For the longest time I struggled with getting any result from dialing in my grind. I now dose my basket, level with a round pencil NSEW style, then i have a slightly concave piece of hard plastic and do one pass with that. I then use my autotamp for consistency. I now have a tamped level basket that fits slightly under the screen (a coin fits but no more than that). Once using this method i finally began to see the result of minute adjustments to my grind. However what I am not seeing is what I see in the many videos of shot pulls. My pulls are taking 25-30seconds yes, but lack any sort of rich thick appearance like on the vids. Maybe it is my beans (they are locally roasted about 6 days old kept in a fresh container) I would say the first 5 seconds look gorgeous like the vids then the thin stream goes a bit watery for the last 10 seconds yet the stream is still thin and slow. If i dial my grind any finer it chokes. Is there a technique that will give me the rich thin stream for the full shot? maybe grinding much finer and tamping lighter? Thanks!

Equipment:
domobar super, boiler1 pressure 8.5-9bar with blind filter
mazzer mini grinder
autotamp

Sounds like old beans or some channeling. When you put a blind basket in the portafilter, what is your brew pressure?

cannonfodder wrote:Sounds like old beans or some channeling. When you put a blind basket in the portafilter, what is your brew pressure?

Just checked, Pressure is 9.5 with blind shot but doesn't that equate to 8.5ish on the puck? I've had a lot of frustration setting the pressure on my domobar. For example i opened it up yesterday and had it set to 8.5 with the blind on. All my shots and back flushes yesterday were 8.5, however today it has crept up to 9.5. If I lower it again to 8.5 a few days later it will be down to 7.5. I guess i need to make extremely minute adjustments. I have already confirmed i have the beefy spring (some said to check this spring). I also suspect the beans were bad as well, the last batch i was able to get some quite rich shots but this same brand and all i can muster are bright tasting shots and bad pours. Looks like i'll have to keep seeking out better supplier.

jeffg wrote:I would say the first 5 seconds look gorgeous like the vids then the thin stream goes a bit watery for the last 10 seconds yet the stream is still thin and slow. If i dial my grind any finer it chokes. Is there a technique that will give me the rich thin stream for the full shot? maybe grinding much finer and tamping lighter?

I'll go with Dave's diagnosis: Not so fresh beans, or channeling. How much coffee? The Domobar prefers lower doses, i.e., just below the ridge of the basket.

jeffg wrote:I've had a lot of frustration setting the pressure on my domobar. For example i opened it up yesterday and had it set to 8.5 with the blind on. All my shots and back flushes yesterday were 8.5, however today it has crept up to 9.5. If I lower it again to 8.5 a few days later it will be down to 7.5.

...I have already confirmed i have the beefy spring (some said to check this spring).

For those who are following along, Randy's explanation of the heavier OPV spring:

Randy G. wrote:
The new spring, on the left, is much heavier than the original that I removed. The difference can be seen here, and compressing them between index finger and thumb reveals a great difference in compression force as well, with the new one being far stiffer.

Replacement is a simple matter of unscrewing and removing the adjustment screw, removing the old spring with a small tweezer, and replacing it with the new spring. Screw in the adjuster and Vito's your barista (Bob's your uncle?).

Once I had it all back together I inserted the blind filter and readjusted the OPV. I found that the new spring made it MUCH easier to adjust. The original was very touchy and the smallest adjustment made a large difference. The new spring was very linear in its adjustment and finding the desired setting was a very easy matter. before closing it up I turned the pump on and off a few times and every time the pressure gauge hit the exact pressure I had set.

jeffg wrote:I also suspect the beans were bad as well, the last batch i was able to get some quite rich shots but this same brand and all i can muster are bright tasting shots and bad pours. Looks like i'll have to keep seeking out better supplier.

Did the grind setting change between the "rich shots" and the bad pours? If the latter grind setting was significantly finer (2 or more notches on a Mazzer Mini), the coffee is probably stale. The brew pressure wandering can't be helping things either...

Hi Jeff,

Just off the top of my head, the problem could be:

(a) Coffee: To check, you might want to try out something that you know will work. Try looking for a blend with a good whack of malabar or robusta in it; if it is properly aged, it should deliver very rich pours. You might or might not like the taste, but the point of the exercise is to eliminate coffee as a variable by using a blend that you know ought to pour nice and richly. If you're in Sydney, ECA were getting some rich pours from Toby's Wooloomoolloo blend at the Aroma festival.

(b) Dose: Try more coffee and a coarser grind. Don't worry about the whole headspace thing - worst case scenario, you screw up a few shots and then backflush. If dosing proves to be problematic, you might need to try a bigger basket.

(c) Brew pressure: Perhaps your gauge is out of whack?

Cheers,

Luca

jeffg wrote:I also suspect the beans were bad as well, the last batch i was able to get some quite rich shots but this same brand and all i can muster are bright tasting shots and bad pours. Looks like i'll have to keep seeking out better supplier.

We should also separate looks from taste. I assume by bright (?) you mean sour, i.e., underextracted due to channeling.

Hi guys, hold off on the suggestions for now because I now have a cafe owner/barista (5 miles from me) coming over for a training session in 1hr!

Even better he sells domobar supers. Here is hoping he can tune up my machine pull some great shots then teach me how to do the same. Fingers crossed!

I'm in shock.. The guy came over and in 45mins we're pulling dream shots. He's an old chap probably been drinking and making espresso longer than I've been alive. He just had an intuitive way of dialing my setup in and it's all much more simple than what I had been doing to boot. Things clicked very fast by watching him and listening to his critiques of the taste as we progressed. I did 3 doubles in a row that were downright delicious. All in all his method seemed to be grind to suit the autotamp and extraction time to suit the coffee. What this amounted to was an 18sec shot time from the moment the pour begins. For dosing it was just fill the basket slightly over the lip then scrape the excess off with the lid to the mazzer doser, tamp, pull when the temp was right. The head of crema was out of sight dang should have taken some pics but was too caught up in the moment. I'm in much better spirits now. Even better he lives 2 blocks away

Experience is a good teacher, eh? Assuming you can duplicate his results, I am interested in the diagnosis of the problem. Our guesses were all over the map.