New method to measure grinder fines percentage? - Page 7

Grinders are one of the keys to exceptional espresso. Discuss them here.
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cafeIKE
Posts: 4704
Joined: 18 years ago

#61: Post by cafeIKE »

About 15 years ago, I bought a Mich. Sci. F50 load cell to cobble up a 'tamper' so I could repeat tamp pressure regardless of depth. I was going to modify to an IDC crimp stand.

Basket support machined...
Ennui intervened...




Stand likely needs a little TLC clean & lube
OP PM if you'd like the bits.
Full docs included.

jpender
Posts: 3863
Joined: 11 years ago

#62: Post by jpender »

crwper wrote:I used doses of 15.5 g, 14.5 g, 13.5 g, and 12.5 g to avoid the places I know my scale isn't accurate.
I bought a milligram scale that did the same sort of b.s: it preferentially reported whole number readings when it "sniffed" them nearby. I returned it and stuck with my older milligram scale that does not lie brazenly. I even took the time to write a review but it disappeared a short time later. Oh well, caveat emptor on the amazon marketplace.

I can recommend the 500 x .01g scale I have been using for about 10 years. It's very reliable, precise to .02g (as advertised), fits my Robot, and travels well (I've dropped it numerous times with no consequences). You used to be able to get them for under $20 on amazon but for some reason they no longer sell them. The manufacturer offers them for $28 (free shipping). Seems a little steep nowadays but it is a good scale. They also limited the .01g range to just the first 100g above the tare; from 100-500g it displays 0.1g resolution. For coffee purposes it doesn't matter but I wonder why they did that. I bought one of the newer ones for a now abandoned project and it works just as well as the first one, even without the extra mystery screw that I didn't use when I put it back together.

https://awscales.com/scalemate-500g-x-0-01g/

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K7
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#63: Post by K7 »

crwper wrote:A couple of weeks ago, I finally made the time to repeat the previous puck density experiment, with a few improvements:
...
Off topic, but I also saw your blog post on extraction modeling which I find most interesting:

https://quantitativecafe.com/2021/11/14 ... extraction

I was actually looking into formulating a similar mathematical model myself when I stumbled on your blog. :) Mainly to quantify the effect of puck thickness... I look forward to your updated model for a more typical espresso shot if you get to it at some point.

crwper (original poster)
Posts: 131
Joined: 3 years ago

#64: Post by crwper (original poster) »

Thanks! I will definitely keep this in mind if I decide to replace the scale.

The other option is to do a brain transplant on this one. Someone mentioned to me that the load cells in these is usually just fine, and it's only the firmware that's an issue. So I'm thinking of opening up the scale and putting a custom board with BLE module in there. :-) If I get it up and running, I'll open source everything, so maybe someone else can do the same.

crwper (original poster)
Posts: 131
Joined: 3 years ago

#65: Post by crwper (original poster) »

K7 wrote:I was actually looking into formulating a similar mathematical model myself when I stumbled on your blog. :) Mainly to quantify the effect of puck thickness... I look forward to your updated model for a more typical espresso shot if you get to it at some point.
For the past month or so I've been splitting my espresso shots in the morning and measuring TDS and mass for the split shot. The plan is to fit the data using the model in order to infer parameters for a more typical shot. It's looking really promising so far, with a few pairs of curves where I've changed one variable, e.g., grind setting, OPV pressure, paper filter under the shot. I think there's going to be a lot to learn here. Should be posting on this in a couple of weeks.

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cafeIKE
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#66: Post by cafeIKE »

Got one of these




AccuWeight Digital Gram Scale

It repeats ±0.01g over the short term and ±.02g over a longer interval.

GDM528
Posts: 837
Joined: 2 years ago

#67: Post by GDM528 »

cafeIKE wrote:About 15 years ago, I bought a Mich. Sci. F50 load cell to cobble up a 'tamper' so I could repeat tamp pressure regardless of depth. I was going to modify to an IDC crimp stand.

Basket support machined...
Ennui intervened...

image


Stand likely needs a little TLC clean & lube
OP PM if you'd like the bits.
Full docs included.
Vacuum tubes! Vacuum tubes! Are those 6L6's at the far-right? About time they get involved in the art and science of espresso-making.

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cafeIKE
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#68: Post by cafeIKE replying to GDM528 »

No, they're either 12AU7 or 5963. The board is the driver for an M-125. See teaching the Tubes4HiFi / VTA M-125 to sing. It's long and boring unless you are a tube amp aficionado prone to risking electrocution.

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