These filters probably reduce the water pressure as seen by the puck. Does anyone know by how much? Should be easy to measure if you have a Scace. I guess you would need a Scace-like device that can work with a screen in the basket.

why/how would they reduce pressure at the puck? the screens are porous and the whole system is pressurized. I can't think of how they would reduce pressure at the puck.

I'm not surprised you're getting more drips during preinfusion than you're used to, since the screens helps more evenly distribute water and increases saturation speed of the puck.

baldheadracing wrote:These things look interesting - but something confuses me - what is meant by the group getting dirty? Is this like grounds on the dispersion screen, like in a pump machine with a three-way valve? Or?

A commercial lever machine is quite low maintenance by design. However, there's always a bit of coffee grounds and oil that stick to the shower screen and inside the group. An open port flush (I do it with a portafilter wiggle) cleans most of it though.

My main reason for wanting one is simply because I use one with my gen2 Europiccola and it does absolute wonders. Improves forgiveness, consistency and keeps the group super clean.

During the day, my wife also pulls espresso on the Londinium and we obviously don't have the same exact puck prep and routine. A puck screen adds some forgiveness when her prep is not 100% spot on and it also keeps the group cleaner, which is nice for the next person to use the machine

sethde wrote:why/how would they reduce pressure at the puck? the screens are porous and the whole system is pressurized. I can't think of how they would reduce pressure at the puck.

I'm not surprised you're getting more drips during preinfusion than you're used to, since the screens helps more evenly distribute water and increases saturation speed of the puck.

In my initial post I explained that I'm not getting normal preinfusion drips. I get watery messes. No matter the dose, head space, lever manipulation or grind finess. It's simply not agreeing with the way the pressurized water hits the puck. It behaves very differently on my Londinium vs the Flair58 or other commercial groups.

The puck screen prevents the puck from expanding up into the group head screen when it's depressurized, which helps keep the screen clean.

baldheadracing wrote:These things look interesting - but something confuses me - what is meant by the group getting dirty? Is this like grounds on the dispersion screen, like in a pump machine with a three-way valve? Or?

When I think of the headaches that would solve with a Gaggia Classic clogging up its valve and mucking up the group!

BruceWayne wrote:The puck screen prevents the puck from expanding up into the group head screen when it's depressurized, which helps keep the screen clean.

And then you have to clean grounds off the puck screen so how is that less cleaning?

After a shot, I wash the puck screen at the same time as I clean the portafilter and basket. Under the sink or PF wiggle inside the group. Much faster than using the brush or the Espazzola. Less chances of grounds migrating through the shower screen, under the piston and inside the group bore.

Again, it's definitely not a necessity or as much of a game changer as it is on the gen2 LPE... but... I prefer a dirty puck screen over a gonked up group when comes maintenance time. Also, I HATE removing the IMS shower screen on my Londinium. A pita. Happy to know it won't be part of maintenance anymore.

sethde wrote:why/how would they reduce pressure at the puck? the screens are porous and the whole system is pressurized. I can't think of how they would reduce pressure at the puck.

Not a static and closed system here... Water is flowing and when the flow is restricted by something, pressure drops. Think a kinked hose or the E61 flow restrictor for pressure profiling. The drop could very well be quite minor in this case, I don't know.

In the electric world of a 3 way valve, one of these really reduce the amount of cleaning required due to fowling of the 3 way components. But in the simplified world of a piston/spring driven group lacking a 3 way valve, you're still benefiting not putting any ultra-fine coffee schmootz up there into the upper assembly which would likely increase corrosion on parts like the spring. I'd much rather keep that whole area clean and devoid of anything that exacerbates corrosion or wear on the seals o spring.