Corretto questions

[bolb]

Re: Corretto questions

Hi Greenman & TG
How far off the bottom of the bowl are your probes?
I am using the thermocouple from the DMM drilled through the side of the BM and bowl, i havent measure the distance of mine from the bottom of the bowl but it wouldnt be that far off the bottom though.

I used to use a flexible probe but found i had issues in keeping in the same position all the time and the move to the rigid probe overcame that.

Mal

[Thundergod]

Re: Corretto questions

Mine is close to the bottom but the HG is in the opposite corner.
That way I figure I get a truer reading.
If I move the HG closer to the probe the increase is immediate and drops just as fast as I back away.

[reubster]

Re: Corretto questions

Mal

At first my FC & SC temp readings were around 175 & 190C respectfully.
This was repeatable and therefore useable, but I prefer to see a more "correct" reading of the temperature

My probe is inserted such that it protrudes 10mm into the bowl and can be adjusted in height for different roast sizes.

I tried various methods to "raise" the measured temp:

Moving the probe up or down within the beans varied the temp a little but not as much as I expected [only maybe 5C] .
I generally set it to be about 10mm below the top of the beans.

I also suspected that the part of the probes shaft in the "airgap" between the bowl and the BM was losing heat.
Covering the airgap between the bowl and the rest of the BM lifted the reading, but it made removal of the bowl a little more difficult.

Recently, I modified the wooden block that holds and adjusts the probe such that it is now inserted about 14mm into the bowl [used to be 10mm].
This made all the difference: FC & SC @ 195 & 210ish

amazing what a couple of mm does!

Link below if youre interested

http://coffeesnobs.com.au/YaBB.pl?num=1202170402

[greenman]

Re: Corretto questions

I have mine in lh corner of bucket with a 600g batch it sits just above the halfway mark of bean mass, I think it could go a fraction higher, I drilled the holes when I was doing 400g roasts. I aim hg just off centre in my rectangular bucket.

[GregJW]

Re: Corretto questions

My probe extends 3 cm into the bowl (of my BM 250) but only about 0.5 cm off the bottom (to keep it beneath the paddle). It pokes in on the opposite side (inside) to where I point the HG. I have wrapped the rest of the probe (from 3 cm from the tip back to the plastic - which is a bit melted from previous experimentation in putting it in the bowl ;D :-[) with gaffer tape to insulate it. I think its doing the job.

I am fairly happy with the temp readings Im getting now - 195 FC; 215 SC.

[Thundergod]

Re: Corretto questions

reubster is the DMM attached to the BM?

[JavaB]

Re: Corretto questions

reubster is the DMM attached to the BM?

Good point Thundergod....

You should be aware that Thermocouple equipped temperature meters measure differential temperature between the hot (probe tip) and cold (junction in the meter) points. They have internal compensation to correct for ambient variations.....

But if the meter is placed in a location where it will be heated to a degree above ambient - all bets are off as far as accuracy is concerned....

I position my meter well away from the Corretto where the ambient is stable.... probe tip about 2 cm into the bowl in about the top 1/3 of the bean mass.... and it works beautifully.

[reubster]

Re: Corretto questions



TG
It just used to sit there, because I had, errr, other uses for it.

For CTB, [in case we got big crowds] I used double sided sticky tape to hold it in place.
Its still that way now, and is better caus at the end of each roast, I tip the BM over and give the cavity a blast with the HG to blow out the last of the chaff.
Now the DM stays put rather than falling into the rose bush.....Ouch!

It could be more permanetly mounted by screwing/bolting its cover to the BM.

[bolb]

Re: Corretto questions

Hi all
Thanks for all the valuable feedback, I will do a few roasts this weekend with the probe at different heights and take some measurements for comparison.

Mal

[cjhfield]

Re: Corretto questions

For completeness I would like to add one (small) caution about the Coretto. Bread pans are lined with Teflon which if heated over 250-260 degrees can release a chemical PFOA There is no proven link with this chemical and disease in humans but it is a very long lived compound and so hangs around in the food chain. The compound is toxic to birds and rats. The EPA in the US is taking steps to reduce emissions of PFOA by 95%. There is some weak evidence of a possible prostate cancer link in humans. There is no risk using pans in the normal way but the Coretto and heat gun, while not working at these high temperatures is not that far below them. There may be no risk at all from this compound.

It is hard to put such weak evidence in perspective but I would be happier using a stainless steel bowl and some other method of stirrer.

Chris

[Thundergod]

Re: Corretto questions

Thanks for the reminder Chris but the relevent point is "over 250 degrees".
I hit 233 recently.
Thats measured inside the bean mass.
As the pan heats up from heat coming from the beans I assume it cant be as hot as they are.
And at that point (233 degrees) I cut the heat and cool the beans.

You also said theres no proven link to disease in humans.
Considering how easy it seems to be these days to prove anything dangerous maybe a BM pan is one of the safer things were exposing ourselves to.

Yesterday IIRC there was something about the plastic used to make baby bottles being bad for kids.

[Randy_G.]

Re: Corretto questions

You also said theres no proven link to disease in humans.

Do you trust Dupont with your health? The fumes from teflon when overheated are nearly instantly fatal to birds. That is a proven fact. There are numerous stories about pet birds being killed from someone leaving a teflon-coated pan on a stove without anything in the pan. Doesnt sound like something I want to breathe.

Yesterday IIRC there was something about the plastic used to make baby bottles being bad for kids.

That is actually old news. The BPA (bisphenol A) that is in a lot (nearly all?) soft or flexible plastics has been l9inked to genetic abnormalities and to disruption of hormones . Google "BPA."

The problem is compounded when you look at the cumulative effects of all sources of chemical pollutants in our environment- paints, vinyls, room and air deodorizers, scented laundry detergent, carpeting, lead leaching, additives in personal care products, hormones in foods, etc., etc. Why not try to eliminate what you can when you have a choice?

The bottom line is that it couldnt hurt to eliminate them, but may if you dont.

[ozscott]

Re: Corretto questions

Corretto is big news on this site. I cannot see that its used in the US based on Coffeegeek and similar - shame because its far superior to popcorn maker in both batch size and control. For the teflon you can just remove the circlip and pop out the kneading blade and brush it down with steel wool and do likewise in the tub in the swept area (because beans and chaf can be trapped and brush it off if you dont). If you wanted to be really anal you could spend some time and brush off the entire inside of the bowl...from what I have read so far about hotop and gene cafe etc and for my money I would rather take the time to do that and stick with my Corretto....

[Dimal]

Re: Corretto questions

Yep,

Me too Oz. As a matter of interest when this question was raised shortly after the inception of the Corretto, I measured the surface temperature of the bread pan in my BM and even with the beans at ~230C the highest temperature I could measure on the pan itself was actually less than 200C. This temperature was observed roughly on the opposite wall from the heat gun. It is possible that the bottom of the pan approaches the temperature of the bean mass but I wasnt able to measure this reliably.....

Mal.

[Thundergod]

Re: Corretto questions

As the pan heats up from heat coming from the beans I assume it cant be as hot as they are.

Thanks for that Mal.
Looks like Im a good guesser.