Chestnut X not grinding fine enough for La Pavoni?

Grinders are one of the keys to exceptional espresso. Discuss them here.
SKILL_POLICE

#1: Post by SKILL_POLICE »

Hello there!

Its my first post, so i might as well introduce myself - im new to the world of espresso, and just finished completing my equipment. I've been playing for about 2 weeks and i was generally happy with my results. But!

I bought a chestnut X from timemore, and i am not sure if it can grind fine enough for LP. I was using it on 3.2-2.8/25 and the espresso from LP was very fine. I had good extraction times and was able to do 7-9 bars of pressure since i have the pressure sensor. I'm usually packing 14 grams, and try to aim for around 20s extraction, 7s preinfusion. The whole extraction process felt... right, and the resulting coffee was very nice.

But i've read in the manual to absolutely not use the grinder at settings from 0-3, as damage can occur. And in fact, i can hear the burrs slightly grinding against each other on setting 3, so i tried something above that. Buuut, higher settings like 4 dont really provide coffee fine enough, and i can press the lever and feel much less resistance and in effect i have a much much faster pull.

What should i do about it? Can i do something about it? Is the chestnut X unsuitable for LP, or am i doing something wrong? Perhaps i have already damaged my burrs, as i was using it in setting 3 for about a week. I might be doing something wrong, since they recommend 4 for turkish coffee, and 5-9 is espresso range, but this does not give enough resistance to do a 20s pull at 7-9 bars. The coffee just... flows out.

Should i compensate by trying to dose higher? I could try to go around 3.2 (since its not in the manual specified danger zone, heh) and dose a bit higher, but that means that i will be doing things right at the very end of usable range, and it does not feel right. With other coffee the 3.2 might not be enough of a grind, no? And in fact, the burrs do slightly grind against each other at 4 as well, so i suppose some damage might be occuring anyway. I should add that my current coffee was roasted around 3 months ago, so perhaps this is why i need a grind so fine.

ojt

#2: Post by ojt »

I don't know the grinder in question but generally speaking it sounds like bad alignment of the burrs. On my Kinu I can go almost burr lock with no rubbing.

The usual hallmark sign of bad alignment I have seen is that you have a very thin margin of grind settings where one setting would choke the machine and slightly coarser would give a gusher. Whereas with a well aligned grinder you can tweak the grind by quite a lot in any direction.

If you can, if it's possible with your grinder, try and tweak and align the burrs a bit yourself. If not then all I can recommend is consider a better grinder..
Osku

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SKILL_POLICE (original poster)

#3: Post by SKILL_POLICE (original poster) »

I am not able to "choke" my LP on any setting (Well, i have not tried 2, 1, or 0, since the manual forbids them). But yes, the differences between 4 and 3 grind settings are big when it comes to attainable pressures and extraction times. I thought it was kind of normal, as its my first "professional" grinder.

Would be a shame if the grinder was unsuitable for LP, as i paid around 300$ for it, and it was meant to be better than commandante.

So, its not normal for grinder to be "way too coarse" at 4/25 and "just right" at 3/25? I have to say i am very happy with how it grinds at 3/25, its just that the manual forbids me from doing so...

I have no clue if i can realign the burrs on this thing manually.

ojt

#4: Post by ojt »

OK so I had a look and it seems you should have these "secondary" clicks, 5 between each number, so that should give you some more adjustability.

Now still, if 3/25 is not enough you really don't have much to play with when going for very light roasts for example. Kind of sounds like a pour over focused grinder even though they do seem to market it as espresso capable. If what they say about very small amount of fines then that could also affect the brew times. As we know the so called EKspresso is faster flowing than the traditional, and this does not play well with the Pavoni with which you need to grind fine and have a very limited total output.

Can't say if you have picked the wrong grinder, you need to figure that out or find someone who has tried the same combo, but it does sure sound like you would want to grind finer.
Osku

SKILL_POLICE (original poster)

#5: Post by SKILL_POLICE (original poster) »

Alright, it just looks like it might not be monotonic, because it seems like 4 -0.6 actually seems finer than 3.0. Since on this grinder you select a major number, and then subtract a fraction with secondary adjustment dial. And this setting seems to provide very nice espresso setting. Still, i feel like im dancing on the end of a range here, but eh. Perhaps my burrs really got misaligned, i should try to read up about how to diagnose and fix it.

At least i can enjoy a nice coffee without going into the manual's "danger zone", but im not sure it really changes anything, since im still getting a bit of burr touch.

Jonk

#6: Post by Jonk »

Also make sure that the nut on top is tight at 0 - if it's anything like Timemore's other grinders it tends to become loose after some grinding.. A flaw in the design. The result is that for example 3 could easily be 7 "real" steps.

On some of their grinders the ring burr is not fixed properly either, so it will move and rub when the grinder is empty at fine settings. My guess is that it's not a big problem when there's beans to lubricate and apply pressure in all directions inside the grinder - look at how Comandante and basic grinders like Hario Skerton works. There will be some light rub but probably not enough to do any real damage to the burrs (my G1 is still sharp and in good condition after a couple of years)

Jeff
Team HB

#7: Post by Jeff »

Non-monotonic doesn't sound good, especially combined with the other symptoms.

Edit: See post above for a potential solution before working with the seller.

Have you talked with the seller? Are you within the right of return period?

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Jonk

#8: Post by Jonk »

I forgot to note that I have mostly ground for aeropress or coarser with my G1, so it might not be indicative of how a grinder that is mostly used for espresso would fare.

ojt

#9: Post by ojt »

There is maybe the chance that you're actually grinding too fine but with poor puck prep you get some channeling and that "balances" the overall brew time to the standard, or that the initial jet of water from between the piston and the inlet hole in the grouphead creates a crater on your puck. Have you inspected how the puck looks like after a brew?

You could do a test. Grind at setting 4, do your absolute best in puck prep. Try and distribute the coffee so that the bed is even before tamping. Then tamp (and the tamper is a fairly tight fit?). Now place a disc of wet / rinsed coffee filter paper on top of the coffee bed. Cut it to be just a little too wide in diameter. Lock in and brew. See how it goes.

Also brew temperature is important. The grouphead should be stable at perhaps somewhere around 85°C or so, depending a bit on which model you have.
Osku

SKILL_POLICE (original poster)

#10: Post by SKILL_POLICE (original poster) »

After some more testing it seems that 3 is in fact slightly finer than 3.4, i think. Its hard to feel it with a lever machine sometimes. :D So, i hope we are in the realm of monotonicity!

But, I did what you specified and tried going to zero straight. I can go like half a click past 0, but nothing more. So, i cant touch 25 through zero, but im close. Is this acceptable? If not, how do i fix it?

I'm after my return period, so i suppose it would be great to know what can i do to make this grinder good. I suppose i could send a line to manufacturer asking about on what setting is light burr rub acceptable according to spec.

As for channeling - for most of my shots i dont observe any obvious channels or side channels. Channels happen to me when i'm lazy with puck prep or when espresso gods just decide so, but im not talking about channeled shots. You can definitely feel when channels happen on a lever, as there is a sudden drop of force needed to maintain pressure and things start flowing way more violently.

I have a thermometer attached to group head so im usually pulling when its around 85C. To avoid disrupting the puck i usually pull the lever upwards almost to the point where water flows and only then lock in the portafilter, to avoid sucking air through puck. The tamper i use is 51mm and the basket is 51.6mm i think, but it seems okay.