Yet another handsfree HG setup: HG/iRB

[Javaphile]

Re: Yet another handsfree HG setup: HG/iRB

To keep chaff out of the HG and keep it cool, Belinda placed a fan which blew across the top of the Corretto and directly onto the HG....

Ive been using it since day 1 with the Corretto and it works perfectly!! No chaff near the gun and the heat gun exterior remains quite cool even after 20 minutes of roasting.

Worth a try.

If Arcticroaster sets up a fan blowing accross his bowl he will most likely have a heck of a time finishing a roast in decent times. Remember the ambient temperature where hes at.


Java "Knows about the cold!" phile

[JavaB]

Re: Yet another handsfree HG setup: HG/iRB

To keep chaff out of the HG and keep it cool, Belinda placed a fan which blew across the top of the Corretto and directly onto the HG....

Ive been using it since day 1 with the Corretto and it works perfectly!! No chaff near the gun and the heat gun exterior remains quite cool even after 20 minutes of roasting.

Worth a try.

[Bullitt]

Re: Yet another handsfree HG setup: HG/iRB

Quote from arcticroaster
" Thanks Bullit for all this comparative info - and nice to have somebody elses experiences to share with.

Is this your main roaster-setup you use ?

About the HG sheetmetal shield - do you have somewhere a pic of that (or even of your whole setup for that matter) ? Sounds interesting to me.
I havent looked into the inner workings of (my) HG, but how does this chaff actually impact lifetime ? Does it gradually stuff up the airpath or is the burning off somewhere during passage through heat elements which is the issue ? On mine I noticed that the chaff seems to get flushed through the HG and comes out as sparks => a problem ? If so I may look into your shields, possibly also for the drilling machine air inlet where even more chaff flies around.

Cheers, Peter"

OK Ive been meaning to get some photos and put a post in on the beast. I had just got it going when the BM thing started and really took off.
I started roasting with a standard popcorn popper, which was soon modified, with help of an electrician, so that the fan motor had a separate transformer, with 4 different voltage taps being used so that I had a 4 speed fan, and we used an old simmerstat from a stove to be able to switch the heating element (turns out you dont need a simerstat, any suitably rated switch will do). I also fitted the thermocouple straight down the side so that it was in the bean mass. Oh and the obligatory chimney. It was relatively easy to get repeatable roast profiles, but capacity was a bit small once friends started wanting freshly roasted beans.

The HG/drum roaster was developed after looking at a manually intensive set up using a colander sitting inside a bowl, and hand stirring.
The HG set up is currently my main roaster, although I have recently used the popper for some decaff roasts as Im finding them difficult with the heat gun. Anyway enough rambling.

The extender nozzle and shield were later add ons to the HG. Main aim was to move HG a bit further away from the hot bean mass, and the chaff.
While some chaff will blow through, over time some will build up inside and eventually contribute to some sort of failure, typically due to heat build up. Additionally, recirculating warmed air from the drum area will also cause raised internal temps, eventually fan motor can burn out.
The shield helps to reduce chaff being sucked into the gun, and recirculating of heated air from around the drum.
Yes it would be wise to look at something similar for your drill as well.

I will see what I can do about postinmg pictures of my set up this weekend.

Regards
Bullitt.

[Bullitt]

Re: Yet another handsfree HG setup: HG/iRB

Quote from arcticroaster,
"A final basic bean-science question for curiosity: has anybody of you ever measured the emittivity of green / brown beans at the various temps occuring during the roast, i.e. how large actually is the resulting temp meaurement error coming alone from error in the eps = 0.95 assumption ? e.g. 10 deg error @ 200 C is only 5% and could that be easily coming from wrong eps ?

Once I have the gear, I may do that actually to see if it make sense to use some eps correction tables (in above device you can adjust the eps). "

Well, the IR gun that I have been using is fixed at 0.95, although I do have access to a more advanced model which is adjustable, and had been thinking recently that I might give it a try to see if I can get better accuracy.

Apart from that I did once try to see how the readings compared to the TC that is mounted in my popper, and I found that first reading would be around 10deg lower but it would range up to same reading over 10sec or so, which I thought at the time was something to do with the exhaust heat coming straight up at the IR gun. Unfortunately I didnt wait and see if the IR gun temp kept increasing, or stabilised.

The drum arrangement is potentially better, due to relative airflow directions and so on.
Now youve got me really thinking about playing with the other IR gun that is adjustable, but I can advise that the standard setting of 0.95 generally will give a lower than actual temperature, but it seems to be consistently low, so is useful for comparison of progress.

Rarely do I finish a roast on temp, usually I finish on first snaps of 2nd crack, through to 20 sec rolling 2nd crack, depending on the bean type.
However as you noted, it is useful for tracking the temp between 1st and 2nd crack so you can maintain a slow increase.

Regards
Bullitt

[Javaphile]

Re: Yet another handsfree HG setup: HG/iRB

One of the big problems with using the IR on my setup is that I cant hit the main bean mass with it. As you can see in the pictures (http://coffeesnobs.com.au/YaBB.pl?num=1121040424/34#34) the barrels are relatively small as are the openings in the front lid. The barrels rotate at roughly 40-50 rpm and the main bean mass is up against the front lid. As a result when taking a reading with the IR during a roast theres a lot of metal in the beam and the beans are flying by resulting in the indicated temp varying wildly. When the beans hit 2nd crack and start smoking more the fluctuation is even worse. With no beans in the barrels the temp reading is rock solid at all temps. Because of all this Ive found that with my setup the IR is not even usable to get an idea of the temperature slope to any usable degree.

With your roasting setup it looks like youll have a nice clear shot at the main bean mass and so the fluctuations should be quite a bit less than here. It will be interesting to hear how stable the indicated temperature is with your setup.

On most barrel roasters that Ive seen the temp probe is on the lower area of the front of the roaster and sits in the bean mass just out of reach of the vanes. Some day I hope to have such an arrangement on mine. Some day!


Java "Still playing with his toys" phile

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Hi JavaB, Javaphile and Bullit,

thanks for your guidance on the IR bean-thermometry, very helpful info!

After thinking your comments through and also reading a bit up on IR temp measurements in the meantime, I think I will give it a try. I am considering this device: http://www.conrad.de/script/infrarot...eter_ir-37.sap.

Just like Bullit, I dont have either any ideas how to put any TC in a stable manner into the bean-bed, when these vanes come by (actually the TC tip gets even caught by the vanes). Also the idea of just attaching a simple "standing" oven thermometer into the bowle center axis does not work - to few beans flow around it and it also greatly disturbs the bean flow.
[BTW, how do you mount the TC inside a drum , same story ??)]

Even with the large inaccuracy of the IR on the absolute temp, I would still probably get some decent RELATIVE measurements and some indications of the temp rise slope. At the moment I am flying blind, I even dont know if I drive the roast into stall, ie drop the temp between 1st / 2nd crack . So it only can get better.

I guess the motivation for quite accurate temp readings would be some roast repeatability. But then I dont think my setup here is anyway good for that; the wide open, unshielded bowl, as nice as its to watch, invites winds and is generally probably difficult to control anyway. So I should be OK with just rough up/down type of indications etc. Maybe one can also over time learn a bit more, how/where the IR inaccuracies build up.

I have about 3 cm measurement spot on either side of the HG aiming center, the "hot" downstream and "cold" upstream side. I guess coffee beans are very poor heat conductors so the HG will boost up the IR-measured surface temp as Bullit pointed out. Maybe then I should go for the "cold" side.
Above device has 6:1 optics, so distance would be around 18 cm which is where the HG holder is, so I could try to mount the IR thermometer there as well, at least its out of the HG airstream.

I let you know progress in this area, once the IR thermometer arrived here (will take some 2 weeks time or so).

Anyway, its fun to learn about all this IR physics, quite intriguing, and perhaps in the future we use the IR-Corettos, then all the learnings apply as emission=absorption and you get all the same issues again in the other direction ...

A final basic bean-science question for curiosity: has anybody of you ever measured the emittivity of green / brown beans at the various temps occuring during the roast, i.e. how large actually is the resulting temp meaurement error coming alone from error in the eps = 0.95 assumption ? e.g. 10 deg error @ 200 C is only 5% and could that be easily coming from wrong eps ?

Once I have the gear, I may do that actually to see if it make sense to use some eps correction tables (in above device you can adjust the eps).

Cheers, Peter, becoming slowly a black-bean radiation addict ;D

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Hi arcticroaster,
Also I have recently begun using a small extender nozzle, and added a sheetmetal shield around the HG to minimise the possibility of the HG sucking in chaff, in an attempt to extend the HG life.

Thanks Bullit for all this comparative info - and nice to have somebody elses experiences to share with.

Is this your main roaster-setup you use ?

About the HG sheetmetal shield - do you have somewhere a pic of that (or even of your whole setup for that matter) ? Sounds interesting to me.
I havent looked into the inner workings of (my) HG, but how does this chaff actually impact lifetime ? Does it gradually stuff up the airpath or is the burning off somewhere during passage through heat elements which is the issue ? On mine I noticed that the chaff seems to get flushed through the HG and comes out as sparks => a problem ? If so I may look into your shields, possibly also for the drilling machine air inlet where even more chaff flies around.

Cheers, Peter

[Bullitt]

Re: Yet another handsfree HG setup: HG/iRB

Hi again,

coming back to the unfinished thermometer busines of this contraption; I wonder if IR thermometer is the only reasonable solution in this case of the rotating bowl :-/. I havent studied this case yet, just some quick thoughts dotted down here, but knowing that some of you CS are using it I would be happy to get any fast guesses how it work for this particualr gadget:

- beans with high emittivity are gainst backdrop of SS bowl lwith ow emittivity ==> problems for accuracy when the IR thermometer "sees" parts of the the "cold" bowl ==> too low temp ?
- the far hotter air from the HG wont disturb the measurement (transparent) ??
- one needs to figure the distance one can give the IR thermometer from bowl, so that it doent get grilled by the stream from the HG; the cheap ones only have 1:1 or 1:6 optics
- smoke in this gadget goes nicely up and fan disperses it ==> smoke no issue ?
- prices seem to be from < 20 .. 45 EUR upwards ==> sounds quite OK for me
- no datalogging for the cheaper ones
- why arent you using IR thermometer in your other setups more often, wouldnt it work also Ok for e.g. BM vessels in terms of better estimating the BEAN temp rather than AIR temp? I mean is IR thermometer the best approach for all fluid-bed / hot air roaster approaches ????
- any good pointers / links for further study ?


Thanks, Peter

More on this,

I also have a popcorn popper with a stainless steel encased thermocouple mounted in it, which gives reasonable indicationof bean temperature as long as you have the probe buried in the bean mass. I have done one test where I compared the thermocouple readout with the IR gun and IR gun gave very similar temperatures but appeared to be slightly affected by heat haze coming from the beans, however it was directly in the exhaust fromhte popper.

The HG/drum roaster I use has HG pointing down at approx 45 deg, and I can aim IR gun at the bean mass. Yes as mentioned before, there is some ranging, or instability of the temp, but it does seem to vary with the particular bean type. Also I find that the temps displayed tend to be 5-10 deg below actual bean temp, and I have had some difficulty repeating roasts using this method, as sometimes the temp of first snaps of 2nd crack can vary quite a bit for same bean type. One issue seams to be the hotter beans on top of the mass, compared to the average mass temperature, as the outside beans get teh full blast from the HG.

I have thought about trying to fit a thermocouple device into the drum but so far have come up with no solution due to having to avoid stirrer vanes and the HG output etc.

Regards
Bullitt

[Javaphile]

Re: Yet another handsfree HG setup: HG/iRB

Yeah Im afraid that the cheaper IR thermometers are only going to be useful for getting a rough idea of the actual bean temps for the very reasons you mentioned Arcticroaster. They will most likely be more accurate when used with a BM type set-up or yours than in my sample roaster as you will be able to keep the beam on the bean mass better. They probably will still be to inaccurate to use for actually determining the degree of roast though.

Nice to hear that yall are able to receive and enjoy PHC. Its been a classic around here for more years than I care to remember. ;D


Java "Wandering off to Lake Wobegon" phile

[JavaB]

Re: Yet another handsfree HG setup: HG/iRB

Peter,

Javaphile posted a response some time ago when this was mentioned in the BM roasting thread....

Apparently a combination of smoke, the "heat haze" from roasting etc makes these inaccurate. There are probes which will work (read expensive!!) but the elcheapo ones wont work properly for this application

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Hi again,

coming back to the unfinished thermometer busines of this contraption; I wonder if IR thermometer is the only reasonable solution in this case of the rotating bowl :-/. I havent studied this case yet, just some quick thoughts dotted down here, but knowing that some of you CS are using it I would be happy to get any fast guesses how it work for this particualr gadget:

- beans with high emittivity are gainst backdrop of SS bowl lwith ow emittivity ==> problems for accuracy when the IR thermometer "sees" parts of the the "cold" bowl ==> too low temp ?
- the far hotter air from the HG wont disturb the measurement (transparent) ??
- one needs to figure the distance one can give the IR thermometer from bowl, so that it doent get grilled by the stream from the HG; the cheap ones only have 1:1 or 1:6 optics
- smoke in this gadget goes nicely up and fan disperses it ==> smoke no issue ?
- prices seem to be from < 20 .. 45 EUR upwards ==> sounds quite OK for me
- no datalogging for the cheaper ones
- why arent you using IR thermometer in your other setups more often, wouldnt it work also Ok for e.g. BM vessels in terms of better estimating the BEAN temp rather than AIR temp? I mean is IR thermometer the best approach for all fluid-bed / hot air roaster approaches ????
- any good pointers / links for further study ?

Thanks, Peter

[Bullitt]

Re: Yet another handsfree HG setup: HG/iRB

Hi arcticroaster,
I built something similar, using a wiper motor out of an old car to turn the drum, also used a colander as the roast drum, but encased it inside a mixing bowl, to try and keep some heat in. I have also tried a cardboard box as a partial wind shield to help smooth things out a bit.

I also have noticed some uneven roasts, but it does seem to be as much to do with the bean variety as some varietyies always seem to be uneven, and some others seem to be much more even. However stirrer vane configuration is an ongoing development also with mine.

My heat gun is usually further from the beans, than what yours appears to be, and I can conistently get first crack around 11-12 minutes and 2nd crack or the start of it around 14-17 minutes.

For the time being I am using a small Infra Red Heat Gun to estimate the temperature, it is not very accurate and usually has a problem with ranging over anything up to 10 deg, but does help to know whether you are on track or not, and is usefull for the time between 1st and 2nd crack where you want to slow things up,...helps with being able to move the heat gun further out, and still maintain a slight heating rate, (generally because heating rate has slowed, the ranging effect is minimal at that stage).

Mine will work with batches from around 200 - 325 grams (upper limit being determined by the size of the colander), best roasts generally seem to be closer to the 300gram size.

Also I have recently begun using a small extender nozzle, and added a sheetmetal shield around the HG to minimise the possibility of the HG sucking in chaff, in an attempt to extend the HG life.

Great job, and great to see some one else had similar idea to mine

Regards
Bullitt

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

LOL Yeah I know all about not much sun in the winter. Im not nearly as far north as you are but our winters here are every bit as severe. It looks like February is your coldest month with an avg high of -3C and an avg low of -6C. Janurary is the coldest month here with the avg high being -6C and the avg low at -15C. December is not far behind with the avg being -3C/-12C and February averaging in at -2C/-11C. Weve been having an incredibly warm fall and winter here as well with the temp only in the last few days getting down anywhere near normal.

oh, now I see from your profile that you are from Minnesota. Well, we know everyhting about YOUR tough winters, as we are since years regular listeners of "Prairie home companion" and the latest ice-fishing incidents from lake Wobegon the show of which is re-broadcasted here locally every Saturday.

On your roasting setup (BTW I love the klugeness of it! ) Id be trying to slow the roast down, by quite a bit. To get maximum flavor from the beans try hitting first crack around 10 minutes or so and finishing up at 14 or 15 minutes. Youll be surprised at the difference it makes in the cup.

thanks, I will aim for that and hopefully it will not take the whole winter of bad-coffee drinking before I get the HG controls right ...   :

Cheers, Peter

UPDATE: just completed roast#4, now slightly too slow: 1st crack @ 11:30, 2nd rolling at 15:00, roast off after 16, looks OK. We are getting there, we are getting there ...

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Hmm... My Mum gave my Nephews some Meccano a couple of Christmas ago (they still sell the full-on Metal stuff here).  I wonder if I could convince them to have a go at building one of these for me?

Juls

Better get hold of it fast, especially if covered with dust and thus easy to horse-trade ... You never know, prices for these sets may suddenly rise in Australia, I heard, there are some real coffee fanatics out there

Cheers, Peter

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Does it come in a lego version? 8-)
RH

Youll need to find out for yourself rayzurhed ;we gave all our Lego sets away, so I wont go down that road ... and besides I need to learn the roasting trade first ...

I was in the beginning thinking to use a wood construction + roller bearings (with mounting screws attached), as I am here able to track down & process wook parts easier than some exotic metal parts.

As always one needs to watch possibly high temps at the shaft when interfacing with plastic stuff. This very thin shaft I used doesnt get that hot in a 15 min run (you can touch it), so the plastic-based gear wheel wont melt away. I anyway added these pathetic cooling fins to the shaft ...

For alternative constructions one should probably fix the drive motor first (like windshield wiper motor or whatever else motor as discussed under the various BBQ motor threads her at CS), as this then will dictate the gear-down (if needed) and motor/drive space and transmission / shaft requirements for the rest of construction. Due to this ~45 deg inclination this may be a bit more tricky then for horizontal BBQ style drum or vertical bowl-stirring schemes.

When using a drilling machine or simlilar you must gear down as otherwise the bowl rotates so fast (even at low rpm setting) that the beans just stick to the wall ... Another idea for gear-down I had was to cannibalize the metal toothed-wheels from a hand drill ...

When I initially started making a list for wood construction + roller bearings , I noticed that this requires some really drawing&planning and would likely result in multiple visits to HW stores when things dont work out as planned, so this Meccano set was a blessing as everything fits to each other. I just went ahead without plan and got the thing out after two (long ) nights ... With Lego this flexibility would be similar, I guess. Aestetics is then another question, but hey, all we want is a good cup of coffee, right

Oops, a long sermon for a quick tease :-[

Cheers, Peter