Charge Temp

[wideasleep1]

About the drum speed, I'm not sure if the high 72rpm suggested and implemented by Slickrock is really needed. While I can understand his arguments, I decided to try a slower speed and I think it works.

What were his arguments? Also, 'needed' versus 'desireable' are not the same..I don't think rpm is 'need', versus what is 'best'..and that is subjective, so I await your cup results with interest.



 

Also, I don't think that there is that much difference in conduction if someone would compare a solid and perforated drum for that aspect.

Quite possible, but why would Mr. Li or 'common perception' then prefer a particular drum type/motor combo? With the reduced mass of the perf, the convection injects more influence in the roast (and presumably the cup), so is this compensatory to conduction/motor speed in your mind?


 

Now, what I've done is not to change the motor. The 72rpm is actually more silent to begin with. I simply use another transfomator (for an HP inkjet printer, which is at 18V instead of 24V, which gives me around 54 rpm to be precise. The benefit is a more silent solution. ("I just love the sound of first crack in the morning..." Sorry, I couldn't hold that one back... )
I also saw some posts on HB where one or a few users were at even lower speeds.

While Scott Rao's "commandments" really are recommendations, I find them very useful while I'm learning roasting coffee in general and the Huky in particular. The suggestion from Hank makes it much easier to manipulate the roast in whichever direction I want. If I'd want to roast for 15 minutes I can still maintain a declining RoR without flat-lining.

Now, the proof is in the cup and I have to wait a few days for that, but this and a couple of other roasts I made this afternoon looks really promising.

Thanks for sharing this, and looking forward to your cup results. Others seem to be dropping higher, but I wonder if they're 'third wave' lemon juicer roasters.

(edit: sorry if my questions don't seem coherent..a few glasses of wine, I'm just interested in the topic and want to explore this 'anomoly')... 

[edtbjon]

Being a bit more precise about sources, the article by SlickRock on HB is linked from our "Resources/HUKY Threads at HB" section. The part about "rpm" is in the review by SlickRock, part 2.
(You're correct about "needed" vs. "desired". That's what I meant, but it got lost in translation. My native tounge is Swedish.)

I just had a couple of cups this morning and they are the best roasts I've made with the Huky so far. They are only 48 hours old and already start to show both the balance and the complexity which I seek for.

To recapitualte (sp?) what did I change and what did I focus on?
First, I radically lowered the charge temperature from 230C to 150C. TP (at say 90-100C / about 200F) comes at roughly 1.30 to 2.00 minutes anyhow. But now I can be a bit more aggressive with the heat in the beginning. This also gives me more room to manouver through the rest of the roast without flat-lining the RoR (which would bake the roast).
Second, I recalibrated the fan system. Scott Rao recommends taking out the tryer spoon and using a ligher to find where the fan starts to create a negative pressure inside the drum. I set my zero for the fan dimmer/variac just shy of that point. Obviously the fan doesn't have any effect before that. (My "old zero point" was rather just seeing the fan slowly spinning.)
I was also much more aggressive with the air (compared to my previous roasts). Part of my reasoning for this was my experience with my old Gene Cafe roaster, from which I got some pretty decent roasts. That roaster only uses hot fanned air.

I've noticed that I do have to let the roasts mature much longer time with this roaster, but that is the subject of another thread... But I do expect these last roasts to be even better next week. 

[wideasleep1]

Brilliant! You're a rock star! This is exactly what I'm looking for. I need to focus and process this...

edit:

"Second, I recalibrated the fan system. Scott Rao recommends taking out the tryer spoon and using a ligher to find where the fan starts to create a negative pressure inside the drum. I set my zero for the fan dimmer/variac just shy of that point. Obviously the fan doesn't have any effect before that. (My "old zero point" was rather just seeing the fan slowly spinning.)"

This by itself sounds like a great suggestion towards 'the Huky owners guide to roasting'. an axiom, if you will.


edit: Ah yes...I'd read slickrocks thread, but that was back in early December when I was plotting Huky acquisition. That and I can't remember this morning, so December is right out. It would do me good to study.

Speaking of, appreciate Scott Rao's suggestions too...keep those coming (since I don't really want to read the book...unless there's a cliff notes version!) LOL! Declining RoR, and 'zero' your air is what I have so far.

[zivsade]

I've been using Kfir's recommended charge temps (220-230C (430F) for 300g)until today, when I radically lowered the charge temp to around 150C (300F) as recommended by Hankua. (Even though the example below has a charge temp of 178C (350F).)  That made a huge difference for me and it's much easier this way.
There are two benefits here (refering to Scott Rao's commandments). I can now add more (read "enough") energy at the start of the roast and second, it's easier to have a steadily declining RoR without stalling.

Now, I just have to wait a few days for the beans to mature...

About the Celcius/Farenheit issue... I always press the default button in the Phases dialogue. There I get the color fields at 150C/300F for drying point and another border at the typical 1Cs at about 200C/392F.

edtbjon - please note that while your BT was around 150C during the charge, your MET was @ ~230C during the charge & I think it had much more effect on the roast and the TP time & temp then the BT.

I would bet that if you will try the same BT charge temp but with similar MET temp as the BT, then you TP time will be longer and will have much lower temp.

It is interesting to try, because all of us are talking about the BT charge temp as a stand alone without referring to the MET and the ET, while I find that the MET has a large impact on the roast.

[edtbjon]

To me this is a matter of how to go about pre-heating the machine before the first roast and how to adjust/maintain the heat in-between roasts. (The "Harry Chang challenge" thread comes to mind.)
For me, getting to a steady temp (especially getting as low as 150C/300F) means using the fan and setting my IR-stove to the small flame setting (see pic.). Then it's a matter of some version of "the Huky dance", i.e. lift the exhaust pipe, insert the funnel and pour the greens, press "Charge" in Artisan and then replace the whole thing and get some fan going...
Personally, I would appreciate some input on how others have created a working procedure for the first and subsequent roasts.

[zivsade]

To me this is a matter of how to go about pre-heating the machine before the first roast and how to adjust/maintain the heat in-between roasts. (The "Harry Chang challenge" thread comes to mind.)
For me, getting to a steady temp (especially getting as low as 150C/300F) means using the fan and setting my IR-stove to the small flame setting (see pic.). Then it's a matter of some version of "the Huky dance", i.e. lift the exhaust pipe, insert the funnel and pour the greens, press "Charge" in Artisan and then replace the whole thing and get some fan going...
Personally, I would appreciate some input on how others have created a working procedure for the first and subsequent roasts.

Sorry edtbjon, but you missed my point -

It doesn't really matter what gas settings you are using. The thing that do matter is the temperature of the inside of the drum ET as well as BT - when there are no beans (before charge) and the temperature outside the drum - MET.

On the roast profile you uploaded the MET was ~ 230C and that is why also you charge the bean on low temperature of 150C your TP was after 1:30-1:45 and @ BT > 100.

My clame is that if you where charging @ the same BT temp with lower MET then the actual MET of 230, the your TP time would be much longer @ much lower temperature.

[edtbjon]

I got a bit frustrated when I was posting, as I tried to post a too large picture. I couldn't go back and post the already written text, which had then gone to the final resting place for old used bits and bytes... , but had to rewrite. My comment about TC's and the too high MET got lost there... Sorry.
I did look at the subsequent roasts I did that day and they all had about the same temp on all three TCs, so that particular problem wasn't there on subsequent roasts. (The posted one was the first roast of the session.)
My point about the gas setting is rather about knowing how to throttle the gas, which was the toughest part when trying to get the machine steady at 150C. If I use the IR stove on the 3 flames setting it will be too much heat to coast at one temp, or worse, try to reduce the heat, as I cannot go that low on the gas without the flame dying. Hence I posted what I learned from a post on HB.
I also like to point out that while writing these posts there are occational "aha's", i.e. I think I know what to do next time to remedy this or that...
Even gouvernors say... "I'll be back". 

[wideasleep1]

I also like to point out that while writing these posts there are occational "aha's", i.e. I think I know what to do next time to remedy this or that...
Even gouvernors say... "I'll be back". 

And that's the beauty of discussion! I love knowing *why* something was done the way it was done, rather than just 'I done this/that'. Keen on your findings.

[hankua]

Ziv is on to something. MET does matter, and if you do back to back roasts with the gas on low/air low after the drop; one can repeat a profile over and over. (Using the same charge temp. and dropping in quickly)

But I think it's better to focus on BT/ET delta because the probe placements are brilliant, with the ET in the drum center. Since the roaster has little mass, MET is the third parameter to keep an eye on. Or in my case, "flame out" indicator. 

It does get a little dicey trying to monitor so many different things, sometimes you just have to pick and choose; BT is first in line.

[zivsade]

Ziv is on to something. MET does matter, and if you do back to back roasts with the gas on low/air low after the drop; one can repeat a profile over and over. (Using the same charge temp. and dropping in quickly)

But I think it's better to focus on BT/ET delta because the probe placements are brilliant, with the ET in the drum center. Since the roaster has little mass, MET is the third parameter to keep an eye on. Or in my case, "flame out" indicator. 

It does get a little dicey trying to monitor so many different things, sometimes you just have to pick and choose; BT is first in line.

Hank - I'm looking @ MET & BT since my ET is analog and I prefer to work with the digital thermocouples.

The point I wanted to make is that whatever you choose to follow there is a big difference between charge BT temp of 150C/300F with MET of 240c to a same BT & MET charge temp of 150C. The latter will cause late and low TP.

Since we both using the solid drum currently- I find that MET is a good predictor, but
Then again - ET works fine as well.

[edtbjon]

I did some 5 roasts yesterday. I really wanted to try out having all the TC's (BT, ET and not least: MET) at about the same "low" temp of around 150C/300F. I tried that for a couple of 240g roasts and found that it was quite difficult to get a decent rise of BT for quite some time into the roast. ... and no, the TP wasn't late, but low as there wasn't much heat to make the temp turn back up. 
It seems like the roaster, i.e. "all" of the machine, was too cold, so I had to "waste" a lot of gas to reheat for the whole machine. I don't think that is good for the roast. It was hard to reach 150C again before 5 or even 6 minutes. (70-80%++ gas... and this with a small load of greens.)
I really do buy into Hanks proposed lower charge temp. There is a lot to benefit from that, like being able to add much energy to the beans in the beginning of the roast while still being able to have lots of latitude in terms of total roast time. In terms of DeltaBT, I have to lower the DeltaBT rather quick if I charge at a high temp and thus have a higher TP-temp. At a lower charge temp I can maintain the high DeltaBT a bit longer, without running the risk of flat-lining in the end.

Of course there should be some common sense in this. The machine (MET) shouldn't be cherry red, while the inside of the drum is cool from running the fan at full speed. But when there's a decent balance, like say: a steady BT/ET at 150C and steady MET at 230C, I can get a bit lower start from where both the then inherent heat of the machine and the heat from the gas flames can add energy to the beans in the beginning of the roast. In my mind it's just energy transfered to the beans. The difference would be that if the MET is very high, the drum will transfer more of the heat by direct contact (conduction) while if the MET is lower, a bit more heat is transfered in the heated air (convection). I take it the latter, i.e. convection, is preferable.

Back to yesterday, I got the last couple of roasts more where I wanted them. The BT/ET was around 160C while MET was around 220-230C.  (240g of greens...) I got from start to DE in about the same time as from DE to FCs, which was at 8.30. From there on it was a matter of adding enough air and lowering the heat so that I had a Full City instead of a oily Frenchie at around 11min. Artisan was playing up a bit, but at least it showed the temp values to the right. (Hence no presentable graphs...) These last roasts looks very promising though.

Again, I really enjoy these discussions. This is a small machine so I can roast quite often and try out new approaches and ideas derived from these topics.

[hankua]

Another factor to consider is ambient temp. in your roasting space. What about wind if your roasting outside or near a door?
Unless you have a temperature controlled environment, adjustments are made to compensate for cold weather.

Which brings me to the turning point temp. and the idea of keeping it in a range that fits your style of roasting. I shoot for @90*C/194*f.  This is the point in the roast where I think the machine, beans, and BT thermocouple have equalized temps.

But roasters that use bare end thermocouples have found the turning point is much sooner than 1:30 after charge. It doesn't really matter so long as the process repeats itself with the standard thermocouples we all have. In one sense the turning point is the beginning of the roasting process, where the beans can start accepting the heat your applying.

If I'm charging 454g at 180-200c/356f-392f, 226g, the 1/2lb charge gets reduced to 150c/302f. If you do this with a very low gas setting, there always is the option increasing the fire. Of course if the MET drops down too low as we're discussing, the profile gets wacky. This is one reason I'm an advocate of back to back batch roasting.

[edtbjon]

I think this belongs to another thread...

Thanks a ton, edtbjon! It dawned on me that even a quick shot with a laser thermomoter on the vent bowl, near the duct connection, would be revealing, if you have one of those. Cheers!

[edtbjon]

The ambient temp (in my apartment kitchen) is about the same. A few feet from an open window, but no big differences from previous sessions. This issue/possibility came to my mind though when I struggled with the first roasts.

I use the standard TC's provided with the machine, so that should be according to our "standards".

As you point out I do have to find my own profiles, procedures and corrections. I guess this discussion helps me and others doing that.

Another factor to consider is ambient temp. in your roasting space. What about wind if your roasting outside or near a door? ...

Which brings me to the turning point temp. and the idea of keeping it in a range that fits your style of roasting. I shoot for @90*C/194*f.  This is the point in the roast where I think the machine, beans, and BT thermocouple have equalized temps.

But roasters that use bare end thermocouples ...

If I'm charging 454g at 180-200c/356f-392f, 226g, the 1/2lb charge gets reduced to 150c/302f. If you do this with a very low gas setting, there always is the option increasing the fire. Of course if the MET drops down too low as we're discussing, the profile gets wacky. This is one reason I'm an advocate of back to back batch roasting.