You have provided a good amount of info, but there are still some important yet unanswered questions.

- Are you still using the Dragonfly Espresso beans? How old are your beans?
- Are you purging the grounds when you change the grind setting?
- What's the true zero point (burrs chirping) on your grinder? If it's "0", 0.7 from it seems awfully fine grind setting for 17g of medium roast espresso blends. If it's like -1.5 like mine was (so basically +2.2 from true zero), then it's probably within the range.

A video of your session (grinding, puck prep, and pull) would be nice. Often folks here can spot an issue much more easily that way. Too bad you don't have a naked PF, though. Reading your posts, I'm pretty sure you will end up getting one anyway, so you might as well buy one sooner!

Here's an idea. Caveat--I'm also a relative newbie and only slightly ahead of you on the learning curve, so this could be way off.

Let's assume for now that such wide variability is the result of channeling. If so, perhaps the most relevant shot times are not your average shot times (mean or median) at a particular grind setting, but rather your maximum (or maybe 90-95th percentile). Because, perhaps, the maximum most correctly represents the shot time resulting from a non-channeled puck with that grind setting and all your (significantly) faster shot times are only faster because they are channeling through a too-finely ground puck. If this theory is correct, even though you may be near the magic shot time numbers for your average shot times, you may find average shot times actually increase as you grind a bit coarser (because of reduced probability and magnitude of channeling) and then decrease again at coarser still, but now with more consistency.

As other posters, with far more credibility than I, have pointed out--a bottomless portafilter can help confirm something like this. I know that I only started getting (more) consistent timing when I stumbled onto a combination of grinder, grind setting, prep, tamping, etc. that resulted in a good-looking extraction on a bottomless, rather than spritzers and splatters all over.

K7 wrote:You have provided a good amount of info, but there are still some important yet unanswered questions.

- Are you still using the Dragonfly Espresso beans? How old are your beans?
- Are you purging the grounds when you change the grind setting?
- What's the true zero point (burrs chirping) on your grinder? If it's "0", 0.7 from it seems awfully fine grind setting for 17g of medium roast espresso blends. If it's like -1.5 like mine was (so basically +2.2 from true zero), then it's probably within the range.

A video of your session (grinding, puck prep, and pull) would be nice. Often folks here can spot an issue much more easily that way. Too bad you don't have a naked PF, though. Reading your posts, I'm pretty sure you will end up getting one anyway, so you might as well buy one sooner!

Thanks for this. Unfortunately, I'm out of Dragonfly beans. My last test was with Verve beans. They came with the grinder so I believe are fairly fresh. I'll have to check.

Yes, I am purging about 2g before changing grind settings or beans. Zero point is confirmed to be zero. Thank you for confirming: I don't have a frame of reference but 0.75 seemed to me also to be a very fine grind. That's helpful.

I'll see if I can do a video tomorrow perhaps. Maybe Friday. That'd be great.

markwhibbard wrote: ...
Let's assume for now that such wide variability is the result of channeling. If so, perhaps the most relevant shot times are not your average shot times (mean or median) at a particular grind setting, but rather your maximum (or maybe 90-95th percentile). Because, perhaps, the maximum most correctly represents the shot time resulting from a non-channeled puck with that grind setting and all your (significantly) faster shot times are only faster because they are channeling through a too-finely ground puck. If this theory is correct, even though you may be near the magic shot time numbers for your average shot times, you may find average shot times actually increase as you grind a bit coarser (because of reduced probability and magnitude of channeling) and then decrease again at coarser still, but now with more consistency.

Thanks for this, Mark. That makes a lot of sense to me. I'll try that. As others have pointed out, my grind setting of 0.75 above zero point seems awfully fine.

On the other hand, FWIW (is it worth anything?) I am not seeing any signs of channeling in my puck. It's firm and fairly solid. I do use a puck screen also, FYI. But yes, I'll try this.

As other posters, with far more credibility than I, have pointed out--a bottomless portafilter can help confirm something like this. I know that I only started getting (more) consistent timing when I stumbled onto a combination of grinder, grind setting, prep, tamping, etc. that resulted in a good-looking extraction on a bottomless, rather than spritzers and splatters all over.

Yeah, I'm getting the impression that that'll help me a lot. On my list.

Mark, than you for your comment/suggestion from your thread here: Expected shot time variability

markwhibbard wrote: Having read of your issues on the other post, I have a suggestion for an experiment you could run. Try grinding six or more doses all at once into a large container and thoroughly mixing the grinds. Then from that container make back to back shots and observe your consistency. if you are not achieving consistency, then there are factors other than your grinder and set up that are at least contributors to your inconsistency for example, distribution within your basket, tamping, dose size etc. However, if you do achieve consistency then you have pinpointed that your eureka machine is, indeed the source of your frustrations.

That was excellent. I didn't do six pulls, but I did do two trials where I grinded all beans at once, mixed them thoroughly, and used the mixed grind for three consecutive shots.

So for all three shots, 18g in, grind setting 0.75. Pre-infusion of 6 seconds with 35 seconds total shot time programmed into my Lelit Elizabeth (more respectable):
Shot 1: 38.5g, drip started at 7"
Shot 2: 40.0g, drip started at 6"
Shot 3: 43.0g, drip started at 6"

This compares with same settings (grind setting 0.75, 35" total time with 6" pre-infusion, 18g in, identical puck prep) but separate grinds for each pull (this is awful):
Shot 1: 41.3g, drip started at 10"
Shot 2: 38.2g, drip started at 10"
Shot 3: 26.0g, drip started at 10"
Shot 4: 51.4g, drip started at 10"


Similar results when using grind setting 0.75 with 15g in, and programmed 32 seconds with 8 seconds pre-infusion ...
With totally separate grinds for each shot (awful):
Shot 1: 36.3g
Shot 2: 32.0g
Shot 3: 60g

With grounds mixed together before extracting (more respectable):
Shot 1: 37.4g
Shot 2: 40g
Shot 3: 40g

That was informative. Seems to point more to grinder variables.

That sure is telling. The thoroughly mixed multi batch grinds seems about as consistent as you might hope for. Certainly seems to point to something in the grinder workflow and not dose, puck prep or machine.

Tesgin-2022 wrote:Thanks for this. Unfortunately, I'm out of Dragonfly beans. My last test was with Verve beans. They came with the grinder so I believe are fairly fresh. I'll have to check.

OK. Roast date should be on the bag. If it's been more than 3-4 weeks since the roast date, it might be a little to quite stale and could explain having to grind extra fine to generate puck resistance. If so, as I mentioned before, this in turn tends to make consistent and channeling-free extraction more challenging to achieve.

Yes, I am purging about 2g before changing grind settings or beans.

Um, you mean purge after changing the grind setting? You need to refill the grounds path after you adjust the grind setting. Also, although the Mignons have pretty low retention, you probably want to purge much more than 2g to be on the safe side, at least during this troubleshooting phase.

Your latest numbers for the single grind and mix method look quite good. Separate grind numbers, not so. Just to be clear, were those cases done with the regular hopper more or less filled with the beans (say, 50+% full)? You are not just throwing in 18g of beans into the empty hopper right lol?

Hmm, it's not clear what's going on...it seems there's some inconsistency in the way the grounds come out of the burr chamber and then the chute. Maybe some fines that were in the grounds path got dumped out for one grind session but not for the next session. I would think such scenario is more likely occur if in fact you are grinding stale coffee extra fine. Again, things tend to be more difficult when you work with very finely ground stale coffee, so I am not sure I would draw a hard conclusion at this point.

Also, how does it taste? If it's really fine grind, you might need to shoot for shorter ratio shot like 1:1 or 1:1.5 for best taste (at the current pressure of 9+ bar). Shot times will seem more consistent that way also because I suspect the current numbers include some gushing part at the end which unnecessarily makes weight numbers look wilder than they should be. Again, just offering possible explanations, not to suggest grinder issue should be ruled out.

Tesgin-2022 wrote: That was excellent. I didn't do six pulls, but I did do two trials where I grinded all beans at once, mixed them thoroughly, and used the mixed grind for three consecutive shots.

So for all three shots, 18g in, grind setting 0.75. Pre-infusion of 6 seconds with 35 seconds total shot time programmed into my Lelit Elizabeth (more respectable):
Shot 1: 38.5g, drip started at 7"
Shot 2: 40.0g, drip started at 6"
Shot 3: 43.0g, drip started at 6"

This compares with same settings (grind setting 0.75, 35" total time with 6" pre-infusion, 18g in, identical puck prep) but separate grinds for each pull (this is awful):
Shot 1: 41.3g, drip started at 10"
Shot 2: 38.2g, drip started at 10"
Shot 3: 26.0g, drip started at 10"
Shot 4: 51.4g, drip started at 10"


Similar results when using grind setting 0.75 with 15g in, and programmed 32 seconds with 8 seconds pre-infusion ...
With totally separate grinds for each shot (awful):
Shot 1: 36.3g
Shot 2: 32.0g
Shot 3: 60g

With grounds mixed together before extracting (more respectable):
Shot 1: 37.4g
Shot 2: 40g
Shot 3: 40g

That was informative. Seems to point more to grinder variables.

Yes, it does point to the grinder. The only way these results make sense to me is that your grinder is producing doses that vary in grind size/grind size distribution at the same grind dial setting. There are a few possible causes of this variability. The burr holder adjustment (usually under spring tension) is loose and or poorly aligned, so that it doesn't maintain consistent burr spacing. If only the burrs are misaligned, that would result in a wide grind size distribution at any setting, but I'd expect that distribution to be consistent from one grind to the next at the same grind setting and I'm not sure why mixing six doses would improve anything. This points more toward a problem causing some sort of cyclic drift in the burr spacing between doses.

This is why I suggested doing a sift analysis of grind distribution using graded Kruve sifters.

Working with Clive Coffee's "concierge." What a quality organization they are! They had me send some pics of the burrs and did some live videos and took seriously my detailed notes and concluded there's something not right about the burrs. They offered to send me new burrs, but gave me the option of trying a different grinder. Gonna send me a Sette 270 which is huge on sale right now. ≈$200 cheaper than the Silenzio.