Beans getting stuck when high airflow

[Adondo]

Hi.. I've seen a few posts of this way back of the beans getting stuck as a result of high airflow, but no real solution has been found except lowering airflow? Currently I'm roasting a lot of naturals like the Ethiopia aricha and Ethiopia Idido which contains much chaff, forcing me to increasing airflow to suck it out. The last couple of roasts I managed to have enough airflow to remove the chaff, but then the result was reaaally smokey. Now that I further increased airflow to tackle the smokey flavour about 15g of coffee gets stuck continously during the roast, making me wiggle the huky a little to get them down again. But just after a few seconds they return.. Does anyone have a solution to this issue? Im really interested in roasting these coffees since I do enjoy them a lot and would not like to give them up just because of this.


// Robin

[edtbjon]

It seems like a common problem with the T model. I've seen some very horrible solutions to the "stuck beans" problem from people who thought that roasting coffee was a piece of cake. Anyhow...
The reason for the problem is (I'm guessing here...) the somewhat sharp angle of the T and some other factors. But what to do about it??? I used a T for a year and learnt how to circumvent the problem, but it takes knowing the roaster and good fan control.
First question: If you analyze the stuck beans, are they all fully roasted and sucked up into the exhaust in the very last phase of the roast? ... or are there green and yellow beans there too?
For the green/yellow beans I found the solution to be a guard made out of foil, to cover the exhaust pipe when pouring in the beans when I started the roast.
Some beans will sit in the exhaust due to the exhaust pipe to front plate construction. I usually lift the roaster a centimeter or so (with the tryer handle) and drop it so that small impact shakes down to the drum again.
If memory serves me you got some kind of fan controller which with the issues that are obvious with the T construction, needs some special care. In short, don't use too much airflow. I usually set the max airflow to some 7-8 m/s (measuring the airflow at the bottom of the T of J pipe...). That translates to some 55-60% of full whack on the Variac.
The passage of chaff past the damper is a bit narrow. It's good practice to wiggle it now and then, so that any stuck chaff will get sucked down to the chaff sieve.

All in all, the Huky is a very nice piece of machinery, but maybe not a complete package where you press the button, adjust a few times and you're done. (That takes a lot of more money...) For the money spent you get a very competent roaster, just needing you to being able to figure out a few quirks, while learning how to roast. So far it's taken me well past two years to learning how to get a decent roast. Learning the roasting bits of the whole package have been the easy bit and the Huky have been up to the job all along.

[Adondo]

The beans that get stuck are yellow-very light brownish. I used to tilt the machine too, and do that every now and then to prevent beans getting stuck. The problem I found though is that my RoR goes out of phase really fast. I was in the process of buying a fan controller but ended up not doing it actually. Aye, after some consideration I'll just let the beans get stuck. All in all it'll only cost me 130 SEK /year. To fix this I would need to re-do the entire front pipe, probably giving me like 3-4 year in payback time lol. I wish I could use less airflow but my roasts ends up very smoky as the chaff gets completely stuck in the middle of the T-pipe.

Thanks for your input :-)

[edtbjon]

Well, roasting with a blocked exhaust pipe will throw consistency out of the equation for a start. It's like driving a car with a banana in the exhaust pipe.
Anyhow, you do need some kind of fan control. The reason for recommending Variac was probably due to some early user having one at hand. A Variac is overkill, but some kind of router speed controller (not very common in Sweden) or a dimmer with a relatively large control knob will get you started. You should be able to find one for less than 100:- ($10). You can then check and find three settings with a cig.lighter.
The yellow/pale beans indicate that the beans get into the T when you charge the beans. Try to make a 20cm strip of flexible cardboard or alu.foil some 5-6cm wide which you curve so that it goes in the back of the charge top damper/chute. Put the strip so that it covers the exhaust when you charge the beans. Then take a deep breath and puff into the exhaust, so that there are no beans left anywhere in the exhaust.
I tried experimenting with the damper for airflow control but I don't think it's a good idea for such a narrow exhaust. I always had serious problems with chaff clogging.

[Brent]

This might be a bit off topic. If so, I can start a new topic. Don't want to hijack the thread.
I've noticed, watching some videos of people roasting with their Hukys, that by the end of the roast,  they are using close to, or full fan. (The Mill City vid comes to mind) Isn't that a lot of fan power for a small drum?  😱 My fan tops out at close to 15 m/s. On one hand, I can see how 15m/s fan speed could suck beans out. Then again, if it's not stalling the roast then maybe it's ok? Or do Huky fan speeds vary?

It seems to me that the perforated would also not need as much fan as the solid drum. Is that correct? I find with the perf. drum (with grate closed ) as little as 2.5m/s to 3m/s of airflow - measured at the fan end as Hank did in his video - will  affect my ET, with BT quickly following. I use that much just near end of drying and about 5.5m/s around first crack with a 300 to 350 gram charge. Watching some of the videos I'm beginning to think I may not be using enough fan, but I'm not noticing any smokey flavors in the cup and I seem to be getting the chaff out of the roaster. Although, around 4 m/s seems to be enough to give me the slight lean of a lighters flame towards the trier hole, that Rao talks about.
I'M using a dimmer switch...continuous dial type, not a slider. I have to turn the dial up about half way to get the fan going, but then I can set it quite low while drying with damper closed.

[hankua]

Brent
You need to NOT follow what anyone else is doing; just keep using your intuition or common sense managing airflow.

Airflow is a tool just like heat, and because the Huky fan is dual purpose drum cooling and bean cooling; it's overpowered.

[Brent]

Thanks for the suggestion Hank.  I'm just trying things as I go along as you suggest, but am open to ideas or suggestions too. 
I'll just keep reading the earlier posts in the forum too. Lots of info here and at HB

[hankua]

Your welcome!

One thing I noticed about fan control especially with the dimmer; it was helpful to rev the fan up before using a low setting.

Using an anemometer to measure airflow there was a minor difference between say 70% and 100%, with the solid drum kit.