1# FC in 17 minutes easing through 1st with good steady 1st and good pause before 2nd. Ready for roasting for comparisons prime time.

Randy G wrote:As an example, everything I have learned about roasting (as comparatively little that may or may not be) states that the bean temperature should never be allowed to drop during the roasting cycle. Holding it steady is OK. The graphs show about a 30 degree drop in temperature

Carl Staub, of Agtron fame, says dropping environmental temperatures detracts from the roast quality. On the other hand, there's a few commercial drum roasters that blw cold air into the drum to hold beans to a preprogrammed profile. I make sure I never program a bean temperature profile into my P1 that drops the temperature of the air blowing in (basically, no sharp corners in the profile). My cupping on this has been unscientific, and I'm not aware of any tests that back up Staub's ideas.

Randy G. wrote:As an example, everything I have learned about roasting (as comparatively little that may or may not be) states that the bean temperature should never be allowed to drop during the roasting cycle. Holding it steady is OK. The graphs show about a 30 degree drop in temperature which, on its own, would indicate a poor appliance, but as I indicated above, since we do not know the temperature inside the drum nor the beans' temperature the data being presented is not all that useful when speaking of the roast itself. At least to say that it makes it very difficult, if not impossible, to compare the roasts of the Behmor appliance to most any other roaster.

As previously noted the graph is indeed roast environment. I dropped the environment temperature heading into 1st, doesn't mean the bean temperature dropped. Note the environmental temperature was always well above the 1st crack bean temperature range, dropping from a peak on the pre-1st push of 502f! That 30 degree environmental drop going into first had virtually nothing to do with appliance design and was totally planned and intentional. Manual variable boosted heater controlled roast. And since 1st cracked was steady and sustained and following pause proceeded to 2nd without increased heat obviously the roast chamber was not too cool to finish the roast to intended Full City. Actually the last stage 96v to heater stabilized at ~463f so would have easily gone to hard rolling 2nd. In fact I'd intially planned the roast profile to increase heater voltage up at the 16 minute mark but during roast deemed it unnecessary. Reducing applied heat going into first is not uncommon in drum roasting. Commercial drum roasting usual done combination of lower flame and increased air flow.

Another observation is the overly-long cooling period. According to the last graph, at the end of the roast when cooling started it took about 4 minutes to go from about 470 to 280 degrees. Again, this is only the chamber temperature, but points towards the need to get the drum out and cool the beans externally for the best possible results.

Indeed it took 5.5 minutes from end of roast to get to 200f range, which I deem critical cooling point. However, until comparisons of in roaster cooling done with yanking the drum for faster cooling it's premature to assume in roaster cooling will yield inferior rather than equal or even superior cup.

Randy G. wrote:"The graphs show about a 30 degree drop in temperature which, on its own, would indicate a poor appliance, but as I indicated above [referring to a statement in my original post], since we do not know the temperature inside the drum nor the beans' temperature the data being presented is not all that useful when speaking of the roast itself."

Ah see a problem. I need to post some photos! The drum is open mesh type. So yes the TC is outside the drum ~3/4 inch away from the center of the left end, but since open mesh the temp while it may be different than insdie the drum it's highly doubtful to be much different.

We can guess and assume all we want, but with no data to back it up it is virtually impossible to know that the roasts are doing as well as they can, or even doing what we assume is being done, if there is no way to quantify it objectively. I would like to KNOW exactly how did dropping the temperature as you did in the chamber affected the temperature of the bean mass. Did the rate of increase hold steady? Did it lessen the rate of temperature rise 2 degrees/minute for two minutes? Did it drop? I don't know. I WOULD like to know.

When has it been said any Behmor roast that has been done is "doing as well as they can"? I don't have a clue what you mean by "or even doing what we assume is being done". The beans tan, they brown, they proceed to 1st and 2nd crack at given times and temps. No assumptions about that. The roast in question had a sustained moderate paced 1st crack of ~3:30 duration with ~2 minute pause before 2nd, again no assumption on what the bean is doing. That roast happened to do fairly closely what I intended it to do. As far as knowing how dropping the temp affected the bean mass, first I'll say the environament temp was peak 502f when lowering heater power and the beans had not started 1st crack therefore the beans were much cooler than roasting environment since if the beans were actually 502f they would have been past Spanish Roast and in flames. I'll know how using that type of profile with the Behmor affects the beans when I get to the roast comparison in the cup stage of testing and a similar profile but not taking roast environment as hot before the ease into 1st. I do already know that with 1# batch lower environment temp early results in anemic 1st. Burning through test beans to learn the Behmor bean behavior as stated earlier. Measuring bean temps is over rated IMO. (And I've been doing it regulary for going on 6 years around a thousand roasts.) More important to gain an understanding of what's the beans telling you with your senses. In a recent SM List discussion Tom said in part

...consistency and roast quality are more important than whether or not you are measuring the bean temp. Have you ever used a Probat? It's something 90% of commercial coffee roasters deal with - you are usually not measuring bean temp...

miKe mcKoffee wrote:I knew somebody was going to ask for graphs! "Only takes a moment" to create graphs in Excel assumes a couple things: 1) have Excel and 2) already know how to quickly create charts in Excel. Ok for 1) I do have full Office Suite. However for 2) I am not proficient with Excel and spent over a half hour messing with a line chart and how the hell do you change the axis so each 30 second temp data point entered is 30 seconds (or 0.5 minutes) instead of 1 minute increment. I'm not wasting any more time on it, don't have the time to waste!

Anyone is more than welcome to convert my data to graphical! I have more test data to key in and post and many many more test roasts to do rather than learning Excel graphing...

Right Click and Save Target As... this Roast Log Plotter. Also does Shots PM if you need help formatting your data

Sorry for no posts or updates, my focus is back where it belongs and must remain, getting mcKona Koffee Roastery Kafe off the ground.

Chris's 1st look with some good pictures http://ineedcoffee.com/07/behmor1600/

another_jim wrote:Carl Staub, of Agtron fame, says dropping environmental temperatures detracts from the roast quality.

Even if that's an accurate quote (I don't remember where I read it but I remember his having said you didn't want the environment temperature dropping below the bean temperature), he's assuming that convective transfer is the dominant path of heat into the beans. That's true for both air roasters and commercial drum roasters, but doesn't seem to be the case with the Hottop and I would guess even less with the Behmor. I say this because on the computer-controlled Hottop, I will stall first, when the beans are highly endothermic, if the environment temperature is quite high but the element is off, whereas I won't stall it if the environment temperature is much lower but the element is on. From that I conclude that radiative transfer is much more of a factor in a roaster with a perforated drum and a heating element putting out a lot of infrared. In the Behmor, where the drum is wire and much less opaque, and the element is a quartz one instead of a Calrod, I'd be surprised if the dropping environment temperature meant a dropping bean temperature.

Best,
David

Haven't had/made/found time to do any more testroasting of stock profile configurations. However, I have been using the Behmor as my production roaster with excellent results in the cup. Enough so I'm confident enough in the results to roast any bean. Today's first cup of the morning Cafe Crema Americano of Panama Gesha Esmerelda was on par (or better) than any Rosto profiled roast done in the past. This cup is actually the tale end of this 1# Gesha batch roasted 7/30 with half of the batch vac' sealed and frozen immediately post cooling, removed from freezer a week ago 8/4. This is not this year's new crop Gesha but from the none COE lot SM got in latter part of '06, greens kept vac' sealed room temp. The Gesha 1# roast was a 18:30 total roast time to Light Full City. Superb balance of the wonderful Gesha acidity with very good body. Tuesday of this week roasted 1# batchs of CR Las Laja WP & Miel go LFC in 16:30 with slighly different profile than used for the Gesha. Actually used lower initial heat for the faster roast but held the boost longer. (126v vs. 132v). Haven't had a dud roast yet. Kenyas, Yirgs, Konas, Sumatras etc. all good. I am not using closed door cooling but also not removing drum for speed cooling. Opening the door at start of cooling cycle seems to work quite well 1# batch. Though the Sulawesi 1# roast I did previously with full closed door cooling did turn out excellent (stock P1 18min), haven't tried full closed door cooling with a "bright" coffee.

I have not been using stock configuration however. Stock I'd likely only use the P1 or maybe for some P2 profiles for full pound batches. The other profiles just seem to start too low heat for full pounds.

I didn't like the draw fan/after burner not coming on until 7:30 into the roast when using 1# settings with manual heater control so have gone to using 1/2# setting P5 time maxed to 17:30 for my 1# batches with manual heater control. (The longest possible time with 1/2# selected.) This yields the fan/AB coming on 5 minutes into the roast. I did this not for the after burner but for adding air flow earlier which I believe adds some convection and evenier early roast development. Alchemist has been playing with higher RPM drum motors (30 and has a 60 coming) which I believe is also aiding better convection and more robust 1st cracks and reduced roast times. The stock drum motor is around 12 to 15 rpm IIRC. I'll likely follow suite and add the motor mod'.

If I was just starting my home roasting journey would I be happy with the Behmor stock results? I believe the answer would be yes. As a bit more advanced home roaster accustomed to having good control of my roasts so far happy with the results in the cup and hackability of the Behmor.

Oh, thoughts on the wire mesh drum. It is a 5 count. (mesh of 5 openings per inch.) Works fine for most beans but some smaller will loose a few though very few. Believe 6 count might be ideal. But don't know how much smaller opening would impede chaff exiting the drum so that may have been the trade off. Speaking of chaff, does an ok job but also suspect higher rpm drum will have additional benefit of a bit better chaff removal.

This 2nd cup of the morning Kenya cap' I just made Debi & I is quite delish too. Bean resting and waking up quite nicely, much better than yesterday's shorter 3 day rest. (which is what I have found normal most beans most roasts) 1# 16min batch to barest early 2nd open door cooled.