First crack temperature reading too high...

#1: Post by **BartG** » March 31st, 2017, 1:14 pm

I've got a bit of a strange phenomenon on my Quest with Phidget 1048 temp sensor.
Normally for a certain bean I would reach first crack at around 194°C every time and suddenly the last three roasts 1C is at 204°C...
Same goes for other beans: the 1C crack temp reading is higher and above 200°C.

Strange and I tried several things (grounding the phidget, getting it out of its box) but nothing helps.
Anyone familiar with this phenomenon?

Thanks,
Bart

#2: Post by **Devin H** » March 31st, 2017, 2:18 pm

A few questions.

1. Have you 'updated' Artisan? Maybe you lost your offset? or it got adjusted?
2. is your roasting ambient temp changing? In other words, my 1C points seem to change as the seasons change (I roast in the garage)
3. Have gremlins entered your TC/probes? I don't know how to fix this problem btw...

March 31st, 2017, 4:14 pm

OK, good suggestions (apart from the gremlins

).

No, i didn't change artisan... or, well, I did alter the curve settings for the ROR.
This is under Tools>Extras>Graph
But this shouldn't alter the temp readout, no?

I've added an MET probe, but still got one normal 1C with the new probe in place.

Temp in the cellar where I roast changed to maybe 3-5°C higher, could this have such a huge impact?

The Quest itself is getting rather noisy and I plan on disassembling it for a deep clean, but shouldn't affect the temp...?

Thanks for thinking along!

#4: Post by **adondo1** » April 26th, 2017, 10:01 am

Did you find any solution to this? I have the same issue right now actually. 1st crack happens at around 205-207 C instead of 198-199 as before.

April 28th, 2017, 2:11 am

No, unfortunately I didn't find a solution.
I thought for a while that the change in temp of the place where I roast might be the cause. But this can't be it: hotter room temp would only speed up the roast proces slightly.
I guess it must be caused by the way the bt probe is inserted (unlikely), or a calibration issue with the phigdets electronics.

Since the higher first crack readings are constant, I've now adapted to them and stop the roast on new reference temp (+/- 5°C higher)

#6: Post by **AssafL** » April 28th, 2017, 2:28 am

Could be grounding issues. I've seen jumps of 5C (and more) if grounding wasn't right (e.g. floating).

#7: Post by **Devin H** » April 28th, 2017, 10:09 am

Since the higher first crack readings are constant, I've now adapted to them and stop the roast on new reference temp (+/- 5°C higher)

You've got it. While I'm not sure about why the temp readings changed, if it's constant, then you once again have a useable/reliable data point going forward.

Happy roasting

#8: Post by **mikekarcic** » April 28th, 2017, 11:07 am

Interesting. Any difference in the quality of the roast?

April 29th, 2017, 3:45 am

AssafL wrote:Could be grounding issues. I've seen jumps of 5C (and more) if grounding wasn't right (e.g. floating).

How would I proceed to ground the unit? I've now put a wire on the aluminium encasing of the phidgets and connected that wire to a metal gas pipe.
But that doesn't change anything.

April 29th, 2017, 3:49 am

mikekarcic wrote:Interesting. Any difference in the quality of the roast?

No, luckily there isn't a change in quality.