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Comment by mafuyu | Hacker News Reader

Seriously? The grinder is the most important part, in my experience. When I first got into aeropress and pourovers, I was frustrated for years with bland and inconsistent brews. It was only after I upgraded to a decent burr grinder that everything fell into place. It’s just impossible to tweak anything else without first starting with a good grinder. I make adjustments of a few micron at a time with my grinder, and the difference is significant for both espresso and pour over. It’s much rarer that I make adjustments in water salts, brew temp, and brew method.

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Quality of beans and water in some order, followed by temperature and time, then grinder.

Grab some 6 month old beans and brew them with metallic water at 85c, no grinder in the world will make that palatable.

> adjustments of a few micron at a time

Lol, no you don’t. Microns are much smaller than you think.

>Lol, no you don’t. Microns are much smaller than you think.

You absolutely do.

Many stepped grinders will have steps on the order of magnitude of 5 microns, EG-1 being probably the easiest one of the bunch to prove [1].

But note that this is talking about the difference in the _burr distance_, not the ground particle size difference.

In a world where we figured out how to make perfect burrs that produce uniform particle sizes these _might_ be the same, but even the most expensive and fanciest coffee grinders produce a relatively wide distribution of particle sizes.

[1]: https://weberworkshops.com/products/eg-1

Speaking as a someone who does DIY CNC, it's easy to add an adjustment dial labelled in 5 micron steps. But those labels are basically decorative if other imprecision in the machine means adjustments aren't reliably reflected in the output.

Even if your coffee grinder is in a room temperature-controlled to within 1 degree, the heat output of the motor could easily cause more than 5 microns of thermal expansion.

But obviously, if the coffee tastes good to you, then that's a coffee making success regardless of how precisely you're grinding things.

While I agree in general, a good quality burr grinder is surprisingly consistent. I'm not sure you could reliably get distinct results one notch apart, but at a given notch you will have a very narrow spread in grain sizes and a couple notches apart they will be visually distinct. James Hoffman has some videos comparing several cheap and expensive grinders, including looking closely at the grain size, and you can see the difference clearly.

Surprisingly consistent when measured using coffee that is ground to hundreds of microns is not an indicator about consistency at the few microns level. Use high quality calipers on the burrs, you’ll be shocked how much variance you see run to run at one adjustment, never mind what happens when you move the dial. Micron marks on grinders are pure marketing.

I'm more than willing to admit this being true on like... 98% of grinders out there; would be a little surprised to see that in a insanely expensive and _very_ overbuilt grinder like EG-1.

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