DIY Color Meter

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by jpender »

Brewzologist wrote:Timely post on using roast color meters here: https://artisan-roasterscope.blogspot.c ... color.html

TL;DR - see the two blue boxes at the end of the blog post. e.g. much like using refractometers to measure coffee liquid, it's not as easy as it perhaps seems.
Nice comparison. Color does not fully describe the roast any more than extraction fully describes the coffee balance.

I read that article yesterday. Last year I was thinking about buying the photodetector board that Espresso Vision used (it's about $20) and seeing what I could do with it. But I started to get this sense that it was going to be tricky getting consistent results. And how would I calibrate it? And anyway, how useful is it?

Is it really possible to dial in your grinder based on a color measurement?

Moderator note: Split from Onyx now lists the actual Agtron roast level for visibility.


#2: Post by natew »

Check out

Its a DIY version of the Roast Vision. It uses an agtron-style roast measurement (higher is lighter, lower is darker).
Bizmark wrote:Well this is a bummer: I've been using an Espresso Vision "Roast Vision" unit that analyzes the color of ground coffee, but just checking now the company is closed. That's too bad as their device was only $300

There's also the Tonino device which is probably more precise, but is considerably more expensive at about $750

Searching for "roast color analyzer" brings up other devices but the cost is even more.

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#3: Post by Brewzologist »

********* PLEASE NOTE *********


edited: April 5, 2023

jpender (original poster)

#4: Post by jpender (original poster) »

natew wrote:Check out

Its a DIY version of the Roast Vision. It uses an agtron-style roast measurement (higher is lighter, lower is darker).
Way cool! Thanks for posting this.

EDIT: It looks like it's not fully there. There's a missing 3D file and the assembly instructions aren't that clear. No use instructions at all. Maybe it would be obvious once you started but they could use a few photos at the very least. Well, it is free.


#5: Post by randytsuch replying to jpender »

He had this one pic, but it doesn't help much

There is also a step file, I found an online step file reader, and see this:

My guess is the round hole is for the sensor, and rectangle for OLED.

You need to cut a piece of glass, that must be for the sensor.

He says there is a user guide coming soon, maybe that will clear things up.

Great find, I think this may be in my future.



#6: Post by Milligan »

Maybe someone will take that and do a premade one. The Roast Vision's spiritual successor. Likely some decent demand in that price range seeing how there isn't a lot out there under $600.


#7: Post by DenisSabou »

So take someone else work and make money out of it? This is a private project made possible by the people/community at kaffe-logic discord users. They did all the work, testing, calibration. It should not be posted like this on forums without even asking them for a permission first.

Maybe this topic should be deleted.


#8: Post by randytsuch replying to DenisSabou »

Its published to github under the GNU public license ... in/LICENSE

So its NOT a private project. If that was the intent they should not have published it like this.

And if you read the github page, seems pretty obvious the intent is to share the work.

I wouldn't turn it into a commercial project, but I also feel bad for those who don't have the ability to build something like this.
There are no inexpensive options out there.


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#9: Post by drgary »

I'm looking forward to seeing the manual. It's about time there was something open source like this that hobbyists can assemble. It also seems obvious by the way it's posted that it's meant to be publicly shared.

What I WOULD do for a good cup of coffee!

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#10: Post by jpender (original poster) »

Step files. I found an online app to display them and then discovered that the MacOS Finder and Preview apps do it natively.

So what I noticed was missing, and it's not a huge deal, is the step file for the lid that doesn't have a hole for the switch. If I were to make one I'd drive it externally with a USB cable connected to a little 5V supply, those white Apple cube things that I have a bunch of. That would be the easiest. So then the switch hole is unneeded. If I knew how to manipulate those files I could get rid of the hole. Or I could just cover it with something. I dunno, duct tape?

I'm so tempted to try and make one just because it looks like fun. I was almost going to buy the Sparkfun photodetector board last year and try to figure it out myself. But now it's almost (hopefully) a paint-by-numbers kit.

But... when I told my wife about it she asked, "Do you need to know the color of your coffee?"

No. Not really.

It would just be fun.