum at 1st crack to lengthen the roast.

Here is what it looks like-

If you just look at the bean temp you can see a gentle and even rise after bottoming out. The only two factors are turning on the gas (1.5") and changing the airflow (at 1st crack).

I would infer that instead of having an easy roaster, you have one that gives you little control.... like a train on which you just wait for your stop. If that's all you want, then simple enough. In fact, it can be overwhelming to have an almost infinite realm of possibilities available when (mostly) smooth and steady is what's best for the cup.

My point was that left to it's own devices every roaster has an inherent profile. That profile may be good or bad, but for some roasters that don't have a good inherent profile, you will spend your time changing and in some cases fighting it. What determines this profile is your heat source the things the roaster is made of.

For example if the drum is heavy steel it won't shed heat very fast, so perhaps starting from a hot start is the best way to go. Mine is thin stainless, so it is more responsive to heat gain and heat loss. That's good for me but wouldn't be so good for someone roasting all day and wanting to drop beans into a hot drum. I normally only roast two batches and purposely let the drum cool as I do a few things to the batch that just was roasted. By the time I'm ready for batch 2, the drum is cool enough to touch.

With my roaster, as humble as it is, adding heat is not the problem. If I made it hotter it would not be a beneficial change. But allowing for heat reduction at certain points and even bringing the heat back up is all possible.

In my case, I often lower the heat after first crack, not by lowering the flame, but by taking the steel hood off. This allows me to alter the inherent profile by flattening the curve (which was linear) and thereby prolonging the time before 2d crack.

In any case your analogy to a train fails because by the time you get to the station (2d crack) it's too late to get off!!!

Roaster variables are:
Bean mass
Roaster mass
Airflow
Heat

Roaster mass is fixed, but where the other three are decided on being, even in a fixed condition, results in an infinite number of possible profiles.

So there is no such thing as an inherent profile for any given roaster.

I do personally try to fix as many variables as possible to achieve the profile I'm going for, since smooth and steady is generally the goal. However, all my profiles require dialing in throughout the roast.

I'm curious about your roaster. Can you go into details about it?

It's a 6kg Neuhaus/Neotec inspired rotating fluidized bed hot air roaster. It's about 60lbs of stainless and burns at about 50kBtu. I roast about 1,000lbs (100 roasts) per month on it. My coffee is as close to fruit juice as I've ever tasted, which I attribute to being able to control the roast through very precise profiles.

DJR wrote: ... inherent profile doesn't require me to do anything to adjust temperature.

endlesscycles wrote: ... there is no such thing as an inherent profile for any given roaster.

Some of this is just the semantics of "inherent." Since entelechies are a bit out of date, there's not much point discussing what roasters (machines) want. But what roasters (people) want is more interesting.

Any roaster can be run in a set it and forget way. For a shop drum roaster, this may be a fixed preheat temperature, a constant par heat and airflow rate, and a par amount of beans. For an unstable commercial air or convection roaster, this may be a setting on its automatic controls that keeps it to the profile that the design engineers had in mind.

Is there any roaster where this procedure always gets you the best tasting roast? I doubt it. But there are other good reasons to have set it and forget it roasters. For cupping, you want a fixed roast level and speed; so a highly stereotyped roasting profile is exactly what is needed. Companies like Diedrichs specialize in selling drum roasters to people just starting out, and they have an SOp that creates enjoyable but not too edgy or adventirous roasts -- exactly what a person starting out wants.

Of course, I've seen a lot of Diedrichs roasters hot rodded by people who have gone beyond that. Since this seems a very doable project, Diedrichs aren't the dead end roasters that many other "set it and forget it" models are.

Owner comments were in line with yours -- "love the roaster; the SOP, not so much"

Most of the hacks seemed to be about removing or diminishing some of the ceramic shielding that comes in the larger models. I've also seen a 5 pounder with a higher powered fan to allow more airflow.

The changes were usually done to make the roasters more nimble in changing temperature. It seems the Diedrichs SOP is for roasts in the 15 to 20 minute range, and the more experienced people were tweaking the roasters to make 10 to 15 minute roasts easier.

You might need to join the roasters' guild BBS to get the nuts and bolts; of which I have no clue.