Heat gun roasting - Airflow question

[salt]

Hi all,
Just got into "Coretto Roasting", and coffee roasting in general. Ive got a Makita 6020 heatgun, which is able to do in airflow in three settings - 150/300/500 l/min.

Was just wondering if any other heatgun users vary the airflow output of the heatgun while roasting, and why.

Cheers.

[sidewayss]

Re: Heat gun roasting - Airflow question

My Bosch 630 heatgun has 3 fan settings and i always stay on the maximum fan speed, which helps blow away chaff and get a thorough heating through the beans.
Id say stick to maximum fan speed to get a good result.
First crack should arrive anywhere between 10 - 14 minutes.

Perhaps i should try to do a roast at medium fan setting and see how the result is and then let you all know.

Gary at G

[scotchy1951]

Re: Heat gun roasting - Airflow question

Hi,
I use a two speed ryobi and always use max air flow and max temperature. I worry that max temp on lower air flow could cause element to burn out sooner. Always get a great roast.

[Dimal]

Re: Heat gun roasting - Airflow question

Gday Salt....

Before kicking off roasting with my Behmor (courtesy of a couple of very generous and prominent CSers), I always found that the best results (in the cup) were achieved when the air-flow was kept low heading into 1st-Crack and then only cranked up to full speed at that time. I also kept the top of the bread-pan covered too, just an entry for the heatgun nozzle and a similar sized hole at the opposite end to exhaust the air with chaff.

This created much sweeter brews in the cup and brought out a lot more of the beans intrinsic complexity too, so worth experimenting with. The great thing about the Makita heatgun, is that it uses a closed-loop control system to maintain the set air temperature, so full scale heat range is possible at both air-speed settings. Prior to the Makita, I used a Metabo heatgun and although an excellent unit, it didnt use a closed-loop control system to maintain air temperature so whenever the air speed was changed, I had to fiddle with the Heat Setting again to get the bean-mass thermal gradient back on track. Ive lost a lot of dexterity in my hands and this fiddling was becoming just too difficult for me to manage. The Makita though, is a piece of cake.... 8-)

Anyway, start off with smallish batches and just do some experimenting to get a handle on what works with your setup, then make adjustments a little at a time until you gain more and more confidence with controlling the roast process. Its a lot of fun and coupled with the rewards at the end, it takes a lot of beating.... Have fun

Mal.

[salt]

Re: Heat gun roasting - Airflow question

Thanks all for your helpful responses. I roasted my first batch of Ethiopian Gambella Sundried in a Breville BB400, uncovered, and found that when I set my HG to max airflow, temps in general rose fairly quickly, but I was wondering whether the max airflow resulted in ?stronger direct heat on individual beans, causing an uneven roasting effect on my 500g batch.

I think what Im really interested in, is really to understand the effects of HG airflow translated in the cup. Thanks for your suggestions Mal. What Ill do is Ill start getting to know the coffees that Im trying to roast, then Ill start changing the variables one by one.

And thats if I have enough coffee to experiment with!

[kesa32]

Re: Heat gun roasting - Airflow question

Hi , l run max airflow with my variable Temp HG and am achieving nice even roasts , later on Im going to try covering over the top of my BM and run a separate exhaust just to see how it goes
ATM I like being able to see and hear the beans while roasting , also the chaff blows out really well with it being open and the pedestal fan blowing it away from the setup ,
Do you have a DMM ? ( makes life a lot easier )
Cheers Ken

[JamesM]

Re: Heat gun roasting - Airflow question

Hey ya, I am also rosting in a bb400. Have only done two roasts so far, both differently. My first roast with no cover or lid, and not full temp, it took 17m till first crack, and 23min to 2nd. Using a cheap variable temp ozito.

Second roast I did full temp, and adjusted the actual bean temp by sliding a floor tile on and off the BM as required. I kept the roast to the profile shown in the fancy spreadsheet avail in the home roasting forum. I worked well, cracked earlier, but not too early.

500gm roasts work very well in this BM, some have said you can do 600gm. I am sure you can.

I would say keep your HG on max, use a lid or adjust the height of the HG to get the right temps.

Data logging temp will help you keep to a profile for consistent roasting, which I hope to be doing soon

[Dimal]

Re: Heat gun roasting - Airflow question

Yep...

Have to say that roasting with a mostly enclosed BM dictates that the Data Logger with Andys Roast Monitor Software is essential. Makes profile development and template following an absolute breeze. And yes, with a fixed heatgun position you do need to adjust the heatgun output during the roast progression unless a PID Controller is incorporated into the heatgun control, for example. This isnt really necessary since theres plenty of time available to control the roast manually.

Naturally, this level of fiddling isnt for everyone but if youre a bit of a geek like me, its a heap of fun and the rewards in the cup are definitely worth it. Could be worth trying out.... 8-)

Re: viewing the beans during the roast, it is possible to view the beans through the exhaust vent but in my case, I just bent up an old long-handled teaspoon into a "Trier" for sampling the beans along the way and that works very well.

I think the best thing you can do with home roasting, via what ever method one uses, is not to get stuck into a rut and always roast this way because it works. You might just discover that a little experimentation will allow you to tease out flavours from the beans that you didnt think possible - Thats why I do it....

Mal.

[JamesM]

Re: Heat gun roasting - Airflow question

Im excited after reading that!

[sidewayss]

Re: Heat gun roasting - Airflow question

You might just discover that a little experimentation will allow you to tease out flavours from the beans that you didnt think possible - Thats why I do it.

And thats why i love roasting with the coretto.

Thats a great idea Mal about the trier spoon trick.
Ive been wondering about using a cover for the coretto to find out if the end result is better.
This my next project.

Gary at G

[salt]

Re: Heat gun roasting - Airflow question

Hi , l run max airflow with my variable Temp HG  and am achieving nice even roasts , later on Im going to try covering over the top of my BM and run a separate exhaust  just to see how it goes

ATM I like being able to see and hear the beans while roasting , also the chaff blows out really well with it being open and the pedestal fan blowing it away from the setup ,
Do you have a DMM ? ( makes life a lot easier )
Cheers Ken

Hi Ken, yes I do have a DMM, but as Im still a newbie to the world of coffee roasting, Ive been using the DMM with the unenclosed BM. With everything going at the same time (heatgun, fan to blow away the chaff, BM) i must admit that it has been difficult to hear the beans "snap" at first crack.

Hence Ive largely been relying on a mixture of guessing when first crack is going to occur (roughly around 180degs C- from where my temp probe is), and looking at the colour of the beans, so i guess getting myself a long, bent, teaspoon would help.

I still havent gotten to enclosing my BM, as I still am currently obsessed with roasting as light as possible, post-first crack.

However, I did try Mals suggestion of low airflow, followed by high airflow heading into first crack. Not that I have anything much to compare to, but so far, its tasting promisingly good for my 2 last roasts, 500g of Ethiopian Guna Limu (CS5-6), and 500g of Peru Ceja de Selva Estate (CS5-6) (post-roast 2 days).

So anyways, a question for all. (at risk of sounding like an idiot -i have not much of an idea how heat behaves and roasts coffee)

In terms of enclosing the BM, Im assuming that the cover would promote the retention of ambient heat created by the heat gun, resulting in more even, and/or quicker roasts??

Cheers

[sidewayss]

Re: Heat gun roasting - Airflow question

In terms of enclosing the BM, Im assuming that the cover would promote the retention of ambient heat created by the heat gun, resulting in more even, and/or quicker roasts??

Thats something i been meaning to find out too but havent asked. Mal or Greenman can help in that regards. They have experience in using BM covers.

Gary at G

[JamesM]

Re: Heat gun roasting - Airflow question

I did my second roast using a tile (like one under your feet) which I slid over the BM and slid on and off the machine whilst measuring temp every 60 secs. Worked very well. looking forward to putting together a more appropriate cover. Although, the tile worked very well Its an easier way (at this stage) for me to keep the temp in the BM where I want it without adjusting the HG temp or height.

DMM hopefully will arrive today or tomorrow...

[GregJW]

Re: Heat gun roasting - Airflow question

In terms of enclosing the BM, Im assuming that the cover would promote the retention of ambient heat created by the heat gun, resulting in more even, and/or quicker roasts??

Retention of heat within the roasting chamber . Were not looking for quicker roasts (Im generally aiming at 10-12 mins 1st crack and 16-18 mins in total). But in reducing the loss of heat out of the pan you dont need to apply as much heat into the pan. Reduces moisture loss and prevents tipping / scorching.

I just use some alfoil over about 80% of the opening. I particularly reduce my airflow after 1st crack (just give it a few occasional bursts to clear out chaff and smoke) to have a slow controlled ramp up to 2nd / finish.

Hope it helps. Greg.