Help with divots in puck

[UFGators]

I just recently noticed that when I get a proper length shot there are two small holes on top of the puck where it appears that either the preinfusion or the main infusion of the puck has blasted holes in it. I am running a 25 psi 3 sec preinfusion and slightly under 9 bars for the brew pressure. Any ideas? I am dosing around 18 grams so that the puck is just below the ridge line before brewing.

[oton]

2 holes?

When you are brewing the puck needs to expand, so its possible (sure with 18gr) that the puck touch the shower and the bolt, hence the divots. Try downdosing.

[michael]

you can get 18gs in a standard double basket?

i do my doubles at 15gs plus a bit for the part that gets left in the mazzer e; i can get 19-20gs in a triple basket

i thought the idea was not to have a big mark on the puck from the nut

[JohnB]

Sounds like channeling but the real question is: How did the shots taste?
For thoughts on Puckology: http://www.home-barista.com/knockbox/pu ... 10517.html

[michael]

for me, i find that generally the minor flaws in the puck do not affect taste

[Endo]

Have you tried the obvious? Removing both screens and diffuser and giving eveything a good cleaning?

What does the flow look like from the screens when you remove the PF?

Can you post a picture of the puck surface so we can compare?

[UFGators]

I will take some pictures tomorrow morning of the pucks, I did clean the screens a couple of days ago and the flow from the screens seems to be pretty even. Is it possible that I am tamping too hard if I need 18 grams of coffee to get the coffee to be just under the ridge level after tamping? I have tried down dosing but I seem to get major early blonding when I do this. Any suggestions? The shots taste pretty good despite the defects but they are a bit unpredictable. I have an espro tamper to check how hard I am tamping but I cant seem to get good results when I tamp only at the pressure required to depress the tamper.

[JohnB]

The Vivaldi's strong suit is not large doses & the larger the dose the better your distribution needs to be. When you use a smaller dose you will have to grind slightly finer then you did for the larger dose otherwise you will get the early blonding. Try using 15-16g doses instead of 18g & you will get much clearer flavor characteristics in the cup. Personally I prefer 14g doses for S/O & 15-16g doses for blends. If you want to use larger doses get a triple basket so you have some headroom left after adding your grounds but all you gain with the big dose is more caffeine & a muddier shot.

[Endo]

Another obvious warning, but maybe it needs repeating here. Coffee type and freshness (less than 2 weeks old) make a huge difference on the Vivaldi and especially when using smaller doses. This may be causing the problems you have been having with smaller doses.

The divots, I believe, are the result of head design of the Vivaldi. Since it doesn't use a dispersion screw but rather a direct "showerhead" just millimeters above the puck, the flow rate is much higher through some holes (you can easily see this). Once the headspace fills up with water, the divot effect on the surface of the puck is probably reduced.

On the E-61 (and most other machines), they use a dispersion dispersion screw to avoid impinging the jets onto the grounds and also the space beteeen the jet and screen is much larger (almost like having extra headspace). The result is the water comes out much more evenly from the screen. Does it affect flavor? Who knows.

[JohnB]

You would think that if his divots were the result of the supposedly inferior L/S head design we'd all be seeing them.

[Endo]

You would think that if his divots were the result of the supposedly inferior L/S head design we'd all be seeing them.

I saw them a few times as well when I dosed high. I think it might also have a luck component based on how the outer screen lines up with the diffuser holes.

You definitely right about the 15g sweetspot. I think it's related mostly to headspace.

[UFGators]

Why do you think I am having a harder time with the smaller doses? Probably not grinding finely enough? I feel that if I use a smaller dose after I tamp there is too much space between the screen and the puck which seems to lead to major channeling. Should I try grinding finer, dosing less, and tamping less? My coffee is never older than 2 weeks and never brewed before 5-6 days of resting after roast date. Man, who knew that espresso was this challenging! I thought that after I sold my silvia I would be getting much more consistent results but here 2 months later and I am still figuring out my machine!

[UFGators]

Well, my experiment this morning proved successful. I turned my mazzer mini E down one notch finer and weighed my dose to 16grams. I am used to overfilling the basket then leveling it off to get the proper dose, but this fills the basket with too much coffee. I used a crooked finger approach to distribute the coffee that did not come up to the rim and then I used a lighter than usual tamp (I think I tamp harder than I think). The results? My espresso came out at the perfect extraction time for me which was 28-30 secs including the 3 sec preinfusion and the color was perfect! I even had more crema than before. When I unlocked the portafilter after brewing the puck had no cracks along the outside and only a faint screw inprint on top. One thing I did notice was my puck was much more soupy and fell apart when I knocked it out. I tried to correct this by dosing one more gram (17) and tamping harder. After I did this I noticed earlier blonding than before! Does it make sense that this machine likes smaller doses but one must have to be careful not to tamp down too hard to give the machine too much headspace above the puck? I hate a soupy puck but I cant argue with the results or the taste. I would appreciate the feedback.

[JohnB]

You are worrying way too much about the puck! Who cares if the puck was soupy or not as long as the shot tasted good. I get some soupy ones & some dry ones, big deal. The only thing that matters is how the shot tastes! Don't be afraid to down dose as "too much headspace" is an imagined issue. Also don't feel that every shot has to fit within a certain time frame. I get some delicious shots that run 35-40 seconds & I don't start timing until the pump kicks in. Try some 14g shots with no p/i. These are my favorites when using S/O espresso.

[Endo]

Why do you think I am having a harder time with the smaller doses? Probably not grinding finely enough? I feel that if I use a smaller dose after I tamp there is too much space between the screen and the puck which seems to lead to major channeling. Should I try grinding finer, dosing less, and tamping less? My coffee is never older than 2 weeks and never brewed before 5-6 days of resting after roast date. Man, who knew that espresso was this challenging! I thought that after I sold my silvia I would be getting much more consistent results but here 2 months later and I am still figuring out my machine!

Don't get discouraged. I went through the same frustrating stage for the first few months. All I can say is that eventually you will find a technique that works. After that, it becomes VERY consistant.

For me, this is what worked.

1- Coffee (no more than 2 weeks old).
2- Grind (the factory setting mark on my Mazzer).
3- Dose(15.5 g for me, mostly I measure volume by seting tamper base height level with basket rim).
4- Distribution (no clumps, one tap on the table to settle, then distributed with a bent finger to fill in the edges).
5- Tamp (2 stage, first lightly with a slight nutation, second time with 20 lbs and a twist polish).

But be warned....month #3 usually involves buying a bottomless PF and then you're into another round of frustration.

Month #4 seems to be dominated by steaming issues! (The hardest of all to solve IMO)

I agree the Silvia was MUCH easier, but I think this mostly because I've come to expect a lot more.

[nitpick]

I posted another article along these lines but I also routinely get/got a divot in the puck with my VII.


I upped my line pressure from 2BAR to 3BAR, however, and the divots all but disappeared. I am using 4 seconds of preinfusion, FYI.