Different Beans, Same Grind Settings, different volume


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Aug 3, 2023
Montreal, Canada
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Hi, I'm new into the world of have a grinder at home.
I have a Breville smart grinder pro. I had two different bags of beans.
One more Light Roast, other medium-dark.
I noticed that they produce different volume of coffee after grind. Per example: Lighter roast my basked fits 18g, the medium-dark fit's 17g.
There is a science, explanation for it?
I weigh the whole beans before dropping them into the grinder. That is the number I use for the coffee water ratio. Always consistent, always right.

When I use dark roast beans I use a finer grind, I use slightly more coffee (per water) and a slightly coarser grind. There are reasons for this, explained better than I ever could here:

I am not familiar with the Breville smart grinder pro, but I do know many grinders have presets for different kinds of coffee drinks and different kinds of bean roasts etc., that adjust the grind and in some cases the dosage (per consistent measure of water). I like to avoid all "automatic" compensations the machine may provide, so as to take full credit for screwing it up myself.

So I would figure out a medium medium medium setting on the machine, and adjust the ratio of coffee to water, (measuring weight of whole beans) and the grind setting you like overall, for a medium or light-medium roast coffee. Then for a dark roast I would add a bit more coffee and grind it a bit coarser.

Confession - I used to think this XXXX didn't matter. But wow it does make a difference. Especially in a pour over. I haven't jumped into the espresso world yet. I am quite intimidated by it. But for pour over, I kind of have this figured out, and am able to perform it consistently. I am not ready to stray far from home.
Intimidated by espresso? Come on now, what brew method can leave you scratching your head at times, making daily changes for bean age, humidity/temperature, grind fineness to the micron, dose weight within .2 grams +/- and then change coffee to repeat, repeat, repeat?!? I will gladly say espresso is never mastered as many variables change constantly, but once dialed in and repeated it's insanely rewarding that few other things in life can match for me.

I would say I push the boundaries for my use as I home roast and sometimes use up to 3 different coffees daily and dialing each extraction in with hand grinding the majority of the time. That has it's own variables such as grind fineness, rpm and angle of feed rate... never gets boring though!
You know, it strikes me now that perhaps I was responding to the wrong issue in the original post.

I have noticed this too. The important thing is that volume measurements are always squirrely. The fineness of the grind will affect the volume. The density of the packing will affect the volume, blurry pre-caffeinated morning eyeballs will see volume differently. I stick with weight measurements. 30 grams of beans will grind to 30 grams of coffee grounds, regardless of the size of the beans, regardless of the country of origin, regardless of the roast, regardless of the grind, regardless of the tamping. So in my ratios and all, I measure and go by weight not volume. Hope that helps.
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