Roast-Pi

[cedar]

neat project! thanks for the post. I'm currently attempting to build something similar. I have no coding experience so I am attempting to read through your code and modify it to work for me. I'll update you if I get it working, and of course give credit where credit is due.

EDIT: Sorry for the double post. Not sure what happened and for some reason I can't delete the first post.

[cedar]

Just a note to advise that the Roast-Pi has completed its 166th roast.

I've changed my usual profile to a "step", where the target is a slightly-inclined ramp to the final temp. It means that the heat gun goes flat out until it gets close to the ramp, and then the auto controls cut in and taper the rate of rise. Looks like this:



For the Sulawesi Blue I'm using, I adjust the final temp/time to just get to second crack. It gets a very repeatable result.

Gonzo

Really great project! I'm working on something similar using a popcorn popper. Would you be willing to share your code? Thanks!

[gonzob]

Just a note to advise that the Roast-Pi has completed its 166th roast.

I've changed my usual profile to a "step", where the target is a slightly-inclined ramp to the final temp. It means that the heat gun goes flat out until it gets close to the ramp, and then the auto controls cut in and taper the rate of rise. Looks like this:



For the Sulawesi Blue I'm using, I adjust the final temp/time to just get to second crack. It gets a very repeatable result.

Gonzo

[Dimal]

Nice job Gonzo...

Mal.

[gonzob]

Hi all.

While the Roast-Pi is doing its 77th roast, I thought I'd update the forum. I've added a few configuration options to the display - last week's roast looked like this:



It gives me the ability to change the peak temp and roast time, and the target profile simply scales itself accordingly.

Gonzo

[davidm870]

Hey, Gonzo

Amazing how this whole Internet thing works, isn't it? We're grateful for the inspiration and as we get the bits working we'll let you know how it goes. Our funding campaign has a few hours left to run at https://www.indiegogo.com/projects/t...res-de-ometepe and if you have a bit of spare change we'd appreciate it; even more so if you share our story with your friends. There's a photo of our roaster, made in Guatemala in the 00s on our Indiegogo site in the gallery.

[gonzob]

Wow. Chuffed!

Gonzo

[gazza]

Links to CoffeeSnobs pop up where you least expect.

Community, coffee and classrooms in Nicaragua | Raspberry Pi

Good one Gonzo.


Gary

[gonzob]

Plenty of space on the screen to show ROR and a nice graph.


Gary

True, but my graphs are boringly predictable. I specify the ROR via the profile file, and the auto control follows it. They all look the same! I can look at them using the Pi's web interface, but I'm using that less and less these days.

The reason for the screen was because I needed to know when FC and 2C were coming, and just as a check that the actual and target temps were not too dissimilar.

Gonzo

[gazza]

Plenty of space on the screen to show ROR and a nice graph.


Gary

[gonzob]

The Roast-Pi has just become more visible. See attached photo.

I now have a small display running off the composite video port on the Pi. It gives me Elapsed time, Currnt temp, Target temp, Power % (i.e.PWM). For those of you that think the display bears more than a passing resemblance to a rear-vision miror mounted reversing screen, you are right!

Note also the large hood to the left of the roaster. That sits on top of my bean cooler exhaust fan and drags the hot air and chaff from the top of the roaster. It sucks through a big kitchen sieve (under the hood) so the chaff is trapped. I remove it when the roast is over and I want to cool the beans.

Gonzo

[artman]

That's awesome, looks like your setup replicates the temps very accurately.

Cheers

[DesigningByCoffee]

The plans I have are:

1. longer "plateau" in the middle
2. no plateau, but keeping the overall time (slower ramp)
3. as fast as possible to 200 then creep to 220

My tasting skills are not too developed, so I can't guarantee I'll be able to discern differences from the trials, but we'll see....

Gonzo

Hi Gonzo
Certainly reckon you will taste the difference, now that you can control the roasts so accurately
Just use the same greens, run your three trial and we'll be interested to hear your findings! I went through this process myself over a number of months - very interesting process!
Cheers Matt

[gonzob]

Looking real good Gonzo, glad its working for you.

My 300-700 gram roasts work very well with fairly accurate and repeatable results on my rig.
Lately I have been pushing bigger batches, 840 grams is the largest so far and find that at those sizes there is not enough heat output to keep up with the ramp up to 1C.
I'm going to try an additional heat gun on the next roast to see what happens.

Looking forward to hear your tasting report

Thanks guys.

Yes, fg, I have run larger batches (510g), but the power graph makes it readily apparent when the heat output is insufficient for the desired ramp. For example, see the graph above, where it hits 100%. I'm now limiting myself to 300g, and then planning to do what Mal says. 300g is a nice size for me - almost a week's consumption.

The plans I have are:

1. longer "plateau" in the middle
2. no plateau, but keeping the overall time (slower ramp)
3. as fast as possible to 200 then creep to 220

My tasting skills are not too developed, so I can't guarantee I'll be able to discern differences from the trials, but we'll see....

Gonzo

[fg1972]

Looking real good Gonzo, glad its working for you.

My 300-700 gram roasts work very well with fairly accurate and repeatable results on my rig.
Lately I have been pushing bigger batches, 840 grams is the largest so far and find that at those sizes there is not enough heat output to keep up with the ramp up to 1C.
I'm going to try an additional heat gun on the next roast to see what happens.

Looking forward to hear your tasting report