I see discussions on different platforms crop up from time to time where someone "adjusted the level of their machine", but what I can imagine is a degree or two at most, and magically their espresso is wonderful and perfect and all channeling problems they once had are resolved. They've reached espresso nirvana with this "one trick".

I'm obviously skeptical of this, as I don't see how a puck under 130+ psi of pressure is going to react much differently to a degree or two of level. Pour over or drip, maybe?

Anyways, looking for thoughts or some sort of evidence on the topic.

I'm tempted to grab some shims and run some side-by-side tests on my own rig.

Many confuse an off center pull with channeling. If the group face is not level, the pour can be off center.

First thing to check [on e61 at least] is the group face is level - in both axis. If it's not, either reposition or shim the feet.

I get that, for sure. But do you think that a a slightly off-center machine is going to cause channeling or otherwise lower the quality of your espresso?

Again, I'm talking about level variations on a typical countertop or old home, for example.

We're talking about a chamber pressurized to 9 bar. Other then affecting the way the espresso stream pours after existing the basket, no, I don't believe variations in levelness matters. If someone could tell apart two espressos in a blind taste test-- one poured from a perfectly level machine and another with the same machine tilted a few degrees --I would be amazed.

Ok but for real, im basically a primitive ape. Is there a layman's way to explain your findings?? This is fascinating work what with the numbers and the lines and big words.

If you're filling the basket slowly, an off-level machine, or one with relatively poor water distribution can result in uneven wetting of the puck. This can lead to uneven extraction (due to contact time) as well as channeling. "Can", not "will". With fast fill, the potential for uneven wetting is significantly less.

How level is "level enough" is something that I don't consider worth pursuing. If my counter is reasonably level and my machine isn't notably bent, it is probably good enough. If you do want to check, I'd recommend a good spirit level and strongly recommend against a phone's "level" program.

The math maybe correct for an internal portion of the puck, but what really happens is a viscous gas, liquid and solid blend sliding across the basket face under ZERO pressure.

Jeff wrote:If you're filling the basket slowly, an off-level machine, or one with relatively poor water distribution can result in uneven wetting of the puck.

Yes, but does this really matter? Even at low flow rate, we are talking about a second or two where the surface of the puck is not wetted evenly. The water itself does not penetrate deep into the puck when there is no pressure. Then the water fills the head space, then the pressure rises and then the water will flow through the puck. Thats where the absolute major part of the extraction starts, not on the surface.

cafeIKE wrote:but what really happens is a viscous gas, liquid and solid blend sliding across the basket face under ZERO pressure.

As you wrote, it is sliding across. The surface itself does not contribute much to the espresso compared to the rest of the puck.

Pflunz wrote:Yes, but does this really matter? Even at low flow rate, we are talking about a second or two where the surface of the puck is not wetted evenly.

See FINALLY! Transparent portafilter espresso extraction videos to see this in action.