Uneven extraction on bottomless portafilter [SOLVED]

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JayBeck

Postby JayBeck » Jul 02, 2018, 11:09 am

UPDATE: See bottom of this initial post for the solution I found.
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My Problem:
Uneven extraction on bottomless portafilters and a subsequent unlevel puck after the shot.

The Background:
I haven't used a ridged basket in a while so when I used one over the last week I began to notice that the puck started level after being tamped and after the shot it was unlevel. The unlevel part is where the puck first starts to bead. No matter how much WDT, lately all my shots seems to start beading on the right before the left. Sometimes they end up coming into a single stream but there is definitely a pattern.

I have tested everything I know to test. I use an IMS screen but have also tried (with similar results) on the stock shower screen. I have put a level on my counter top, various parts of the machine, group, basket, portafilter, etc. Everything is level.

WDT with Kafatek tools helps but does not eliminate. I use a LevTamp and have tried lighter tamping and harder tamping. I use VST baskets so I have tried going back to stock; stock baskets aren't quite as sensitive but still exhibit the same behavior. I have used all E61 preinfusion tricks to lengthen the time for the puck to saturate (trickle PI, pump on then off for several seconds, etc). It just seems like the water flow is just favoring the right side.

My Theory:
After reading the plethora of information on here on possible fixes with nothing really helping, I started reading more about the E61 water dispersion. Apparently, that screw in the group doesn't do a great job of even water flow, which the screen is supposed to fix. I feel like my water is just more pronounced to the right side for whatever reason and the screen isn't offsetting this enough. Are there any 'tune ups' that can be done to that screw?

I've been going through a lot of coffee. I had originally thought my issue was head space; however, I did the Schulman 'dial in' method Friday using the stock basket down to 14g and again, while not bad, it still favored the right side and had a gentle slope to the right when done.

You hear a lot on here about how 'forgiving' an E61 group is but man this has been frustrating. Any other ideas?

NOTE: I'm using a Sette right now but I had similar experiences using a Monolith Flat so I do not believe the grinder has anything to do with it.

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UPDATE 7/7/17. My Solution:

After changing to a thicker gasket and inspecting my prior gasket, and pulling about a pound of coffee, I am ready to say that I have found the solution. I am so relieved to know it has nothing to do with my machine / grinder / technique. It also wasn't entirely about the size gasket I was using. I think 8.5mm is recommended but the 8mm is not what caused my issues.

My gasket was either warped or a lemon from the OEM. I got the idea to measure the size of my gaskets from a user posting about measuring his to be 8.2mm. I have always assumed the stock Profitec ones were 8.5mm based upon what WLL told me in a chat. I started by measuring my stock gasket which was around 8mm. I believe that it was originally 8.5mm but after 6+ months of use it had compressed to 8mm (same with the user whose is now at 8.2mm -- i'd say it started at 8.5mm). From what I understand on stock style gaskets, this is normal due to them being rubber and being compressed / heated / cooled etc. It also makes sense because the PF had locked in closer to 5PM instead of 6PM prior to me switching out for Cafelat.

So let's talk about the Cafelet gaskets. I bought both the 8mm and 8.5mm gaskets. I found the 8.5mm a bit tight so I had been using the 8mm. I had a little issue installing when it was brand new but eventually got it installed. For nearly 6 months I've had some issues that seemed to be getting worse. I assumed it was coffee, or the grinder, and then my machine which started this thread. It had nothing to do with any of those. I measured the thickness of the gasket this morning. Low and behold it is 8mm in places and in one quadrant it is 7-7.5mm. Whether this is compressed/damaged from my first installation or a lemon gasket, I'm not sure. But now it all makes perfect sense: uneven pucks, extreme channeling, etc were caused by the gasket sealing unevenly.

I had never thought about measuring the uniformity of my gasket. What a simple fix. Back to picture perfect pours!

User avatar
Jake_G

Postby Jake_G » Jul 02, 2018, 12:48 pm

Jayson,

A really quick and easy test to completely rule out basket prep is to do everything you normally do and then right before you lock the portafilter in, spin the basket 180° in the portafilter.

If the flow still favors the right side, then water flow could be a factor. If the flow favors the left, you still have unresolved distribution issues to deal with. My bet is on the latter, but either way this test will be informative.

Good luck and keep us posted!

- Jake

wsfarrell

Postby wsfarrell » Jul 02, 2018, 1:07 pm

Impressed with the Chris' Coffee video of the IMS screen, I too bought one. It made absolutely no difference whatsoever in the visible dispersion of water from the group. 2-3 large bubbly streams before, 2-3 large bubbly streams after. I'm wondering if anyone has been able to achieve the fine spray shown in the video with one of these screens.

JayBeck

Postby JayBeck » replying to wsfarrell » Jul 02, 2018, 1:30 pm

The IMS screen doesn't require a brush to clean (at least the NanoQuartz doesnt). That's the main reason why I like it.

User avatar
HB
Admin

Postby HB » Jul 02, 2018, 1:35 pm

JayBeck wrote:...I did the Schulman 'dial in' method Friday using the stock basket down to 14g and again, while not bad, it still favored the right side and had a gentle slope to the right when done.

It may be something as benign as your machine is unlevel? In general, the initial beading and first few seconds are the best indicators of the evenness of the extraction. The meandering of the espresso stream prior to formation of a cone doesn't necessarily indicate channeling.
Dan Kehn

User avatar
BaristaBoy E61

Postby BaristaBoy E61 » Jul 02, 2018, 2:08 pm

Have you tried replacing the group gasket holding the dispersion screen?


I too first thought about the dispersion screw. If you've check it out then perhaps it can be ruled out.

We too use the IMS dispersion screen & an 18gm VST ridged basket, WDT before a Mahlgut Palm distribution tool and flat tamper. We're direct plumbed and use line pressure preinfusion but don't experience the problem you're experiencing. This is quite a mystery. Please keep us posted.

BTW: I do give the IMS dispersion screen a quick wipe down with a clean napkin after every shot.
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

JayBeck

Postby JayBeck » Jul 02, 2018, 2:26 pm

HB wrote:It may be something as benign as your machine is unlevel? In general, the initial beading and first few seconds are the best indicators of the evenness of the extraction. The meandering of the espresso stream prior to formation of a cone doesn't necessarily indicate channeling.


I saw some posts about unlevel machine causing a similar problem by Cannonfodder (I believe) so I put a level on the counter (level); the frame near drip tray (level); top of the machine (level); the E61 Group (level); the basket bottom in the PF while locked in(level). I was hoping for a simple solution. I have also eyeballed the screen to see if it is bent but it appears normal.

JayBeck

Postby JayBeck » Jul 02, 2018, 2:30 pm

BaristaBoy E61 wrote:Have you tried replacing the group gasket holding the dispersion screen?


I too first thought about the dispersion screw. If you've check it out then perhaps it can be ruled out.

We too use the IMS dispersion screen & an 18gm VST ridged basket, WDT before a Mahlgut Palm distribution tool and flat tamper. We're direct plumbed and use line pressure preinfusion but don't experience the problem you're experiencing. This is quite a mystery. Please keep us posted.

BTW: I do give the IMS dispersion screen a quick wipe down with a clean napkin after every shot.


How do you check out the dispersion screw? I read they can be hard to unscrew. I'm not really sure what to look for.

I have 8mm, 8.5mm Cafelat gaskets and the stock Profitec one. I use the 8mm one but I get the same effect with Profitec or 8mm Cafelat. I have not used the 8.5mm Cafelat since the first time I had it due to my PF not being in tight enough and falling out of the machine (lol).

Actually at first last week i thought I had over cranked the gasket causing the PF to be favoring the right side but I've since followed the official 'ECM' technique (Youtube Video) for installing the gasket / screen and got the same effect so that doesn't appear to be it.

BaristaBob

Postby BaristaBob » Jul 02, 2018, 2:55 pm

Jayson,

Not that this is a fix, but have you tried shimming the right side of the machine to try and even the flow just to see what that might do? Again it might help to isolate the problem. If it helps it might mean you have a non-uniform flow from the group head, or somewhere, somehow the machine is not level, or you do have a warped screen.

This is a puzzling issue.
Bob "hello darkness my old friend..."

Bret

Postby Bret » Jul 02, 2018, 3:36 pm

I was thinking the same thing: trying a shim might be informative.

I also wonder if you have been able to inspect the flow path above the screen? The only thing I can think of is some build-up there that is causing uneven flow under pressure (which might not cause a visible imbalance when flushing),