E61 Shower Screen Dead Spot

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pj.walczak

#1: Post by pj.walczak »

Hi,

In classic E61 shower screen there is a deadspot in the center.

I wonder why it is there?

On the CafelatStore, there is this statement: "The dead spots are crucial for E61 machines, (...)." (there is a custom screen for levers, without the dead spot).

However now I see, that E&B started to offer screens with much smaller dead-spot and advertising it as suitable for E61.

I am curious if anyone knows why the dead spot is in the original shower screen, and if crucial, why?
---

Pawel

Nunas
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#2: Post by Nunas »

I don't know for sure, but suspect it has to do with creating a laminar flow of water across the screen. If there were no dead spot, the water exiting the hole in the middle of the group head would tend to flow more through the middle holes than those farther out.

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BaristaBoy E61

#3: Post by BaristaBoy E61 »

I would recommend installing an IMS 200 E61 Competition shower screen for all E61 groups.
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

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cafeIKE
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#4: Post by cafeIKE »

Having tried many e61 shower screens, the only valid variable is the height which affects headspace. If the puck is hard up against the screen, a large center might affect initial wetting, but once the pressure builds and the puck compresses, the pressure is the same across the entire puck surface. Water flows pretty evenly through a puck.

A long while back in 2007, I experimented with just a tiny shot of water on the puck. There is a small dry spot in the center, but it's wet long before the pressure begins to build.


I also tried several baskets, shower screens and modified water spreaders.




The only thing that mattered was the coffee depth and headspace. Hole patterns, center dot, spreader flow. Nada. Sorry, I don't recall the difference between 2nd from left spreader and rightmost... I may have drilled the holes a bit larger :?

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HB
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#5: Post by HB »

cafeIKE wrote:Having tried many e61 shower screens, the only valid variable is the height which affects headspace. If the puck is hard up against the screen, a large center might affect initial wetting, but once the pressure builds and the puck compresses, the pressure is the same across the entire puck surface.
Several threads and videos confirm what you're saying.
Mohammad wrote:For years I've read about Illy's one and seen a photo of it but never seen a video of it in action. Look at what La Spaziale has done!

Bad prep
Good prep
Also see Stephen Sweeney's Transparent PortaFilter and FINALLY! Transparent portafilter espresso extraction videos and New transparent portafilter design (with video).
Dan Kehn

baldheadracing
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#6: Post by baldheadracing »

Perhaps this is only a concern when there is a high water debit, like with a multi-group-sized rotary pump.

The reverse seems to make a difference; the odds of channeling seem to go down in a high-debit system feeding a lever group when changing from an IMS200 E-61 screen to an IMS200 screen with center holes (or my puck prep improved when I changed screens).

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JohnB.
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#7: Post by JohnB. »

I don't know about the E61 groups but Kees has been supplying his own version of the IMS 200 screen with the center drilled for years for the Speedster & his other machines. They work great with his saturated groups.
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cafeIKE
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#8: Post by cafeIKE »

JohnB. wrote:Kees has been supplying his own version of the IMS 200 screen with the center drilled for years
Any data to support the need?

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JohnB.
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#9: Post by JohnB. » replying to cafeIKE »

Evidently Kees felt that it worked better with his machines or he wouldn't have continued using them. I've used them for 5-6 years in my Speedster & also use the Cafelat lever version in my Bosco. Kees' version leaves the very center spot undrilled while the Cafelat screens have a hole there. It's been quite awhile since I've had a standard IMS 200 screen in either machine so I can't offer any comparision.
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