Thanks, @K7. I was starting to wonder if the weight was substantially greater. And yes, you're right that the water mass isn't going to be the same for every machine.

Well, anyways, it's easy to include the screen when preheating basket so it's only extra work if you just want to preheat the screen.

Hello everyone,

Since two days (have the Robot since one year) I've tried preheating and indeed the taste of lighter roaster coffees is much improved. Am quite happy with the taste now. Before doing this these coffees were quite sour. So thank you for the tips

But... because I preheat with hot water in a cup and placing the piston in the cup, the seal gets wet, looses the lube and then leaks at the start of the shot. I guess that the seal does not flair out as intended at the beginning when almost no pressure is applied. During the shot it doesn't leak. When I wasn't preheating I had no problem.

How do you preheat the piston without dipping it in hot water? Thanks.

Wipe the gasket, that solves it for me. So I guess it's actually more initial friction.

Ok, thanks for the tip. Will try. I assume that means that the gasket will get damaged faster.

Not that I've noticed since I started doing it over a year ago. Still on my first gasket, now more than 3 years old.

@Jonk: Thanks a lot!
An unrelated question: do you have a preferred dose of coffee in? I'm only doing 19g in, but don't have any particular reason to do it like that. Did you find you need to tweak your dose?

I'm usually dosing around 16g. The main reason is that I don't want stronger / more coffee. I think larger doses work fine or perhaps slightly better, but don't like dosing much less.

vladgiurgiubv wrote:@Jonk: Thanks a lot!
An unrelated question: do you have a preferred dose of coffee in? I'm only doing 19g in, but don't have any particular reason to do it like that. Did you find you need to tweak your dose?

I do 16g for a "small" americano (total volume of the cup is 250ml or 1 measuring cup) and 20g for a "large" size, which takes about 1.5 cup. After some experimentation with different doses I landed on these two as an optimal solution. I didn't want to waste beans with larger doses if I didn't have to, they are quite expensive for premium quality.

I now dose 14g. It's yielded the best results with the least channeling, while still making a 28-30g shot.

vladgiurgiubv wrote:... because I preheat with hot water in a cup and placing the piston in the cup, the seal gets wet, looses the lube and then leaks at the start of the shot...

...How do you preheat the piston without dipping it in hot water? Thanks.

If you're careful you can arrange the pre-heat water level so that just the tip of the piston is submerged. The piston will still get wet and warm from the steam but at least it won't be taking a bath. Maybe it will help.

I've wondered if preheating the piston accelerates aging of the seal. My current seal started getting harder and harder to lock in, something that has in the past meant that the seal would start failing before too long. But for the last couple of weeks I've been using a coffee that does not ask for any preheating and locking in has become much easier. So now I wonder again if preheating is the culprit.