BradS wrote:The shallower decreasing slope at the end of the roast was where I turned off the heat and left the fan running with the variac back at full (130VAC) to see if cooling could be done in situ with any degree of success. You can see - I got impatient and opened the roaster and dumped the beans! There is some more information on the roasting label below, mainly that I decreased the voltage from 110V to 105V to slow down the roast from 1st to 2nd... with fairly good results. I also seem to have a higher-than-normal offset on my temp reading as my temps seem about 40 degrees high compared to visual/audible cues.

I think that, based on the taste of this roast (much less sharp with more body and, well, taste) that I'm on the right track, but It's always nice to have an honest critique. I'd also like to ask other SC/TO users what their best success is with roasting repeatably. I think the variac will help me immensely, as I roast either on the back patio whenever possible or in the garage when necessary due to weather. I get much faster roasts in the garage for whatever reason, maybe either line voltage or ambient conditions, I don't know yet as I haven't used the variac in both places.

In any case, thanks again for all the information you share here.

Cheers,

Brad

Hi, Brad- I've been using an sc/to for almost a year now (I think..), but have never used it without the variac. Unless you've split-wired your turbo-oven (so you can run the fan independently of the heating element) adjusting the variac also adjusts the fan speed. I've tried that early on once I've hit my warm up temp, but found it easier to just leave it turned up full (130 v, in my case) and leave it alone. The biggest trouble I have with consistency has boiled down to two main issues: accurately measuring bean mass temp and achieving good agitation of the beans. My k-type TC and thermometer (the common one people buy from sweetmarias) fluctuates quite drastically when you near 1st crack (upper 300's) and really crazily over 400 (by as much as 25 or 30 deg). Most fluctuation is in the 10 degree range, which is pretty easy to average in your head as you're roasting- but it occasionally dips (not rises) down by as much as 30. I just chalk it up to the nature of that technology (those TC's are not exactly NIST certified). My roasts turn out fine, but my experience with this setup I've likened to pulling shots on a Europiccola (most of the time it's ok, sometimes not so ok, sometimes really great- depending on the bean). I think I can do better, but rather than modding my existing setup, I decided to just buy a decent drum roaster that'll do a good job with up to 1 lb of green.

One other tip I'd offer- maybe roast more than 1/2 lb at a time. I usual roast at least 300 gm, but found it a little easier with 350 in terms of getting an even roast.

Ray

Rainman wrote: My k-type TC and thermometer (the common one people buy from sweetmarias) fluctuates quite drastically when you near 1st crack (upper 300's) and really crazily over 400 (by as much as 25 or 30 deg). Most fluctuation is in the 10 degree range, which is pretty easy to average in your head as you're roasting- but it occasionally dips (not rises) down by as much as 30. I just chalk it up to the nature of that technology (those TC's are not exactly NIST certified).

Ray

I don't know about those particular TCs you reference, however even the cheap ones are fairly accurate in my experience. The probe I mounted permanently in my sample roaster was custom made for me by Omega, and I'm sure it is of very good quality and especially with the Fluke digital thermometer/datalogger I have it attached to, gives highly accurate and repeatable results. By the way, Omega is a great company to work with and they will talk with you on the phone to help you design a custom probe which they will then fabricate for you in less than 2 weeks. If my memory is correct, I paid about $60, 2 years ago, for this probe which is ensheathed in stainless steel and has heat insulation and is flexible at the far end.

Nonetheless, even a cheap digital thermometer that costs <$20, including the TC, will be accurate in my experience. The differences I've measured with a cheap TC on a cheap digital thermometer, vs. an expensive TC attached to my Fluke, are on the order of 1-2 degrees, and neither the cheap nor the expensive TC fluctuate much, they just read differently.

I have one of those IR TC things that looks like a pistol, that you can use to sample temperatures. In my experience, using it for roasting and getting temps from inside my roasting drum, you can get almost any temperature you want depending on where you aim the thing. I would not be able to depend on such a device for roasting coffee; it would give me very little additional information than simply looking at the beans as they roast.

ken

Abdon wrote:I think (therefore I could be horribly wrong) that messing with the temperature before a good roaring 1st crack is dicey at best.

I agree but I also agree with Ken with regards to the kind of roaster/roasting method you're using. They're all different and I would imagine even between the same electric home roasters they vary with regards to one's line voltage, ambient temperature and even altitude above sea level.

I find anticipating my Hottop is a bit like trying to turn a big rig...you've got to set up in advance. If I keep the heat high during 1st crack and only ease off 1/2 way or more into it the chamber temp responds very slowly and I'll go from 1st crack temp to 2nd crack very quickly, leaving me with a pretty short rest. Atleast for my Hottop it looks like backing off on the heat at the start of 1st crack would probably level off the temp towards the end where I'll have more of a chance to control the rest into 2nd.

Aside from the direct drum heat the Hottop has a programmable fan to allow for convection control as well. What's the benefit of the fan/convectional heat and at what stage is it best used for the roast? Setting up for first, through first or throughout the roast?

Ken Fox wrote:I don't know about those particular TCs you reference, however even the cheap ones are fairly accurate in my experience. The probe I mounted permanently in my sample roaster was custom made for me by Omega, and I'm sure it is of very good quality and especially with the Fluke digital thermometer/datalogger I have it attached to, gives highly accurate and repeatable results. By the way, Omega is a great company to work with and they will talk with you on the phone to help you design a custom probe which they will then fabricate for you in less than 2 weeks. If my memory is correct, I paid about $60, 2 years ago, for this probe which is ensheathed in stainless steel and has heat insulation and is flexible at the far end.

Nonetheless, even a cheap digital thermometer that costs <$20, including the TC, will be accurate in my experience. The differences I've measured with a cheap TC on a cheap digital thermometer, vs. an expensive TC attached to my Fluke, are on the order of 1-2 degrees, and neither the cheap nor the expensive TC fluctuate much, they just read differently.

I have one of those IR TC things that looks like a pistol, that you can use to sample temperatures. In my experience, using it for roasting and getting temps from inside my roasting drum, you can get almost any temperature you want depending on where you aim the thing. I would not be able to depend on such a device for roasting coffee; it would give me very little additional information than simply looking at the beans as they roast.

ken

It's possible that the placement could be the issue. The tip is protruding out from the bottom near the center, and some of the cloth sheathe may be stripped back far enough below the pan to affect it's reading somewhat. The readings are very stable up to around 350 deg F, then as they climb toward the upper 300's, start to fluctuate more (realizing fluctuation of readings and accuracy are different issues, of course). I could have sworn that somewhere (maybe over on the greencoffeebuyingclub forum from someone like Greg Anderson (aka "buttwhiskers") mentioned the accuracy of these units varying substantially at higher temps... yes/no? You sure, Ken? Either way, I'll have a chance to compare it w/ the TC that comes w/ my new roaster if I can figure out a way to match it's placement w/ the cheaper probe.

Ray

Ken,
It seems to me you are advocating an 8 minute 1st crack with another 4 minutes from that point until the roast is finished. That is a total of 12 minutes roasting time which in my opinion is to quick for almost any coffee except maybe shb fully washed and fermented.

My preferred roast usually end up at an 11 minute fist crack dropping the gas to low 30 seconds before first crack. With a total time with the gas on low of 2 minutes and 30 seconds. Then slowly bumping the gas up every 30 seconds until it is medium high finishing the roast at 16 minutes. That leaves a total time of 5 minutes in between the the start of first crack to the finish of the roast right before second crack for me as well.

This seems to work fine.
I have known several professional roasters who even prefer there first crack at 12 minutes start and 5 minutes from the beginning of first crack. That would make the total roast time about 17 minutes.

Slower profiles work better for dry processed coffees as there moisture content is all ready low and easy to scorch.

I prefer to drop by gas to low 30 seconds before 1st crack right before the beans to exothermic so bean temperature keeps going up on its on with minimal gas and the roast does not get out of control.

My question for you Ken is have you tried expanding the gap between 1st crack and the finish of your roast to five minutes and compared it to a roast finishing at the same time where the gap between 1st and second is only 4 minutes.

I would be curious to know your opinion of those coffees.
I realize that gap between the start of 1st crack and the finish of the roast is the most crucial to the whole roasting process. To long a stretch brings baked results to short brings coffees that have flavors that are undeveloped that may be bright and thin and missing body.

I have good results they way I roast coffee. But i did the experiment you suggested my 1st crack at 830 the finish of my roast at 1230 the coffee came out a little darker than it usually is for me.

I am going to cup the coffee a dry processed brazil and let you know what I think.

Thanks,
Anyone else with some opinions feel free to chime in.
This in itself to me is a great topic.

jason_casale wrote:Ken,
It seems to me you are advocating an 8 minute 1st crack with another 4 minutes from that point until the roast is finished. That is a total of 12 minutes roasting time which in my opinion is to quick for almost any coffee except maybe shb fully washed and fermented.

My question for you Ken is have you tried expanding the gap between 1st crack and the finish of your roast to five minutes and compared it to a roast finishing at the same time where the gap between 1st and second is only 4 minutes.

I would be curious to know your opinion of those coffees.
I realize that gap between the start of 1st crack and the finish of the roast is the most crucial to the whole roasting process. To long a stretch brings baked results to short brings coffees that have flavors that are undeveloped that may be bright and thin and missing body.

I have good results they way I roast coffee. But i did the experiment you suggested my 1st crack at 830 the finish of my roast at 1230 the coffee came out a little darker than it usually is for me.

I am going to cup the coffee a dry processed brazil and let you know what I think.

Thanks,
Anyone else with some opinions feel free to chime in.
This in itself to me is a great topic.

Hi Jason,

Actually, I did not recommend any particular profile to other users, especially people with different equipment than mine. At the end of my first post I did state what I have found, at this point, to work the best with my equipment, but it was intended simply to illustrate an approach that had developed on the basis of my own study of the results in my own roaster, over a period of years. Here is what I stated at the start of the post, which was the "meat" of what I was trying to get across:

Ken Fox wrote:Here is a description of the roasting parameters that work best in my equipment and may or may not work well in yours. Even if my parameters don't work for you, knowing that these parameters exist may help you to experiment a bit with altering them in order to find what works best for you. I have a drum and therefore if you air roast you will need to extrapolate to your particular set up, as the processes are different even if the results can be similar.

In answer to your question, there was a period of time during which I did not even have a strong enough heat source to roast as quickly as I now roast, whatever I might have wanted to do. After I changed the heat source (the burner) to something more powerful, and later adjusted to a change of fuel from propane to natural gas, I still roasted much longer profiles than I now use, averaging about 16 minutes (sometimes 18 minutes) in total to a bit darker roast level, although the difference in roast level isn't anything approaching the ~4 minute difference in roast times. I used to routinely hit first crack after 10 or even 11 minutes, and had years when I roasted like this.

My experience with my particular roaster, which is probably not similar to most peoples' roasters, was that roasts that took 10 or 11 minutes to hit first crack invariably tasted "flat" or "dull." I had several people whose tastes I respect tell me that when I sent them samples of my roasts, and it was suggested to me by more than one of these people to speed up the time to the onset of 1st.

Each roaster has its own best profiles, which are probably going to differ a bit by bean but the overall average profile for any given roaster is probably going to be fairly similar, at least in my experience.

As to extending the time from onset 1st to the termination of the roast, I think this is going to depend in part on how dark you are roasting. I am able to reliably get 4 minutes in between the onset of 1st and where I terminate the roast, typically several degrees before the onset of 2nd. Could I get 5 minutes in there? Maybe, but I think the risk of stalling out would be higher and I'd really have to stand in front of the roaster every second to try to avoid that. I might try it, but I'm not sure I really want to go in that direction as it would be a real PITA, especially if I stall out and then have to dispose of the coffee on some unsuspecting friend

ken

Ken,
Thanks for the reply.
As we have been peers and colleague's in espresso since alt.coffee.
I figured I could ask candid questions without taking them the wrong way.
I myself am never locked into a formula for anything so I wanted to try your methodology to see if it gave me better results with my own roaster.

As to getting 5 minutes in between 1st crack to the finish.
I start my timing cycle when I drop the temp 30 seconds before 1st crack and include that with my timing that is how I am getting 2 minutes and 30 seconds on low. Then I slowly increase the temp every 30 seconds until it is medium high.
By that point I usually have about 1 minute and 30 seconds to until the roast is finished. This is how I am able to achieve that 5 minute span with repeatable accuracy.

I am wondering what your current final finishing roast times are.
12to 13 minutes I am guessing.

As far as roasting we are not locked into a system we all have to find what works optimal for us.
Good for you for doing that.

I cupped my Brazil roasted in the profile you are using and it cam out less than optimal for me.
My roaster out a nutty brazil but finished roasty ashy and bitter a bit.

Oh well I will roast some brazil today at my optimal roast times and compare it to the brazil I roasted with your profile.

Learning is sure fun.

Best Regards

jason_casale wrote:Ken,

I myself am never locked into a formula for anything so I wanted to try your methodology to see if it gave me better results with my own roaster.

As to getting 5 minutes in between 1st crack to the finish.
I start my timing cycle when I drop the temp 30 seconds before 1st crack and include that with my timing that is how I am getting 2 minutes and 30 seconds on low. Then I slowly increase the temp every 30 seconds until it is medium high.
By that point I usually have about 1 minute and 30 seconds to until the roast is finished. This is how I am able to achieve that 5 minute span with repeatable accuracy.

I am wondering what your current final finishing roast times are.
12to 13 minutes I am guessing.

As far as roasting we are not locked into a system we all have to find what works optimal for us.
Good for you for doing that.
Learning is sure fun.

Best Regards

My typical roast times these days are around 12 minutes.

I don't think that a profile that works with a certain roaster will necessarily work with others; you have to play around with them. And it is completely possible that two years from now we will both be roasting differently. The key is to taste what you have roasted and to make changes as needed. I just roasted a new Kenyan a few days ago and so far I don't like it very much the way I roasted it, however I did have some problems keeping the temperature from stalling after the onset of 1st crack, so perhaps I just need to give those beans more heat the next time around.

My current finishing roast temps are about 435F, making allowances for the fact that my TC probe reads hotter than reality.

Take care and good luck!

ken

You know just doing some quick research in sample roasters.
It seems they cant line up with regular drum roasters profiles.
in other words they will not profile the same.
I saw some online saying they actually profile faster.
That would agree with your overall results.
I think both have had good experiences learning to roast on our equipment
over the past couple of years.

One thing is for sure you certainly learn the most about roasting using 100 percent manual equipment is a great teacher.
I have learned more about roasting than I would have using a computer aided roaster.
The down side you have to constantly monitor your roast and you are always making changes as you move along.

Gas fired roasting is a beautiful thing we have so much more control over the roast than when we home roasted.
Now having that experience I am not sure I could ever go back to a home roaster.

No offense to home roasters as you people get amazing results often times out of those little roasters.

I wish you the best out of your roasting.

jason_casale wrote:You know just doing some quick research in sample roasters.
It seems they cant line up with regular drum roasters profiles.
in other words they will not profile the same.
I saw some online saying they actually profile faster.
That would agree with your overall results.

One thing is for sure you certainly learn the most about roasting using 100 percent manual equipment is a great teacher.

The down side you have to constantly monitor your roast and you are always making changes as you move along.

Gas fired roasting is a beautiful thing we have so much more control over the roast than when we home roasted.
Now having that experience I am not sure I could ever go back to a home roaster.

I wouldn't admit this if I didn't know that you could keep a secret

There was a time when I used to approach home roasting as a chore, and would find other things to do when I roasted, such things as waxing my skis across from the roaster, in the garage.

That definitely impacted my results, and not for the better!

ken