When you make a grind adjustment, you expect an immediate result. This makes sense because grind has a serious effect on the flavor of your coffee. So what does it mean if you make an adjustment, but don’t see a change in how your coffee extracts?
Sometimes, it means that a part is damaged in your grinder (although we do our best to build great machines, no grinder is invincible) but more often than not, our support team encounters customers who are missing an important step in the dial-in process: purging after a grind adjustment.
Sometimes it is done when changing between coffees, but in this case, we do it when changing through grind settings. To understand why it’s important, we’ll want to take a brief journey into a burr grinder:
On our Encore model, two steel burrs grind up coffee beans, which fall to the bottom of the grind chamber. From there, a set of four paddles (aptly named the “paddle wheel”) push that ground coffee around the base of the burr set and out through the discharge chute.
Coffee travels through the chute horizontally about a half-inch before making a 90-degree turn down, where it falls into the grounds bin. This distance and corner are designed to help combat static buildup in ground coffee, which is great for reducing mess, but does result in some retention of ground coffee.
Most burr grinders will retain some partially ground coffee between the burrs as well as some coffee which has already been ground by the burr set, but which hasn’t physically moved all the way through the grinder’s discharge chute. Depending on your roast, grind size, and model of grinder, you can expect there to be several grams of retained coffee in the machine. This is coffee that we want to purge from the grinder in order to see clear, distinct changes during extraction.
Not purging means some coffee which was ground at the previous setting is still in the machine. The user makes an adjustment and grinds another dose, which pushes that old coffee through the discharge chute, resulting in limited or no observed change in extraction.
Purging a little bit of coffee after a grind change removes these leftover grounds and will drastically improve your impression of adjustability.
After you’ve made that change, it’s best to continue grinding for another few seconds to purge the coffee from the previous size and transition period.
Most of our grinders require only a few grams of coffee ground through to purge what is remaining from the previous grind, meaning a few seconds of grinding.
On the Sette family of grinders, the innovative design of the burrset – wherein the ring burr rotates around the cone burr – results in very little retention: about 1 gram of coffee which requires less than a second to purge! If you’re curious about the mechanics of this, you can read more here: https://www.baratza.com/sette-part-ii/
We also recommend, when using a Baratza grinder, that you grind coffee through the machine while adjusting your grind.
Let’s go back inside that machine again to better understand why we do this.
Grind size is regulated by the distance between each burr. If you’ve got an empty machine, these burrs can move closer or farther apart unobstructed. When coffee is in the system (especially partially ground coffee retained between the burrs), moving the burrs closer together will press down on that ground coffee. This creates resistance against the burrs which transfers to the adjustment system. The result of this kind of use is a shorter lifespan of the adjustment assembly, leading to more frequent repairs.
Although repairing our machines is quite simple and encouraged, there is no need to put in the work if you can avoid damage entirely by purging coffee through the system during an adjustment.
Certainly, we all hate to waste coffee, but in the case of purging, a little unused coffee between brews can get you faster to your delicious cup of coffee, while also keeping your grinder in better shape for a long time.