According to RoastMaster, I've got 40 SR500 roasts under my belt as of today. I'm pretty happy with the technique I've developed so I thought I'd share it.
I'm not having as much of a problem with charring as I did the first few roasts, btw. I wonder if it runs hotter when it is new than it does after it's broken in a bit?
The main thing I've learned is that there isn't a simple time based formula I can use. Every bean and even every roast is a little different. Maybe this is obvious to others, but most of the roasters for sale seem to have an automatic mode or time based instructions or something else that implies you can get consistent results from consistent behavior. I've only found that to be true in a very broad sense.
So.. That said, here's my roasting technique:
I roast 4 ounce batches and start on low heat with high fan. I watch the beans very closely at first to get a sense for how well they'll move. Most of the time I just watch, but in some cases if the beans are not moving at all I'll use the tipping technique (about 30 degrees alternating front and both sides) for about a minute to get them dried out and moving a bit. I'll tip maybe 1 in 4 roasts.
I let it sit at low heat until the beans have reached a consistent brown (the stage before first crack in the SM color chart).
While waiting for a consistent color, I watch the movement of the beans. I want to keep them moving, but not too aggressively. As a rule of thumb, I keep an eye on a bean when it appears on top and do a slow count as it shifts down the side of the glass until it disappears behind the metal band. I try to keep it around 5. Usually this means I gradually drop the fan from full to about the 2/3 speed mark. Sometimes more, sometimes less. I don't think I've ever dropped below the half speed mark.
Reaching the desired consistency of color can take anywhere from 3-5 minutes. When I get there, I flip the heat off, then back on to medium which resets the timer to 5.9 and is a lot quicker than messing with the + + 6sec button.
First crack usually starts within 30 seconds of bumping the heat to medium. I continue to watch the speed and modify the fan as necessary during first crack.
If I am aiming for City, I wait until it's been about 20 seconds since I heard the last crack and then hit cool and bump the fan back to high.
If City+, I wait 60-90 seconds after the final crack depending on how consistent the color is.
For Full City, at 90 seconds, I bump the heat to high and listen carefully. As soon as I hear the first snap of 2nd crack I hit cool and bump the fan to high. This is usually within 30 seconds of bumping the heat.
For Full City+, I start timing when I hear 2 snaps in succession and hit cool and bump the fan after 20 seconds.
Hopefully this will be useful to someone.
Edit: added the batch size to above.
Bob
