Heat and Air

[ronnyg]

Ok everyone I am hoping to gather some thoughts, experience and expertise as I am not able to control things the way I am hoping to.  Here is the issue, I am struggling to maintain a slow and steadily declining RoR.  The best I have managed to do has been when I constantly adjust heat and air in reaction to the RoR and I mean constantly.  I want to know (if it is possible) what you all are doing to not have so many changes in heat and air (heat especially).  It would be nice to find a method that involves as few changes as possible in these variables around specific times in the roast to increase my chances of being able to repeat a similar profile for a similar result.  I usually roast around 415g and have the stock IR burner Mr. Li sent with a variac on the fan.  I am getting good roasts (although I know they could be much better) but I hate that I am constantly having to tweak variables.  I usually leave my air very low in the beginning than increase it near FC so the smoke and Chaffe don't really have a chance to build up at all inside the drum, so my biggest issue is in the constant heat adjustments.  Thanks for any help.

Ron

[hankua]

My opinion is its easier to use a pre-determined charge temp/weight and turning point. For example: I reduce the heat at the roast end to 50mmaq and leave it set for the next batch. When BT hits 180c/356f I drop in a fresh lb and reduce air to low. After 1:30 BT should be 80-90c/176-194f or should I say this is the general target turning temp.

By starting at a lower turning temp. without ET dropping too low, it allows more room for heat adjustment/ reduction. Huky can easily roast too fast, and should be adjusted by operator. I can turn the gas up to 4kpa and slowly reduce it or step it down to 1kpa and 50mmaq at the end.

The IR burner works differently than an open flame I think, Johnny had both and can comment on that. It's easier to add heat than get too hot and panic; my reasoning for stepping down the heat. It also allows the BT and ET reading to converge, slowing the roaster down where there is more control during the roast development stage.

If I was charging 1/2lb 150c/302f would probably work with corresponding less heat input along the way.

[edtbjon]

After playing around with different parameters, I have always had KFirs (at HB) basic reciepe as a basis for my roasts. Even though he now prefer the perforated drum, he has extensive experience with different setups on the Huky. Anyhow, he suggests much higher charge temps. (Like 225C for 300g and 280C for 450g/1#.)
But I will definitely try charging at lower temps, as a common denominator for me so far is that the roasts are very fast and I always have to hold back to get at 1Cs at say 9 min. It can easily race away and start at 7 min.
As usual, I take it common sense should be used and ample time should be spent warming up the machine. (Especially important for consistency, between roasting sessions and also between roasts in the same session.)

[Gregr]

I think you're right to look for a way to make fewer adjustments. If you stick with a strategy that has a smaller number of changes (and you log the adjustments) you'll be able to see the how big or small the effect of each change was pretty quick. The path I chose was an amalgamation of what I learned with the Behmor and Hottop. Randy Glass wrote a great tutorial for a basic roasting profile on the Hottop and that was the basis for how I roast with the Huky, adjusted for my taste preferences, bean types and of course for the differences in how the two machines work.
So here's the bottom line: my basic roasting strategy generally yields good and sometimes great espresso but I have lots more to learn. A Boot roasting class is in my future   
For the stove there's an adjustment during the ramp, one before first crack, a very small one when first crack starts, one when first crack is done and then possibly one more during development.
For the fan there's one when the beans are dry, when first crack is over and maybe one more during development- that's it.
Caveat: I'm using a solid drum so if you're using a perforated drum the numbers will be different. There's a thread in the Resources area (Huky threads at HB) covering this subject.
Stove setting- 2.5kPa for hard/high grown beans, a bit lower for softer beans and leave it there til the BT is 325F/163C. Then I raise it to 3.25kPa until 365F/185C, then I lower it to about .75/1.0kPa. First crack comes a minute later pretty consistently, then the stove goes to very very low- .25kPa. and often it stays there for the rest of the roast, but if I want more than 3 minutes of development I'll adjust based on the RoR.
The fan stays at 20-25% during warm up right til about 290F/143C (dry point). Then a brief burst at 50%, about 25 seconds, then back to 20% all the way til the end of first crack- then 50% til drop (adjusted possibly for longer development).
That little recipe yielded a lot of decent roasts during the time it took me to become familiar with how the roaster reacts to fan and heat adjustments. The beauty of this approach, or any approach you use consistently, is how easy it is to adjust when you come across a bean that you want to roast faster or slower, more or less development, faster or shorter ramp, etc.