FreshRoast SR800, Phidgets, and Artisan - Page 2

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
travis_rh
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#11: Post by travis_rh »

MNate wrote:BT is as close as you can get to having a probe in the middle of the bean mass. But the ET... environmental temp's use is less clear than on the drum roasters. What would you do with the info of air temp at the top of the chamber or underneath the chamber, if you wanted to call either of those ET? I can't find how it is going to change my technique at this early stage in my roasting. Therefore just one probe in the bean mass is probably enough for me.
The "ET" value in my setup is basically worthless unless you want to get into thermodynamics and calculating energy balances. It could provide a more qualitative than quantitative indication of rate of rise, since you're indirectly measuring the heat absorbed by the beans.
gullygossner wrote:I ordered some thermocouples from phidgets today and am most likely going to mimic your setup. Looking at your graphs, your ET is lower than your BT, can you explain why this is? Are you measuring an environmental temperature above the bean mass so some of the heat is being drawn out from the roast at that point?

In regards to your ror oscillations, I don't think there is any way around that with the way that the fan speeds are stepped, it would have been nice if the fan control were smoother but I suppose for the price of the unit concessions must be made. I have been toying with the idea of putting the heater on an ssr and controlling the fan via my TC4+ board but I am a little hesitant to start modding as I purchased this unit in the name of simplifying my experience coming from a few different home made roasters.
Yeah, my ET probe is located above the bean mass. Essentially, it's measuring the temperature of the air as it exits the roaster.

gullygossner

#12: Post by gullygossner »

Thank you for the reply! I got my thermocouples and will be giving it a go in the next few days. My plan is to try to place the et probe as far down in the center of the "fountain" portion of the bean mass as possible, I don't hold out a ton of hope for overly useful et measurements but we shall see.

travis_rh
Supporter

#13: Post by travis_rh » replying to gullygossner »

Understandable. Keep us posted all the same though.

My original thinking was that I knew the temperature of the air going in, so knowing the temperature of the air going out gives you some sense of how much or how quickly the beans are absorbing heat. In actual use, though, ET provides no value for me.

gullygossner

#14: Post by gullygossner »

I did three roasts tonight with the thermocouples installed. Nice to have the information for repeatability but I don't think the ET Values are going to be super useful. The ROR rollercoaster is similar with the fan steps. I think I may try to draw out the drying phase a little bit longer maybe by starting at heat 2 rather than 3 next time, but we'll see how it tastes.


travis_rh
Supporter

#15: Post by travis_rh »

gullygossner wrote:I did three roasts tonight with the thermocouples installed. Nice to have the information for repeatability but I don't think the ET Values are going to be super useful.
Yep, that's exactly how I feel. I'd be curious to know if anyone's really using it for anything of value.
gullygossner wrote:The ROR rollercoaster is similar with the fan steps. I think I may try to draw out the drying phase a little bit longer maybe by starting at heat 2 rather than 3 next time, but we'll see how it tastes.

image
Looks about as good as it can given the nature of the beast. I've had, maybe, one or two roasts out of a few dozen now that had a truly smoothly declining RoR. Couldn't tell ya what I did differently, though...

Iowa_Boy

#16: Post by Iowa_Boy »

I have been thinking of adding Phidgets to my SR800, but still just learning how to use the roaster.
Seems like getting a smooth declining ROR is pretty difficult anyway given there isn't infinite control of fan and power.
Ultimately, even with the Artisan data, that seems to be a limiting step.
I am just brainstorming here, but could some sort of Variable Transformer work to better control the ROR?
Ideally, if you could smoothly reduce the fan/heat over time (with more than 9 options), you would have better control over ROR.
Not sure the result would be worth it, but just a thought!

gullygossner

#17: Post by gullygossner » replying to Iowa_Boy »

One would have to separate the heater power and fan power, adding (I'm guessing here) a ~20V DC power source to control the fan seperatley as I suspect the unit uses the smaller heating coil in conjunction with a bridge diode to spin the DC motor on the fan. Getting into pretty hacky territory. Worth it, maybe?