SR500 owners - get in here!

[Barrie]

I am no expert, having only a couple of months' experience - about 34 roasts so far, so I am very much a learner.
I have come to believe that the scorched beans are most likely to be those sitting on the metal ledge at the top of the (sides of the) perforated metal base of the bean container. You can see stationary beans at the bottom of the glass sides in the first minute or two, and it is unlikely that the beans at the bottom (on the perforations) would not move, as they are the ones most exposed to the air flow.
I am not keen on using a bean-mixing method that involves taking off the chaff collector and so I use tilting to dislodge the beans at the sides. Always roasting 113g at a time, at one minute I take a large pot holder to keep the chaff collector in place while I tilt the whole thing sideways to about 45 degrees. I do this in the N,S,E, and W directions. stopping each time once the air flow dislodges the beans at the sides.
I have not had any problem with uneven roasting with SO beans, although blended beans vary in the speed at which they become brown during the roasting process. This was particularly the case this morning when I roasted some SM Liquid Amber Blend. I certainly have not experienced individual burned beans. Possibly out of naivete, I think I have that issue in hand.
That said, I am struggling with identifying exactly when to stop a roast in order to arrive at a specific target - I drink only espresso, and so tend to aim for FC+, Vienna, or French Roast, depending on the bean, always going to SM's stated upper limit. I keep records and use a thermometer, the calibration of which is off - 4% low in boiling water. I do not think that matters as long as I am aware of it. Reproducibility is probably more important than the exact number. In my mind, I add 15 to the measured temperature in the target range. I need to play more with the controls. At the moment I use 100% fan/low heat for the first three minutes, until the beans are amber. I understand this helps provide more even drying within the beans, then I go to 50% fan/high heat the rest of the way. I see that some roasters slow the process again after first crack, to identify 2C and its stages more easily. I need to do more roasts to be sure that I can get reproducible results with the beans that I like, then I will try fiddling with the controls a bit more. Great fun?

[arjaybee]

I keep records and use a thermometer, the calibration of which is off - 4% low in boiling water. I do not think that matters as long as I am aware of it.

I picked up the $30 thermometer with K-Type thermocouple that SM sells. Is that what you use, or something similar? I've only used it a couple times and haven't really kept records yet. I just snaked the thermocouple wire past the screen and through the center of the chaff collector. I bent the wire until it's away from the glass and more or less in the midst of the bean mass. I'd like to come up with something better, but this seems to work OK.

[Barrie]

I keep records and use a thermometer, the calibration of which is off - 4% low in boiling water. I do not think that matters as long as I am aware of it.

I picked up the $30 thermometer with K-Type thermocouple that SM sells. Is that what you use, or something similar? I've only used it a couple times and haven't really kept records yet. I just snaked the thermocouple wire past the screen and through the center of the chaff collector. I bent the wire until it's away from the glass and more or less in the midst of the bean mass. I'd like to come up with something better, but this seems to work OK.

Yes, I use a K-type thermocouple and digital thermometer but I bought them elsewhere. You may be interested in a thread on the subject that I started in the Air Roaster section: "How to measure temperature in an SR 500?" I followed the idea of a home-brew wire guide for the thermocouple.
Knowing the temperature is certainly not the be-all and end-all of roasting but, rather, one component that can be a help. For example, it has bailed me out when I have made a stupid mistake like forgetting to restart the timer and letting the beast go into Cooling, unnoticed, before I was ready. I spotted it quite quickly as the temperatures went down.
I am finding from my records that events such as first crack, for example, occur in much the same temperature range every time and so this is just another guide as to the stage you have reached. I suppose I use it as confirmation, but certainly would not like to have my actions determined entirely by the temperature alone. As another example, when the ambient temperature is different from what you are accustomed to, the thermometer helps when the time to each stage seems longer or shorter (I roast in the kitchen with exhaust fan on, indoor door shut, and outside door open).

[bigbells]

Always roasting 113g at a time, at one minute I take a large pot holder to keep the chaff collector in place while I tilt the whole thing sideways to about 45 degrees. I do this in the N,S,E, and W directions. stopping each time once the air flow dislodges the beans at the sides.

I set out to prove that I can get a completely even roast in my SR 500 without any tilting, stirring etc. OK, so it's an obsession of mine to prove to Barrie that it can be done. This is a 7.5 minute roast of Columbia Dos Payasos de Tolima. Amount: 130 grams. Fan: 100% for the first 4 minutes, 55% thereafter. Heat: Low for first 3 minutes, medium for 4th minute, high for 5th minute, back to medium for remainder of time. The roast is very, very even, even more so than the picture indicates. Every bean looks very much the same.

[Barrie]

I have just been re-reading Marías comments (on their website) about choosing a roaster and was struck by this paragraph.

Another point: we get people who say, "I love ______ (Peet's, Starbucks, etc.) coffee - how do I get that flavor with home roasting?" I say, "Go to the store and buy ______ (Peet's, Starbucks, etc.)." Really ... home roasting is essentially an "adventure in flavors" in which you find the coffees, the degree of roast, and the technique you like. If that already exists in ______ (Peet's, Starbucks, etc.), then why home roast? If you are not happy with what you can find, or want a bit more variety - that is a great reason to home roast.

I was one of those people when I started roasting with an SR 500 a couple of months ago. My objective was to reproduce something like Peet's French Roast. I am an espresso drinker and, up to that time, I had mainly been drinking americanos but have now gone back to straight shots, and am very much appreciating my expanded insight into what I am drinking. Peet's FR is no longer my objective. I have enjoyed a number of coffees in the FC to Vienna range, and look forward to improving my repertoire. I wonder how many others have gone through this same "turning on of the lights"?
Bigbells, you could make a believer of me yet - the lights are still on, but for the meantime I will continue tilting as the results are as good as yours.

[arjaybee]

I set out to prove that I can get a completely even roast in my SR 500 without any tilting, stirring etc. OK, so it's an obsession of mine to prove to Barrie that it can be done. This is a 7.5 minute roast of Columbia Dos Payasos de Tolima. Amount: 130 grams. Fan: 100% for the first 4 minutes, 55% thereafter. Heat: Low for first 3 minutes, medium for 4th minute, high for 5th minute, back to medium for remainder of time. The roast is very, very even, even more so than the picture indicates. Every bean looks very much the same.

Even with fan on high, heat on low, I can see beans starting to scorch in the first minute. I wonder what the difference is?

[bigbells]

Even with fan on high, heat on low, I can see beans starting to scorch in the first minute. I wonder what the difference is?

I'm taking shots in the dark here: are you weighing the beans you put in? For some beans, loading up to the bottom of the metal band would be well over 4.5 oz: too much.
Is there any chance that you've had some chaff get into the vents in the bottom of the roaster?
If neither of the above, then I'd have to say you're either getting too much heat on low setting, or not enough fan at the highest setting, or both. Maximum fan always keeps the beans moving enough to prevent scorching on my unit, and as the beans expand and attain lower density, they keep moving at lower fan settings.

[arjaybee]

are you weighing the beans you put in?

Yes, I'm weighing out 4 oz.

[WVEd]

Attached is my 7th roast. I seem to have somewhat settled into going for a Full City+. I too have seen 2-3 rogue extra dark beans early in the roast but I also want to avoid stirring/tilting etc. I think I am getting satisfactory results at medium heat, starting at full fan and 6.9 minutes. I drop the fan to about 85% at 5.9, about 65% at 4.9 and to 50% at 3.9 until cool at which time I go back to full fan for cooling. I am also well into the second crack but the beans don't seem to look that dark. Please feel free to judge my roast grading/quality to help me establish some benchmarks. Every pot has been great so far compared to the swill in the past.... Thanks for the critique and comments in advance. Regards, Ed

small Full City+.JPG (65.23 KiB) Viewed 336 times

[bigbells]

Looking good, Ed! If you wanted to avoid the occasional rogue bean, I'd try leaving the fan on full power for the first 3 minutes. Then again, the amount of variation I see in your picture wouldn't bother me.