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Long roasts - more heat needed?
Aljaheejus
First, thanks to those who came before! With all the great information here in this forum (primarily) I have made relatively quick work of a BM roaster from an old Welbilt model.

I removed the circuit board and wired the motor directly. (Very even results with constant agitation.) Also, I wired the heating element separately and have used that to preheat everything and into the roast. It draws about 450 watts. My heat gun draws about 1,000 watts on high. With preheating to above 400 F, heat gun on high after charging, I am not getting to first crack until 12 - 15 minutes.

I've attached scope image from the wonderful Artisan software (manual input) tracking BT with a probe through the lid down into the bean mass.

Should I be able to ramp the BT up faster and be able to shorten the overall roast time by applying more heat?

Thanks again, David
Aljaheejus attached the following image:
05-png_2014_02_08.png
 
jkoll42
David

1K watt seems low for a heat gun. The junky Harbor Freight one I used to use put out 1500. With that gun and a simple lid I was able to reach 2C in 1# of beans in about 12 minutes unless it was really cold.

What is your ambient roast temp? Are you using a lid? Personally I would forget about the heating element and put those watts into a heat gun.
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
Suncountry
I don't run the heating element in my BM. My heat gun adjusts up to 1500 watts. I use about 80 to 85% of max output and reach second crack in about 12 to 13 minutes. Actually I back it down to about 75% after 1C to slow the temp rise. My amb temp is around 50 deg
 
Koffee Kosmo
The heat gun distance from the beans can effect heat distribution
Also consider a cover

KK
I home roast and I like it. Designer of the KKTO
Roaster Build information
https://homeroast...ad_id=1142

https://docs.goog...lide=id.i0
Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
 
David
"Should I be able to ramp the BT up faster and be able to shorten the overall roast time by applying more heat?"

Yes.
You didn't say how much the load of beans weighed, but by your graph I would conclude that you are not applying enough heat to get the profile your are looking for.

You have several options for shortening roast times.
You can up the power of your heat gun, you can bring its business end closer to the beans and/or contain more of the heat. And I suppose you could raise the ambient temperature, too. The other possibility is that you may be at maximum capacity for bean load, but I suspect that you are well within ordinary limits of a bread machine (.5 to 1.5lbs). The simplest solution is probably to go up in power on the heat gun.

Regardless of all that, here's my suggestion for an experiment to calibrate your roaster:

Alter only one variable at a time:
So, either before or after raising the power of the heat gun, try this.
Put the nose of the heat gun around 1" from the beans and run a batch.
Afterwards, look at the beans closely. Are there "divots" on the outside of beans? If so, then too much heat is being applied, for sure.

Next, either:
1) slice open one of the beans and see if the middle of the bean is the same color as the outside. If it is much lightrer, then the roast was too fast because the heat didn't have enough time to penetrate to the center of the bean; or
2) grind some of the beans and compare the color of the grounds to the unground beans. Once again, if it is significantly lighter, then the roast was too fast.

If the roast times are okay (what you are looking for) and the beans look all right in terms of color, then the problem is solved. (Unless it tastes like crap, which is another indicator that the roast was too fast.)

If you had divots or the interior of the bean is "rare" and the outside is "well done," then back off the nose of the heat gun a bit and repeat until you are satisfied with the results.
If the time is still too long to suit you, even after raising the power on the heat gun, then look at ways to contain the heat better (a lid or insulating the roast chamber.

Lather, rinse, repeat. Post results.
Happy experimenting.

Big David
 
Aljaheejus
Thanks for all the replies and great advice! I will try again and report back, with a photo or two.
 
Aljaheejus
Finally back with some photos and update on roast time. I've shortened the roast time by preheating to above 400F, and also modified the heat gun nozzle for better flow into the roast chamber. I think I should be able to stretch out the roast profile now after FC, if that's going to help with developing the flavors.

I was not able to get the same bean PNG Madan which I did all the initial roasts, but I did get the other bean that I had tried once with 454 gr. I'm back to 330 gr charges to keep that a constant. It is El Salvadorian, Santa Barbara, Peaberry, and it is an unusually small bean in my limited experience, so I don't know if that is making things more difficult to be consistent or otherwise. In the most recent roast, illustrated in the jpg attachment, I got to FC in 8 minutes. Previous, longer roasts with same did not generate audible FC.

I like the mounting of the gun in the lid, and if I'm getting enough heat to reach FC in 8 minutes, isn't that fast enough? I'm getting very even roasts, with consistent coloration through the bean.

Granted, larger loads will probably call for a more powerful heat gun, so the HF favorite, 1500 watt gun is probably in my future, dedicated and rewired for separate fan/heat control and someday control from an computer...

Any and all comments and suggestions are welcome.
Aljaheejus attached the following images:
07-elsal-zoom_2014_03_01.png 20140301_coffee-mods_0006mod_2_cr-web.jpg 20140301_coffee-mods_0003mod_cr-web.jpg
 
Lawnmowerman
Uh...any advice? I also prefer the harbor freight el cheapo 1500 w gun. I have 4, all broken or melted ... had them all apart. Strange thing i noticed was they dont all have the same curcuitry. Some have a dropping diode for the lower power setting. Others have an extra coil tap and no dropping diode. So if you rewire one of them this is something you could run into.
Ben.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
David

Quote

Aljaheejus wrote:I'm getting enough heat to reach FC in 8 minutes, isn't that fast enough? I'm getting very even roasts, with consistent coloration through the bean.

Yeah, that's plenty fast. Sounds like you are doing well.
Did you settle on a way to stretch out the time to 2C, perhaps to 12min?
 
Aljaheejus
Thanks. Well, I did reach FC in 8 minutes on that roast. Do you mean time from FC to 2C should be around 4 minutes?

Plan is to: just before FC: lower heat gun to low setting, turn off BM element, open vent. All or any combination to keep temp rising very slowly to stretch time until Drop.

Last night I tried a different bean and the roast behavior could not have been more different from the previous bean. This, Ethiopian SADI Cooperative bean immediately let off a great deal of chaffe; the temp rose very slowly and FC through SC occurred at much lower temp. Lots of smoke, very dark and oily results - not my preference...

Maybe my temperature meter became unstable or something. Lot's of experimentation is in order, and I'm going to try to stick to the same bean for a while.
Thanks! David
 
jkoll42
David

Yeah, 8 minutes is perfect to 1C and like you just thought, 1C-2C is ideal at about 4 minutes. For most beans in a HG/BM I like a 4-4-4 split starting point. 4 min to 300, 4 minutes more to 1C and 4 minutes more to 2C. One thing that works great to stretch 1C to 2C is the HF router speed control.

As far as that last roast, you probably had an issue with the thermocouple location in the roast chamber. It is pretty sensitive to location
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
Aljaheejus
jkoll42,
Thanks for the information. Just the kind of basic guidelines /target I need to stab at! (4 - 4 - 4)

My sensor probe was shorting out and not giving the correct temps last night, so it was way hotter than the reading I got - thus the very dark results.

Tonight I warmed it up for too long, it seems, and BT never dropped. I had to make a new temp probe also, so it may have been a little too high in the bean mass showing higher temps. Also, the rubber drive gear melted onto the bottom of the roast pan. I barely got the pan out with two pairs of pliers. At least I have enough heat!

I will look into using my variac - or get the HF router control to have more control. But first I would want to connect it only to the heating element, after separating the HG fan from the heating element. If I can keep the fan on while adjusting the temp it will be VERY helpful.
 
jkoll42
Haha - yeah, too much heat if stuff is melting.

Not sure what you are using for the TC but I've been using ones that I put together from Omega and they have been so durable and reliable. Not sure if part numbers have changed but here's what I ordered

omega.com

TT-K-24-25 -- 25' tc wire

SMPW-CC-K-M -- male end connector ("F" on the end if you want female for tc4)
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
MerlinWerks

Quote

Aljaheejus wrote:



Granted, larger loads will probably call for a more powerful heat gun, so the HF favorite, 1500 watt gun is probably in my future, dedicated and rewired for separate fan/heat control and someday control from an computer...


Hi,

Sounds like your roasts go similar to mine, 8-9 mins. to FC 12-13 mins to SC.

I don't know if you picked one up yet, but have you looked into modding the HF HG? Or do you have a link to some thread discussing it. I ask because I was going to do the same, but it appears that it is a DC motor and it uses some portion of the heating coils to step the 115 VAC down to ~ 15 VAC then diodes on the motor circuit board rectify that to run the motor. So in order to run the fan and element separately you need to supply separate power for the fan either AC or DC. I decided it wasn't worth the effort and simply turn the HF router control to minimum power at the end of the roast and let the HG run to ramp down a bit while I'm cooling the beans. Still curious if someone has come up with a nice solution to modding this though.
 
Lawnmowerman
You might consider modularizing. A dimmer and dropping transformer could be used to drive the motor. If could fit in a seperate housing. I havent really seen this done either but it could be done, but you might want to limit the sweep of the knob so as not to overdrive the motor.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
MerlinWerks

Quote

Lawnmowerman wrote:

You might consider modularizing. A dimmer and dropping transformer could be used to drive the motor. If could fit in a seperate housing. I havent really seen this done either but it could be done, but you might want to limit the sweep of the knob so as not to overdrive the motor.


That's the way I thought to go about it as well, still not sure if it would be worth the effort though.
 
jkoll42
In my experience it's not worth the effort. I used the router speed control direct into the gun. Yes, it reduced the fan speed but it didn't seem to matter.
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
Aljaheejus
Does the ambient temperature have a profound affect on BM roast times? I have been preheating lately, AND the ambient temperatures are 20F higher than some of the earlier roasts...
 
jkoll42
When I was doing 1# batches I found that cold (winter in pa) ambient temps put the heat gun at pretty much max output until 2C and slowed down the roast by a minute or so. When it was rally hot out in the summer I sometimes had to dial back the HG even before 2C. Profound affect.. probably not but definitely an affect.

I truly don't think preheating has a major effect beyond maybe 30 seconds. The thin metal of the RC really doesn't hold much energy.
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
David

Quote

jkoll42 wrote:I truly don't think preheating has a major effect beyond maybe 30 seconds. The thin metal of the RC really doesn't hold much energy.

Agreed. There isn't much thermal mass in that thin little shell.
Now, if you were using a cast iron pot, tha'd be different!
 
Aljaheejus
Unlike newer BMs I've seen, my RC is cast aluminum. Still, not much thermal mass, I agree. I tried too many new things all at once on last night's roast,- 454 gr charge, instead of the 330 gr), turned OFF the BM element upon charge, used new HF HG and new HF router control. Roast time became too long, though I had HG on high. I'm going compare the two HGs (though both are rated at 1500 watts I see). I also think I'll keep the BM element on again until FC. I want to be able to roast 454 grams...
 
Lawnmowerman
David. Ben here. I struggled with the same issues you are currently experiencing. I wasnt able to do lb roasts until I gor a better lid seal. Most important change. I also put a dimmer on the breadmaker element for more control. I can regularly do 500g plus batches. My old heatgun barely puts out 700degrees but with the extra heat control...well, the coffee is great! Could we have some more pics? May be able to better assist if you decide thats what you want to do.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Aljaheejus
Hi, Ben. Thanks for the note. I was poking around here last night and saw some of your posts and photos showing a lid that fit down onto the roast chamber top. My lid covers the outer/shell chamber (same lid lining the BM had) so the roast chamber is open at the top to the BM oven space. If I am correct that you and others are capping the inner roast chamber to get better heat control and higher temp rises (please confirm) then that's my next modification!

I like the window I have, so planning to make a sort of skirt down from the BM lid I have to partition the roast chamber from the BM oven space.

Will look into the recirculation/heat exchange features later! Nice mods you've made!
 
Lawnmowerman
You want the lid on the outer covering not the inner. And an exhaust port. My roaster uses deflected air outside of the chamber before exiting @the lowest possible point.
Lawnmowerman attached the following image:
cam00503-2.jpg

Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Lawnmowerman
All that extra stuff inthe middle is suspended by the lid. It is there to better contain and divert the air. And if you can see in the drawing, i used red crayon to show the likely airflow. Bread pan is enshrouded in hot air. And there are holes in lower lid to allow deflected hot air to travel there, too. Oh i almost forgot. Thanks4 compliments, and.. recurculator attachment element is old and tired. Only puts out maybe510 deg. F. Still does550g batches but im not using it since i found out how retarded it was. Now when i get a better element...maybe.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
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