Scale Accuracy Issues

About six months ago, I picked up a cheap 0.01 g scale from Amazon. These go by a few names, but if your scale looks like this, then it’s probably the same scale: Over time, I’ve noticed something odd about the measurements I get from the scale. I usually weigh 18 g of beans for… Continue reading Scale Accuracy Issues

Modeling Extraction

In the academic literature, several models have been proposed for extraction of soluble components from solid coffee. Some of these models are very detailed. Some use computational fluid dynamics (CFD) to model fluid flow through the packed bed in three dimensions. One of my favourite models was described by Moroney et al. in their 2019… Continue reading Modeling Extraction

The Brewing Control Chart

I’ve watched a lot of YouTube videos on dialing in espresso. Most of them follow the same basic approach: You choose your dose based on the portafilter basket you’re using, then you adjust your grind setting so that you’re hitting a brew ratio of 1:2 in 25 to 30 seconds. For me, it always felt… Continue reading The Brewing Control Chart

An Improved Model of Grinding

Our previous model assumed uniformly sized particles of ground coffee. However, real coffee grounds usually have a bimodal size distribution which looks something like this: The size of the larger particles, often called “boulders”, is controlled by our grind setting. But there is also a peak on the left, corresponding with smaller particles called “fines”.… Continue reading An Improved Model of Grinding

A Simple Model of Grinding

When I think of what a grinder does to coffee beans, the simplest idea that comes to mind is that it breaks the beans into uniform chunks whose size is determined by the grinder setting. This process is illustrated below. When the ground coffee is put into a portafilter basket and tamped, it forms a… Continue reading A Simple Model of Grinding

Measuring Density

Let’s kick things off with something I’ve been exploring recently. I had noticed that dark roasts take up a lot more space in the basket than light roasts, and thought I would try to measure the density of the beans to see how it correlated with the type of roast, where the beans came from,… Continue reading Measuring Density