Internal scorching is kicking my behind. Ideas? - Page 15

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
jakubx80

#141: Post by jakubx80 »

Vince_in_Montreal wrote: Hey Pcofftenyi, just wanted to give props where thanks are due. (Or something to that effect) I have been playing around with various times in various phases and just wanted to let you know this advice was spot on. This roast below was phenomenal. Plum, very berry-tastic. Strong obvious berry and not just a hint of berry.

Dropped at a lower DTR and lower temp. 13.2% weight loss which is less than my norm I had been averaging 14.5-15.5% loss. Full body I think that's to the 4min maillard made for a phenomenal cup of coffee. Cheers

image
I tried to achieve the same yesterday and was a bit uncomfortable as some FC pops were still occurring when I dropped the coffee.
I'll see tomorrow how it tastes.

Was your first crack over when you dropped the beans and is it in general ok and a good idea to drop when first crack is not completely over yet?

Vince_in_Montreal (original poster)

#142: Post by Vince_in_Montreal (original poster) » replying to jakubx80 »

Oh yea when I dropped these beans first crack is well under way but not quite done. Some beans were still cracking as I dumped them into the cooling box.

Cerini Coffee & Gifts: official US importer for Olympia Express
Sponsored by Cerini Coffee & Gifts
littlenut

#143: Post by littlenut »

OldmatefromOZ wrote:So ive had a few moments to catch up on this thread and i realise im just repeating myself....

: Ive roasted on a Huky, great machines BUT they have nothing to offer in how they are setup / work compared to Kaldi period. I even bought and used the Huky IR stove for about 1000 roasts with Kaldi, terrible does not work especially with the stupid heat deflector shield.

: I see you have re installed the heat deflector shield, sorry to be blunt but you will never get rid of the internal scorching with it installed. This is also the reason why your ROR has such a high peak then drops off at start.

Its a heavy 3mm thick SS DRUM roaster, ignore Kaldi marketing its rubbish and fails logic at every turn.
Hi Stephen, Thx for "repeating" yourself. I removed the bottom baffle from my Fortis several months ago because of one of your earlier posts. Tried it like that for a few months and didn't see a big benefit (nor any downside) so I reinstalled the baffle. What I did see was some additional radiant heating.

Skip forward ~6 months and I found my self wanting a shorter roasting time and a shorter Maillard (e.g. higher average RoR during Maillard), but I was right on the edge of scorching beans. I read this post about summing up your experience w/ removing the baffle and BAM I said to myself that that is exactly what I am looking for. I removed the baffle and roasted 10 batches today. Worked very well. Shorter roast times, shorter maillard, no scorching, Eliminated the steep fall-off right after the peak on the ROR Tb.

The purpose of this post is to say thanks for "repeating" yourself and why.

Regards,
-Tom

OldmatefromOZ

#144: Post by OldmatefromOZ »

littlenut wrote:Hi Stephen, Thx for "repeating" yourself. I removed the bottom baffle from my Fortis several months ago because of one of your earlier posts. Tried it like that for a few months and didn't see a big benefit (nor any downside) so I reinstalled the baffle. What I did see was some additional radiant heating.

Skip forward ~6 months and I found my self wanting a shorter roasting time and a shorter Maillard (e.g. higher average RoR during Maillard), but I was right on the edge of scorching beans. I read this post about summing up your experience w/ removing the baffle and BAM I said to myself that that is exactly what I am looking for. I removed the baffle and roasted 10 batches today. Worked very well. Shorter roast times, shorter maillard, no scorching, Eliminated the steep fall-off right after the peak on the ROR Tb.

The purpose of this post is to say thanks for "repeating" yourself and why.

Regards,
-Tom
Thats great, thanks Tom for sharing your experience.

Currently im thinking I was somewhat wrong about airflow.

Ive since removed the little chaff collection tray as well, so now i have a drum in a box with a flame.

Needed to replace front bearing was getting stiff after so many 1000s of roasts. I took the opportunity to do full disassembly and clean.
Then i put it back together without the hopper / exhaust on faceplate. Used a clear bit of plastic to cover it after loading with 400g green beans and then ran it just to observe what the agitation is like.
Ive spoken before about how i thought the internal drum is a good design, its much better than i thought. It creates a really nice swarm in the air over to the left (clockwise drum rotation). The beans spend very little time piling on actual drum surface.

This lead me to rethink airflow based on what Rob Hoos is teaching with the Bullet and anotherjims Environment Temp teachings over the years.

400g
charging at 205C
100% gas as beans falling in (1.0 kpa)
First 2 min no fan attached, hopper open for passive airflow (natural convection).
At 2 min attach fan duct using 1.5 on Kaldi chaff / fan box.
140 over 145C approaches start of yellow increase fan 2.0
155C end of yellow fan 2.5
170 over 175C one and only gas reduction to 70% (0.7 kpa - 0.65 kpa)
175 over 180C Increase fan 3.5 then let it go....

Depending on roast depth, fan goes to max (cooling mode) 15 to 30 sec before drop.

Im finally getting roasts that have no vegetal tastes, are a little lighter when ground compared to whole bean and highly aromatic.

Attached is an Ethiopian natural 400g.
Weight loss matches DTR at 13.3%
This is the first time ive got Eth natural to smell like top commercial roasters.

EDIT: Just to say that if one makes these mods then you are safe to use the roaster at its full capacity or maybe slightly more if you want a longer roast time. For me when I bought the Kaldi Classic their recommendation was 400g max batch size using Kenyan on YouTube video, which works great, gives solid data from the stock 3 mm probe which sits just left of centre in the face plate.

Cheers


User avatar
bradm
Supporter ♡

#145: Post by bradm »

OldmatefromOZ wrote: Currently im thinking I was somewhat wrong about airflow.

Ive since removed the little chaff collection tray as well, so now i have a drum in a box with a flame.
Curious how would you describe the preheating of the air before it enters the drum with your setup? Does it pass the flame first?

I ask because on my bullet the air gets little preheating and fan increases have a pronounced cooling effect. Ramping up the airflow for me requires a corresponding relative increase in power to preserve a nicely declining RoR. Maybe that's your point when you say "one and only one gas reduction"?

User avatar
CarefreeBuzzBuzz

#146: Post by CarefreeBuzzBuzz » replying to bradm »

Brad, then why make air changes except for maybe one post FC to remove chaff and smoke? I think many people here are using that method. I used to change at DE too but that was just another variable. I have settled on a setting with strong convection and just leave it there. I have a talking alarm in Artisan that goes off when I hit ON that reminds me to return my air to that setting.
CarefreeBuzzBuzz
___
Artisan Quick Start Guide
http://bit.ly/ArtisanQuickStart

pcofftenyo

#147: Post by pcofftenyo »

jakubx80 wrote:I tried to achieve the same yesterday and was a bit uncomfortable as some FC pops were still occurring when I dropped the coffee.
I'll see tomorrow how it tastes.

Was your first crack over when you dropped the beans and is it in general ok and a good idea to drop when first crack is not completely over yet?
I've dropped when 1C was tailing off before but I'm usually about 15 to 30 seconds afterwards, particularly if the drop temp is still within the acceptable range for the bean.

Some results were fine, others meh. All roasting is a balancing act of time, heat, and airflow so it depends quite a bit on the other parameters.

Flair Espresso: handcrafted espresso. cafe-quality shots, anytime, anywhere
Sponsored by Flair Espresso
User avatar
Brewzologist
Supporter ♡

#148: Post by Brewzologist »

bradm wrote:Curious how would you describe the preheating of the air before it enters the drum with your setup? Does it pass the flame first?

I ask because on my bullet the air gets little preheating and fan increases have a pronounced cooling effect. Ramping up the airflow for me requires a corresponding relative increase in power to preserve a nicely declining RoR. Maybe that's your point when you say "one and only one gas reduction"?
As an aside, if you are inclined you can run tests to see the general effect of airflow with your roaster. I ran an empty roaster at different gas settings I commonly use (e.g. low, med, high). For each gas setting I tried to find a fan setting that let me keep the BT constant at a particular gas setting. Say for example at low gas I was able to maintain 300F BT with a 30% fan setting, and at medium it I could maintain a 375F BT using 60% fan, etc. For any given gas level, once I got it to stay at a consistent BT, I would then increase/decrease fan to see what would happen at that gas setting.

This is a very general test that obviously will vary with environmental temp changes, etc. It also doesn't include the effect of having a bean mass in the drum. But it let me get a rough sense of when different air settings at different gas levels may have a convective heating, steady state, or cooling effect. Maybe it's useless information, but I found it interesting. YMMV.

EDIT: As a result of the above test I selected one average air setting for use in my roasting. I bump up the fan just before drop to evacuate smoke but otherwise don't mess with it.

User avatar
bradm
Supporter ♡

#149: Post by bradm »

Steve yes I did the airflow test that you mention after reading about the idea (your post?) in another thread. The test showed the bullet to be stable at fan level 2 (out of 12), and losing energy at level 3 and above. So I've since been following the method Michael mentioned: charging at fan 2 and increasing only to fan 3 later to better clear chaff once it starts to build. But I'm curious about Stephen's procedure, and wonder if his setup provides better preheating of the air than mine. Or, going a step further, if preheated air allows higher airflow which in turn reduces internal scorching?

OldmatefromOZ

#150: Post by OldmatefromOZ »

bradm wrote:Curious how would you describe the preheating of the air before it enters the drum with your setup? Does it pass the flame first?

I ask because on my bullet the air gets little preheating and fan increases have a pronounced cooling effect. Ramping up the airflow for me requires a corresponding relative increase in power to preserve a nicely declining RoR. Maybe that's your point when you say "one and only one gas reduction"?
Ive modified how my roaster sits on wok burner by cutting into burner housing. So the burner is about 1.5 inch from drum resulting in the tips of flames close to licking drum - the burner sits inside the drums housing (metal box).Have a look at this old thread where i posted pictures. Only difference is drum is painted matt black and im using the hopper as exhaust with the side port closed off because hot air rises straight up a lot easier...
Analyze my profile please

My understanding / somewhat answer your questions. Robs advice is basically leaving the Bullet on max power (is that P9?) and only stepping up airflow to manage the ROR. So you start at lowest fan for a couple of minutes then start stepping it up. I think this is for 500 to 600g.

If you read most of anotherjims old roasting posts here about Environment Temp this might help as well.

The way I see it now all these small drum roasters have no "environment" other than the drum itself.
Obsessive manipulation of an ROR graph on computer screen, through constantly reducing gas / HEAT is in fact baking / under developing roasts.
I could post at least 1000 perfect declining ROR graphs varying in length 7 to 12 mins that were completely underdeveloped and or baked and without ever blind cupping them so many people would say oh yes that's perfect coffee because one guy says so.

So, if you have a small drum and its quite thin there is pretty much no thermal capacity, it is the roasting environment and it makes sense to try and never reduce its heat source. Then manage the bean pile temp ROR with airflow to get the roast time / degree you desire. The tricky part is finding a batch size / time / finish temp that produces what you want.

Just to be clear, i dont disagree with Raos observations / dogma when it comes to large commercial roasters with huge amounts of thermal capacity to manage. It makes sense and ive tasted some pretty good medium defect free roasts from commercial roasters who do it right. Those that continue to crash / stall and flick are most definitely producing inferior product.