suggested temperature for 2kg HG

[an3_bolt]

With regards to the thermocouple probes - I tested all sorts of K types from exposed tip, welded tip/grounded, ungrounded, with various lengths and sheath diameter/thickness. The optimum results from my research - aiming for rapid response time and accurate measurement of bean mass temperature, gave a relatively narrow stainless diameter probe, grounded tip, yet only half the length of what you indicate.

I also noticed it only took (off the top of head with consulting my notes) around 25 mm from the interior of the face plate for the probe to read correctly - provided it was encapsulated within the flowing bean mass.

The other indicative of higher turn around temps and low FC/SC readings was the thickness or diameter of the stainless sheath of the thermocouple - ie increasing the response time. These particular probes would also consistently provide different FC temps for running the roast of the same bean in a different manner ie lower FC for a faster roast due to slow response time.

I also have placed my bean temperature probe in the inner screw hole of the window and an environmental probe through the bean chute adjacent the exhaust ducting from the top of the drum area. I also use a 3rd beaded style probe as a crosscheck in the bean mass - but I do not bother recording it - just a crosscheck. Since I am using grounded probes for my main ones - I have found it beneficial to insulate the probes from contact with the metal.

Does this count as thread hijack - or educating that one mans charge temp. turn around temp will not be the same as anothers......especially when the FC/SC temps are out by a large margin?

[TC]

In my experience, turn is dictated very much by probe length and placement.

Of Andy's kit, I have experienced best results with a 100mm probe placed as far as possible into the top left screw hole of the door and appropriately insulated. High turn readouts with low FC and SC numbers are often observed with the short probe. FWIW, a turn at 70deg sounds a whole heap better to me than one at more like 90 deg. Agreed that the HG probe is really only of use for cutout.

Cheers

Chris

[an3_bolt]

Hi Mike,

I have actually settled on 750g loads for my Hg 2kg - more so that by the time I roast a couple of batches - I am always giving some away so I can do the next roast. At 750g I find it touchy but very responsive.

I spent several months fine tuning thermocouples for mine....which has paid off in a very accurate setup. The HG one is really only good for the overtemperature cut out system in the gas train.

Generally my soft beans I drop at around 150-160 and the hard ones at about 180-185. Gives a bottom out around 70. Take it with gas from there to where ever you want to end up.

Realistically when I have tried smaller batches, I find it becomes very touchy on the gas and somewhat inconsistant in the results. I agree with the 1 kg load is very repeatable and responds well to a light touch. Having said that - the LPG gas system in mine has the ability to do whatever you want.

Took me a while to get mine all sorted out (the operator that is) but a great little machine capable of pulling some serious punches.

[speleomike]

Hi all

I also have a 2kg HG. My temp probe in a similar place to you summercrema - in one of the screw holes of the window - mines in the top screw hole.

I do a 1 kg roast each time. Sometimes I will do 1.25 kg but never less than 1 kg. I tried low batches a few years ago when I got my HG and I found even 750 grams was a bit low, 550 grams would I think be far too low. I picked 1 kg as it handles that load well and I like to keep one variable the same for consistency.

Talk Coffee said "When I roast, the aim is to maintain a turn temperature which is about the same- regardless of charge. I do this by varying the drop temperature accordingly." I do the same. I don't want the lowest temp (this is the turn temperature) to ever get less than 100 C. So I usually drop at 230 C for a 1 kg standard load. If the night is cold I'll raise that drop temp to 235 C or if it's hot during summer might lower it to 225 C. After I drop I keep a look out to see if the temperature is dropping at the right rate - too fast and I'll keep the gas flow up.

Once on the climb up I just vary to gas flow to get my profile to FC and SC - not many other variables then so it's easier.

Mike

[TC]

When I roast, the aim is to maintain a turn temperature which is about the same- regardless of charge. I do this by varying the drop temperature accordingly.

Once you take this approach, it's not hard to roast to your chosen profile regardless of drop. I can roast a kilo in my roaster to mirror the profile used for 10kg. My opinion is that this is one of the pathways to consistency.

[greenman]

Hi summercrema if you are in Perth we have cupping at Dimattina in osborne Park on Friday at 1pm--cone along!!

[summercrema]

Hi Greenman,

Met you at beanology outside the lecture room a year ago, thank you for sharing your experience with me above. So with a smaller batch roast FC will reach at lower temperature. What have you been roasting lately? I know you have tasting class every now and then perhaps one day I can drop by to the class.

[summercrema]

Hi Chokkidog

I have the SS probe fitted close to the viewing glass

[greenman]

On my Torrefattore 2kg the temps on a 400-500g roast will vary compared with a 1.8kg load, my bean probe is low down on the door and smaller batches don't cover the probe sufficiently to get an accurate reading. On a 1.8kg load I reach 1C around 200-201C but smaller batches I reach 1C from 187-low nineties.

[chokkidog]

I guess the important thing is that you are getting results that are to your liking.
Try not to get hung up over the temp readings, as long as you are getting real time
data that correlates to roast events, you are fine. It's what's in the cup that counts.

550g roast in a 2kg is only 27.5% capacity, I would have thought the sweet spot would be more like a
1.75 kg charge weight, so it's possible that the reading might change with a bigger bean mass.
On my roaster (5kgs) it's pretty much the same; 600gms or 4.5 kgs.

Despite what I said first, I'm aware that we want to feel as tho' we're doing things 'right' and prefer to have our
roast temps as close to theoretical actuals as possible. Where is your TC probe located? How far into the bean mass
is it? Have you tried moving it? The lower right hand sight glass screw is where mine is, I also have a spot in the door
which I can use. You can spin the drum by hand to check if the mixing paddles will hit the TC probe.

As far as charging your 2kg roaster with 2.5kg …………… why? It's not designed for it.

When working out your load temps, unless you have a 100% climate controlled roasting environment 24/7 then
you will have to rely on experience and historical data and work it out according to ambient temps of air and beans,
as well as charge weight, in order to achieve a consistent turn temp. It's actually pretty easy, once you are doing regular roasts.

Cheers.

[summercrema]

started roasting with my 2kg HG for two weeks now, done several 550g roast already results are improving.

Right from the start I have installed a 10cm SS temp probe to the HG even so there is still a 7 - 10 degree celsius difference (lower) compared with my hottop B probe reading, generally Hottop FC happens around 195 - 200 degree, but on the HG FC happens around 18x - 187 degree celcius, I found HG is noisier than the Hottop so SC is very hard to hear and I am still trying to find out how to read the starting of SC from the Roast Monitor chart, on my charts it is a slow rise from FC to SC I unload the beans between 215 - 217 on the Hottop so take 10 degree off that with the HG, generally keeping a 2 -4 degree per minute rises between FC and SC. Looking for that little change in the curve .

Another thing is I like to do a 2.5kg roast and what should the load temp be for that size?

thanks