Yes! We dial in our brewer here at Cut HQ using an EK-43 and refractometer. Alas, the number we use on our ek-43 is not necessarily transferable because not all burrs are ‘zeroed’ (they are not aligned to the same number during manufacturing or maintenance). It produces a home-oven effect in which the number becomes specific to the machine and explains why muffins burn or coffee over-extracts despite recipes. Down the line, I would like to team up with local hero Calum (of Save Us Service fame) to zero account grinders and enable us to pass along our parameters. BUT in the meantime, let’s talk dialing in by taste.
Matt Perger made this amazing coffee compass for filter. It is simple: brew a cup, locate your position, and use the compass to reach the center. Tastes harsh? Extract less with a courser grind and less coffee. Nuts and vegetables? Extract more with a finer grind and more coffee. Great right? It is like he is a World Champion coffee brewer or something.
The question becomes, where to start: Time? Dose? Grind? It’s clear that the compass is designed to function with a whole spectrum of roast philosophies. Lower development during roasting means less extraction in the cup. So a really underdeveloped coffee requires a higher dose and/or long extraction time. Perger is clearly (and generously) making allowances for such roasting errors.
I approach all of our coffees with one goal: roast for proper development to create a sweet, juicy, and clean cup that highlights the origin’s terroir. Hence, we can eliminate dosage from the compass and use the golden ratio of 1:16.5 (one gram of grounds for 16.5 grams of water). The math becomes quite easy when you brew a pot (without coffee) and weigh the water. Then divide that number by 16.5 and you have dosage!
So, brew the 1:16.5 ratio and grab your compass. Anything under-extracted will taste savory or sour (key hints are the flavours of raw nuts, IPA hops, fruit peel or citrus zest). Often it will also just taste weak or tea-like. Solution: grind finer. Alternatively, anything over-extracted will taste very sharp and severe (key identifiers would be notes of spices like cloves, the astringency of vermouth or tannins, and the bitter char of smoke or ash). It will be harsh. Solution: grind courser.
A well-extracted coffee will taste sweet. It will have a complex and pleasant acidity that is balanced to the other notes. It will be juicy and creamy with a smooth mouthfeel and have a very long finish. If you use the compass and end up lost, blame the roast. Without proper development you will have savory flavours like spicy clove, or tangy tomato, or grainy bread. Even when the roast is close, you end up with Baker’s chocolate or citrus peel rather than a delicious dessert or ripe fruit.
tl;dr: use a 16.5 to 1 ratio and adjust the grinder until you hit the literal and figurative sweet spot.