I recently switched from the stock screen to an HQ screen after about 6 months and it's the first time I've done this on the machine.

I am noticing that when I flush, the water comes out in a cone in the center of the screen with nothing on the edges. The results in the cup recently, after the change, have included early blonding in the center. This leads me to believe that it's not getting an even distribution. Are there any procedures that you use to alleviate this? Is this typically how an E61 works? I don't remember seeing this with the old screen, at least not so severe.

thanks!

I'm surprised that you are seeing much of a difference in the water distribution as the HQ screen is just a high quality version of a standard E61 screen. I used then in several machines with no issues before switching to the IMS 200 screens.

I think this is just caused by surface tension and the way the water reacts on the screen. Once the "void" above the coffee and below the screen is filled with water during an extraction, so long as the water is not gushing in a strong stream in one location I do not think that the way the water exits the screen matters much (likely, not at all). Try pre-infusing for around three to five seconds to see if anything changes.

Before attributing too much cause/effect to the shower screen, search on "transparent portafilter" and watch the videos:
From Stephen Sweeney's TPF - a Transparent PortaFilter

As Randy notes, unless the initial diffusion is really uneven (e.g., due to updosing and crashing the puck into the screen on lock in), I'd look elsewhere for a culprit.

Thank for the responses. I'm first to admit I know little on the matter but I don't have much of a reference point except I've seen videos that look different than mine (for whatever reason). It just seemed like too big of a coincidence but I'll tinker more. I just wanted to eliminate obvious things that I might be missing.

It appears that the plate above the shower screen shoots straight down in the center. Then the center of the shower screen does not have holes so it would blunt the attack I'd think.

Just when I thought I fixed the channeling!

Take the screen off and turn on the brew cycle. I think you will find that the water does not shoot straight down. There is (or should be) a dispersion part in there. If it is like most other E-61s, if you remove that part and try again, the machine will peepee on you, shooting water out in a solid steam, pretty much right at your zipper.

Randy G. wrote:...if you remove that part and try again, the machine will peepee on you, shooting water out in a solid steam, pretty much right at your zipper.

Randy's correct. Please don't ask how I know.

And you just revealed how I learned that lesson. it's not bad unless the machine has been on for a while and the boiler and group are fully to temperature.

"Just look at that fellow- he can really dance!"