Espresso diaries #2: bug fixing the ROK

I think the Rok is a great espresso machine. There is something very satisfying about pressing down those arms and producing espresso.

However it comes with many small problems that don't appear to have well documented solutions. I hope this helps another Rok user out there.

Preheating

Rok is a fully manual machine with a mostly stainless steel body. This meanss that will run into problems with temperature control especially if you live in the colder parts of the world. What I found to work best is to just plug the portafilter with a cork and then pour boiling hot water in the chamber, lift up the arms and let it sit there for 30 seconds. And only then fill the portafilter with coffee.

Preinfusion

I did have trouble getting good shots but it appears that it all came down to the preinfusion stage. So preinfusion is when you just let the water meet the coffee in the chamber at 0 or low pressure. At 15sec preinfusion it was not really good. To get the tasty bits out I would usually need around 25-30sec at 1-2 bars and then pull a 20-30sec shot.

Unwinding of the portafilter

So this was weird. In the beginning I had trouble with a very slow unwinding of the portafilter. The pressure build up was too high which made the portafilter slightly unwind and water droplets would overflow past the portafilter. I only noticed the droplets at first because the unwinding is at the order of mm. I only figured it out after making a video.

I contacted Rok and it took many emails back and forth to figure out what was wrong. We are still not completely sure why it occurred but it has stopped happening. It could have been some oil somewhere which made the surfaces slippery. Anyways, after I started using a bit of soap to clean out the wings of the portafilter and gasket it did not happen again.

Would love to know if people have recommendations for other manual espresso machines.

cat tax