# Thermocouple in bean mass worth it?



## TomHughes (Dec 16, 2019)

This is a question a bit towards those who put a thermocouple in their gene I think I found a thread where you did @Rob1?

Im rebuilding my DIY roster and considering trying to get a thermocouple into the bean mass, it's not all that easy as the rotisserie drum spins so the it needs to be position so it doesn't coil.

Was knowing bean mass temp worth it? What kind of thermocouple would be best for the job? They seem to go on eBay pretty cheap for less than £10 but I don't want to buy junk!


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## Batian (Oct 23, 2017)

@Hasi may also be able to help out with this. Apart from the job of fitting the thing in a drum if it has not been designed for it, the speed that the thermocouple can send the reading to your recording/viewing device becomes relevant. Faster thermocouples are more expensive.

If it can be done, knowing the bean mass temp is definitely better than relying on exhaust temperature. I suppose the question becomes how far do you go with adaptions before it is better to buy/make a purpose built machine?


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## filthynines (May 2, 2016)

I looked into doing it on my Gene, on both the small and big one. Came to conclusion that it would need to rotate on the drum and so the reader would need to be wireless. I gave up and bought a Dalian. That's making my head hurt too, but at least there are existing probes to be swapped in and out.


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## TomHughes (Dec 16, 2019)

Batian said:


> @Hasi may also be able to help out with this. Apart from the job of fitting the thing in a drum if it has not been designed for it, the speed that the thermocouple can send the reading to your recording/viewing device becomes relevant. Faster thermocouples are more expensive.
> 
> If it can be done, knowing the bean mass temp is definitely better than relying on exhaust temperature. I suppose the question becomes how far do you go with adaptions before it is better to buy/make a purpose built machine?


 Thanks, 
Currently I don't use temp much at all, just visual, sound and time. I have roasted the same beans over and over so I know them pretty well now. 
The drum will now be encased, so visual is not possible so wondering if temp would improve things. 
There is a way of getting the thermocouple in and sitting the LCD on the rotating bit, which would rotate too but I can pause it briefly to read.

I won't be buying anything fancy as I relish the challenge of trying to build it, so far it's cost be around £30 and I've found that mostly good results for my palate compared to what I've had from most roasters. 
In my mind coffee roasters are ridiculously over priced considering what they really are, just a heat source, a way of agitating the beans and a temp sensor. How they cost thousands is beyond me.


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## Rob1 (Apr 9, 2015)

In my signature there's a link to my thread with everything I used and the coding. The thermocouple is just wire....it isn't accurate or inaccurate, or fast or slow, so long as it's made properly. Avoid ones with a steel sheath around the tip as they are naturally slow to respond...unless they've done some magic with them and they somehow aren't. Magic might explain an expense.

The amplifier, wiring, connections, calibration and coding plays a huge part in accuracy.

Yes it was worth it.


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## Rob1 (Apr 9, 2015)

Oh you know what actually I should have said K type thermocouple....


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## Lovic (Apr 10, 2019)

Anybody tried the temperature sensor like the Gene Café CBR 1200 ?






We can really see it on the drum... Nothing special in my opinion and it could be done very easily I guess with this type of part:










Any thoughts ?


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## Rob1 (Apr 9, 2015)

No that wouldn't be very good. Even if it's technically possible to install it (you'd have to bore a large hole and get a bolt on it to hold it in place and remove enough surrounding plastic to seat the dial) in a place where you can actually see it at least momentarily during a rotation. The gene readout does give you a fairly good indication of air temp in the drum and this wouldn't really improve that. You could use a variation of my setup with a small hole for a thermocouple and a slim digital display connected to an arduino on the handle of the drum giving you a temp readout actually on the roaster rather than in external software.


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## TomHughes (Dec 16, 2019)

Rob1 said:


> Oh you know what actually I should have said K type thermocouple....


 Ok, so a K type thermocouple. 
I have had a look as some look like the cord is nylon? 
For instance something like this.

https://www.ebay.co.uk/itm/DUAL-TWO-CHANNEL-2-K-TYPE-DIGITAL-THERMOMETER-THERMOCOUPLE-SENSOR-1300-C/323942435383?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3Df59d967b82ac499e836148663a6cf2b7%26pid%3D100675%26rk%3D1%26rkt%3D15%26mehot%3Dnone%26sd%3D264677028732%26itm%3D323942435383%26pmt%3D0%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3Aaa70792e-953e-11ea-9044-ca42625bcd64|parentrq%3A0f1161461720a0f2bc3b33d0fff13078|iid%3A1

Essentially I just want 1 or 2 cheapish thermocouples giving me a screen readout. I am not bothered about connecting it up and collecting the data on it.


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## Rob1 (Apr 9, 2015)

Well you might be able to clamp that unit onto your drum. It might be effected by the heat, I don't know...you'll have to check the temp around your drum and see if it falls within recommended operating temp for the unit. The insulation might be nylon, but on mine it's fibreglass.


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## TomHughes (Dec 16, 2019)

Rob1 said:


> Well you might be able to clamp that unit onto your drum. It might be effected by the heat, I don't know...you'll have to check the temp around your drum and see if it falls within recommended operating temp for the unit. The insulation might be nylon, but on mine it's fibreglass.


 Cool thanks. 
The temp where that wire is will get to about 150deg C. So it needs to be pretty heat resistant! 
Would a fibreglass one be ok?


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## Rob1 (Apr 9, 2015)

I think so, there should be a spec sheet. I meant the heat could affect the electronic reader it connects to not so much the wire. The reader is going to need attaching to the drum.


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## TomHughes (Dec 16, 2019)

Rob1 said:


> I think so, there should be a spec sheet. I meant the heat could affect the electronic reader it connects to not so much the wire. The reader is going to need attaching to the drum.


 Ah right. No the reader will be about 2-3 inches out from the drum at least, so shouldn't get too hot.


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