In an effort to rationalise my coffee setup I did a load of research and eventually settled on the De'Longhi ESAM4200 as a practical compromise from a huge amount of very messy Barista gear. I've found that I've had to run both the grind and strength controls at their extremes to get a decent cup and it's not quite measured up.

Time for a hack

The thing that's bothered me all along has been the grind - it's very course. The finest setting is a tiny bit finer than I would expect for a Cafetière, but a long way short of Espresso.

I've been wondering if I could tweak it to get finer grind and this is what I discovered...

WARNING

What this describes will certainly invalidate your warranty, likely damage your machine and may even have other effects (I'd imagine metal or other debris in the grounds and burning out the motor as likely possibilities), not to mention other safety and health risks.

Understand what we're doing here fully before attempting it and do this entirely at your own risk.

Process

First of all, ensure that the machine is completely disconnected from power. This is important since electrics will be exposed during this.

Then we need to get access to grinder. This is done by removing the screws on the back and sliding the side panel back and off.

This will expose the grinder and the adjustment mechanism.

We need to get a bit of extra space to work with here. For this the 3 screws below the beans hopper (silver heads in the photo above) will need to be removed. You could disassemble more but I've found I get enough flexibility in the plastic with only these screws removed.

It may also help to remove the adjustment knob in the hopper - for this pry out the plastic plug in the top and then unscrew it. It only fits on one way. The extra movement in the gear will help give you a little bit of extra space to work.

Then you will need to pry the small adjustment gear up (I used a flat screwdriver) and turn it by a tooth or two towards the course end without moving the larger gear on the grinder. This effectively shifts the adjustment to think that the current position is courser than before and so you can turn it down even finer.

Now, obviously some care is needed here. Making this excessively fine will likely see the grinder burs hitting each other, potentially putting excessive load on the motor, and probably a whole lot more. After this some special care is needed to ensure that nothing is going to break.

Testing

Reassemble everything, checking carefully that electrics is all good and nothing is missing before reconnecting power.

I would recommend leaving the adjustment as-is initially, and then press the button to brew and while the grinder runs gradually reduce the grind size paying attention to any strange noises or any other signs of problems.

Coffee is now much richer and closer to what I would expect from decent quality Espresso machine, and in fact I'm backing off the grind control since depending on the beans, the finest setting results in the pull taking way too long.