Coffee Data Science

How to Destroy an Espresso Machine

A picture story of an unexpected experimental failure.

5 min readDec 20, 2024

I have been investigating water input on espresso machines, and I have been generally disappointed by most water diffusers. This has led me to modifying my own and having a custom shower screen made for my manual machines.

Enter Sworks! Sworks came out with a precision shower screen, and I bought it to experiment.

However, I found a similar issue in that water came out from the sides a little faster than the middle, which is probably due more from how water enters the diffuser than the actual shower/diffuser.

So I made some silicone rings similar to what I had in my previous shower screen.

They were relatively easy to make an insert.

Metrics of Performance

I used two sets of metrics for evaluating the differences between techniques: Final Score and Coffee Extraction.

Final score is the average of a scorecard of 7 metrics (Sharp, Rich, Syrup, Sweet, Sour, Bitter, and Aftertaste). These scores were subjective, of course, but they were calibrated to my tastes and helped me improve my shots. There is some variation in the scores. My aim was to be consistent for each metric, but some times the granularity was difficult.

Total Dissolved Solids (TDS) is measured using a refractometer, and this number combined with the output weight of the shot and the input weight of the coffee is used to determine the percentage of coffee extracted into the cup, called Extraction Yield (EY).

Initial Tests

In my initial testing for TDS/EY showed an improvement over the original for a few shots, so I was going to test this for a few days, and then I wanted to compare to the previous shower screen.

Taste seemed to trend with TDS/EY, but there was noise in the signal, so I wouldn’t say these results are definitive. However, trouble was brewing.

Trouble

When I tried to unscrew the shower screen, it wouldn’t budge. The screw to take it off the custom diffuser is behind the shower screen, so you can’t even take off the shower screen if it can’t unscrew the shower screen piece.

I left it for awhile because I didn’t want to break my machine. I tried a variety of things to get the silicone rings moving. I realized they were stuck and wouldn’t allow the shower screen to move at all. I later found them to be so fused with the plastic diffuser that I had to destroy it to get the shower screen off.

This is olive oil to try to get some lubrication. That didn’t work, but around that time, the screw became a little loose.

So I tried for 30 minutes to jiggle it, and I was able to loosen the screw enough to remove the whole thing without damaging my machine.

Destroying a Diffuser

I had to destroy the diffuser to remove the shower screen. I figured that would be cheaper to replace the plastic diffuser than the entire part.

I ended up using a power drill, and I spent 30 minutes drilling multiple holes.

Piece by piece, I finally got the thing off with minor damage to the shower screen.

I also had a mess to clean up.

A pile of plastic shavings at the end.

I bought a new plastic diffuser, and I will test again. I will probably use a silicone ring in the basket instead of the shower screen. Luckily, my machine was not damaged as a result.

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