Consistent uneven extraction: close left to far right

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danzimm

#1: Post by danzimm »

Hey all,

Recently I started watching my bottomless portafilter more closely and found that my pulls are always uneven; they begin at the closest left corner and expand out to the furthest right corner. I was hoping the community could help me fix the unevenness.

In order to speak further let me use the following diagram of a puck:
  
 [3]    [4]   [5] 
 
 [====machine====]
 
   x   xxxxx  x
  xxx   xxx  xxx
 xxxxx   x  xxxxx
 
 xxxxx   x  xxxxx
  xxx   xxx  xxx
   x   xxxxx  x
 
 [2]    [1]    [6]
 
        [=]
    [handle]
        [=]
My extractions consistently start out with 1,2,3, a second or so elapses and then 4,5,6 begin flowing-- here consistently means I have observed this in my past 100 or so shots. Eventually the flow evens out and I get a single stream, but the colors are strikingly different (its clear that 1,2,3 are more extracted than 4,5,6).

In addition to the above, I've found that *sometimes* (not quite as consistently) the "crust" (if you were to imagine the above diagram as a pizza) of 4,5,6 start flowing before the inside of 4,5,6; i.e. the extraction starts off as: 1,2,3 -> 1-1.5 sec -> crust of 4,5,6 -> 0.5-1sec -> middle of 4,5,6.

Below is my procedure:
  1. Put 15g or 18g of beans in a dosing cup, spray a bit of water on them, shake-shake-shake
  2. Grind the beans in Weber Key (for lighter roast/harder beans I need to put the beans in at 3-4 at a time, otherwise I basically dump all the beans in that I can)
  3. Remove portafilter from group head, place on tamping mat. Twist, pop-unlock and drop the Key's magic tumbler and place it on top of the portafilter
  4. Spin the inside pawn upward so that all the grounds fall into the portafilter. Additionally I spin the portafilter + magic tumbler around a bit to ensure all the grounds land in the portafilter as evenly as possible. I try to follow what this video from Weber does.
  5. Here I have tried a few different pre-tamping strategies:
    1. Nothing: this results in the most uneven extractions
    2. Use Saint Anthony Industries BT Wedge at its maximum tightness (i.e. least extended, in order to reduce the chance of accidental tamping/try to rake as much as possible): better than (a) in evenness, but the extractions are more volatile (the amount of channeling between pulls varies)
    3. Tap the portafilter on the tamping mat to try and settle the grounds, then used Saint Anthony Industries BT Wedge as above: about the same as (b)
    4. Rake the top of the grounds with a sim ejector to even it out: about the same as (b), but less volatile
    5. Rake the top of the grounds so that regions 1,2,3 have slightly more grounds than 4,5,6: about the same as (b)
    6. Stir the grounds with the tumbler still on with home-made WDT tool (combination of a cork + 8 of the 0.4mm needles from here). After stirring I remove the tumbler and do a quick raking to double check that everything is level
  6. Tamp with the Decent self-leveling tamper (v4). I have tried tamping with minimal pressure to entirely compress the spring and with some additional pressure (just in case...)
  7. Insert portafilter into Lelit Bianca grouphead, turn on the Bianca with the flow paddle completely open
  8. Observe uneven extraction as described above
Here is a video of me carrying out the above procedure with 5f's pre-tamping strategy. The extraction in this video is about the best I can possibly get. Note: this is not a typical extraction. There is usually a much larger delay between 1,2,3 and 4,5,6 extractions (extraction starts at 1:16-- use < 1 playback speed really see the issue.. or just see the pre-infusion video below):
Here's a second video demonstrating the uneven extraction (with 5f's strategy again), but this time with a bit of pre-infusion. This is a more typical extraction for me (thankfully pre-infusions seems to eliminate the spraying...):
Here are some scattered additional observations (in case they're useful for debugging):
  • Sometimes it seems like liquid is coming down outside the basket in region 2. When this has occurred I immediately popped the basket off after the pull and confirmed there was liquid outside the basket (:o)
  • Most of the times I have some sort of spraying. It seems like half the time it's a large spray that lasts the entire pull, while the other half of the time it stops at some point midway through the pull. The spraying almost always happens in regions 1,2,3
  • When dumping the puck I've observed that regions 4,5,6 are usually darker. Upon squishing them they seem less sandy than the rest of the puck (more like mud)
Below are the troubleshooting steps I have taken:
  • Ensured the group head is level (interestingly with the legs fully screwed in the grouphead is not level on my Bianca)
  • Backflushed
  • Used nylon brush and microfiber towels to clean water dispersion component (i.e. underneath the shower screen)
  • Tried both the IMS E61 200 RNT (with Cafelat Silicone gasket) & stock Lelit shower screens (with stock rubber gasket)
  • Rotated the shower screens (in case the shower screens had asymmetries)
  • Pushed the shower screen gaskets as far in as I could (without breaking anything)
  • Rotated the basket in the portafilter (in case the basket had some asymmetries)
  • Used 2 different baskets:
    • Stock Lelit IMS 14-18g basket
    • Stock Lelit IMS 18-21g basket
  • Tried 3 different kinds of beans from light-medium to medium-dark; one of the kinds I tried both non-frozen and frozen variants (I let the frozen variant come to roughly room temp before using them)
  • Used stock Lelit 58.55mm tamp. This resulted in generally less even extractions, though with the same general trend as above (so I guess my investment in the Decent tamper was a good idea...)
  • Observe the water flow in the following situations, but did not observe anything of note (meaning to my naked eye they all to released water relatively evenly)
    • No shower screen
    • IMS shower screen
    • Lelit shower screen
    • IMS shower screen with bottomless portafilter
    • Lelit shower screen with bottomless portafilter
  • Used various pre-infusion times & pressures. When the pre-infusion is long enough the delay between 1,2,3's extraction and 4,5,6's extraction is within half a second, but the asymmetry still exists.
  • Pulled shots between 7am-7pm
  • Used different glasses when pulling shots with and without Acacia scale underneath the glasses
  • Played with my cats before pulling a shot

    Below is a list of research I've read/watched before making this post: Additionally I've read various forum posts on HB & reddit... but I may have missed something. If that's the case please forward me to the right information. Let me know if any additional videos/images would be helpful for diagnosing what's going wrong (as this post is already very long, I didn't want to include any possibly superfluous media).

    I've spent hours trying to diagnose what's going on alone, so I will not be offended if anyone points out that I'm doing something clearly stupid. I will only be thankful.

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cafeIKE
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#2: Post by cafeIKE »

Too much bling and too much massaging.

ASAPANS: As Simple As Possible And No Simpler

N E V E R will I understand why home baristas think they have to massage the life out of the coffee when they have a supremely espresso capable grinder. Distribute the coffee as simply as possible, level tamp, lock, pull, enjoy.

Sunday I went to Tried & True in Corvalis. They serve a lighter roast blend ground in a big Mahlkonig. The barista removed about ¼g to meet their 19g dose, tamped & pulled excellent shots. R E P E A T E D L Y. NO massaging. Oh yeah, the barista was a trainee with only a few weeks experience...

danzimm (original poster)

#3: Post by danzimm (original poster) replying to cafeIKE »

I think I was being a bit overly performative in the previous video. Here's a more accurate video of what I usually do. Is this still too much futzing about? Just for clarity's sake (sorry I'm kinda stupid sometimes) can you point out specific moments in the video that should be either cut out or sped up? Cheers-- thank you for taking the time to help out :)

CoolHandLukey

#4: Post by CoolHandLukey »

Curious - Do you observe the same extraction pattern(s) if you do not use the WDT tool?
danzimm wrote:I think I was being a bit overly performative in the previous video. Here's a more accurate video of what I usually do. Is this still too much futzing about? Just for clarity's sake (sorry I'm kinda stupid sometimes) can you point out specific moments in the video that should be either cut out or sped up? Cheers-- thank you for taking the time to help out :)

video
Death is not evil let alone the worst of evils. 'Live free or die'

Grant

#5: Post by Grant »

As mentioned, yes, way overkill on the shot prep (but i don't see how that would impact the shot anyways), but it seems to me that your tamping technique - the way you both hold the tamper and apply pressure, seems like it could easily create an uneven puck. Lack of pressure control. Far too much opportunity for pressure to be applied more to one side of the puck. You may be "consistently" apply uneven pressure while tamping...doing the same thing repeatedly, creating similar results each time.

Try this...after distributing the grinds, gently place the tamper on top of the grinds and see if it sits level. Apply gentle pressure to the tamper and grinds using 4 points of contact around the edge...your thumbs and two fingers at equal points around the portafilter, You can easily feel if anything is uneven doing this. Then gently apply even and increasing pressure to the puck at all 4 points. Do not use the handle of the tamper...only the tamper surface and edge of the portafilter as a guide. Apply more even pressure to ensure an even tamp...then try another shot and see what happens.
Grant

danzimm (original poster)

#6: Post by danzimm (original poster) »

CoolHandLukey wrote:Curious - Do you observe the same extraction pattern(s) if you do not use the WDT tool?
Yes unfortunately :( see the video below:

danzimm (original poster)

#7: Post by danzimm (original poster) »

Grant wrote:As mentioned, yes, way overkill on the shot prep (but i don't see how that would impact the shot anyways), but it seems to me that your tamping technique - the way you both hold the tamper and apply pressure, seems like it could easily create an uneven puck. Lack of pressure control. Far too much opportunity for pressure to be applied more to one side of the puck. You may be "consistently" apply uneven pressure while tamping...doing the same thing repeatedly, creating similar results each time.

Try this...after distributing the grinds, gently place the tamper on top of the grinds and see if it sits level. Apply gentle pressure to the tamper and grinds using 4 points of contact around the edge...your thumbs and two fingers at equal points around the portafilter, You can easily feel if anything is uneven doing this. Then gently apply even and increasing pressure to the puck at all 4 points. Do not use the handle of the tamper...only the tamper surface and edge of the portafilter as a guide. Apply more even pressure to ensure an even tamp...then try another shot and see what happens.
Ah, thank you for clarifying! Unfortunately with the Decent Tamper (note: this is not me describing the tamper- that's the name of the tamper :/) that I'm using I can't use the technique you described. Further I'm copying the tamping technique seen here from the makers of the tamper: http://www.youtube.com/watch?v=HIexlhxP0Ig (go to 8:31 to see the tamp... unfortunately the timestamp is stripped from the url when I submit this post)

Regardless, I pulled out my Stock Lelit Tamper and made a shot with the technique you described (unfortunately the extraction is still uneven)-- is this what you meant/can you critique this video?
Again-- I am SO appreciative, thank you :D

Grant

#8: Post by Grant »

danzimm wrote:
I pulled out my Stock Lelit Tamper and made a shot with the technique you described (unfortunately the extraction is still uneven)-- is this what you meant?
Yeah...dead on to what I was suggesting. It would seem to me then that if it is consistent, that it comes down to something with the portafilter basket, or perhaps the portafilter and water flow of the machine?

Are you always using the same basket?

Also, I know my machine (Elektra A3) is very aggressive when it comes to water flow...rotary pump slams the puck with full pressure with no ramp up at all or pre-infusion. Do you have a video of the water flow out of the group head WITHOUT the portafilter inserted? Is there a more aggressive water flow from that side of the group head? I have started using a stainless steel puck screen which has helped immensely...but you can emulate this by using an Aeropress filter (or just cut a coffee filter to size) and placing the paper filter over the puck before inserting it into the group head, then trying the shot. The filter will diffuse the water flow more evenly.
Grant

CoolHandLukey

#9: Post by CoolHandLukey »

The tumbler doesn't necessarily distribute grounds as evenly as desired. Keeping your basket as level as feasible, try this tumbler technique with no WDT - http://www.youtube.com/watch?v=MUiye0lCe0M

Reviewing the extraction for the above video, you can witness how his puck prep caused a donut extraction.
With no WDT, is there a ring-shaped divot when you remove the tumbler from the basket and prior to tamping?

Assuming an even tamp, It seems you have more espresso opposite the portafilter handle. You can confirm this hypothesis by keeping your current puck prep and turning your basket 180 degrees in the portafilter prior to extraction observation.
danzimm wrote:Yes unfortunately :( see the video below:
video
Death is not evil let alone the worst of evils. 'Live free or die'

danzimm (original poster)

#10: Post by danzimm (original poster) »

CoolHandLukey wrote:The tumbler doesn't necessarily distribute grounds as evenly as desired. Keeping your basket as level as feasible, try this tumbler technique with no WDT - video
Thanks for the link-- I tried out the technique shown (keeping the basket as level as possible) but still had the uneven extraction.
CoolHandLukey wrote: Reviewing the extraction for the above video, you can witness how his puck prep caused a donut extraction.
With no WDT, is there a ring-shaped divot when you remove the tumbler from the basket and prior to tamping?
Yes-- I'm guessing that's why I'm getting a donut extraction, but there still seems to be some unevenness :/
CoolHandLukey wrote: Assuming an even tamp, It seems you have more espresso opposite the portafilter handle. You can confirm this hypothesis by keeping your current puck prep and turning your basket 180 degrees in the portafilter prior to extraction observation.
Unfortunately after doing this I still get the uneven extraction :/

I will post a video highlighting the above tips in a bit... see the next video I'm about to post for a surprise that might be the source of the issue...