ROK and The Zen of Espresso Machine Maintenance

Worth giving this another shot?

Posted on August 24, 2025 by Carolyn Donovan and Wan Chi Lau in RainyDayKitchen // 0 Comments

ROK is a group of product designers who, in 2002, took on the engineering/innovation challenges of making espresso manually at home. Their approach harnessed the mechanical advantage of a simple machine, the lever, to generate the 9-bar of pressure necessary for proper espresso extraction.

We got the original ROK manual espresso maker over 12 years ago! We planned on writing the FirstLook/FirstUse on the unit, but we were never able to pull a hot, decent cup of espresso from it. After a while, we gave up, shelved it in the back, and essentially forgot about it.

The original kit contained:

Made from chrome-plated die-cast zinc and stainless steel, the portafilter basket is big enough to hold 16-20 grams of coffee, enough for a double espresso. The levers are geared to generate the 9-bar pressure for the perfect extraction. A splitter can be fitted to the bottom of the portafilter to make two single espressos.

With just a few strokes of the ROK pump-action hand frother, turning milk into microfoam is easy and quick, and perfect for flat white, cappuccino, and macchiato beverages. The frother works equally well with non-dairy milks.

NOTE: Readers new to RainyDayMagazine might be wondering why we didn’t do a write-up on the ROK 12 years ago. The reason is that there is a lot of gear in the world. If it works and we like it, we’ll tell our readers about it. Otherwise, we won’t.

This long-standing policy saves our readers time. Over the years, readers have come to expect that, if it is written up in RainyDayMagazine, they can be sure it is worth their time to read about it. Period.

ROK

During a recent “gear cull,” the ROK was rediscovered by our new RainyDayIntern, Reese.

He thought the device looked interesting, the manual process intriguing, and was game to see if the ROK was worth another shot (see what we did there?).

What Reese had found was that there is now a conversion kit that will upgrade the original ROK unit to an EspressoGC!

GS Conversion Kit

The cylinder and plunger are made with a glass-composite, which is really tough and should last for a good long time. The screen and o-ring are made with silicone.

Removal

The steps to install the GS conversion kit are very well laid out in the video created by ROK. We found the process simple, easy to follow, and did so without issue. However, we thought it would be instructive to call out some of the key points along the way.

No tool is needed for the disassembly and removal of the old chamber.
A quarter (aka “a twenty-five cent piece” for those of you completely online) fits the slot of the screw connecting the lever arms.
Lifting the lever arms made the removal of the screw easier.
Corrosion of the aluminium can make the old chamber difficult to remove.

Installation

With the basket and old screen out, the installation of the new basket and screen was the next step. The basket clicked in easily, but fitting the silicone screen took more time. Getting the screen’s tabs into place was fiddly, but ultimately doable.

Once the basket and screen are in place, the final step is to reconnect the lever arms to the plunger.

Reassembly

We pushed the plunger down to reconnect the lever arms, but realized afterwards that it wasn’t necessary. It would have been easier to leave the plunger at the top and lift the arms instead.

Aligning the holes of the two lever arms to those of the plunger was easy. We had a little bit of trouble pushing the pin through, but once we did, locking the pin in place was just a few quick turns of the screw.