So, it seems that I'm getting donuts regardless of blend, tamper profile, grind, distribution technique, day of the week, etc.

Could it be my porta filter prep? I have a habit of cleaning out the basket after I knock the puck into the box. The last thing I do after pulling a shot is flush the group, and clean the basket. Every shot I make is made with a clean. dry basket.

OK, here are the rest of the details. I grind right into the basket, and leave the handle in the group until I'm ready to tamp. I thwack while grinding (a Mazzer Major) twenty-ish grams into an eighteen gram basket (clean and dry) with a yoghurt cup keeping the grounds from going everywhere. I WDT, and then Stockfleth, and then modified Stockfleths with the dissecting needle handle (Thanks John!) I gently place the basket in the bottomless PF handle (light gauge spring) and then NSEW, tamp to 30 lbs. clean the edge, flush the HX, lock in and pull for 27 seconds. It always gets me a donut, and I can tell how long the shot'll run by how long it takes the donut to close up. A decent shot will take five to seven seconds to close up into a cone, and anything shorter than that will get me two ounces in less than twenty seconds. Changing the tamper to an American curve doesn't seem to change much, and anything that runs toward ristretto at all tend to give me spritzers.
I've got the best tools (CMA's Astoria Argenta SAE-II and Mazzer Major) I could ask for, and the best teachers espresso craft has to offer (y'all) and yet, I have this embarrassing secret. Any idea as to what direction to take? I've tried not WDT, not Stockflething, not updosing, updosing, grinding finer, coarser, different roasts and beans and blends, and I get the donut every time.
Questions? Answers? Anyone?

How sure are you on the twenty-ish grams?

FWIW, If I WDT and then level cut or maybe slightly Chicago chop (with the dissecting needle handle, Thanks John!), I get 20 grams in an 18 gram basket. It sounds like you might be working it up a bit higher.

Also, have you tried dropping the Stockfleth's business?

If you're up for experimenting, try just a light weight of tamp and twist (to make sure you are level), and a single firm tamp after that. I would think with Majors, you could forego a lot of the home-barista distribution and tamp rituals and simplify the shot building process.

I am experiencing the same donut of doom! I am seeking and answer as well, but one of my possible solutions, Is a convex tamper (gasp!) I went to a roastery last week, and the tamper that one of the staff had was convex, he said it helped for a more even packing, and it seemed to get good naked extractions, sans donut!

Im sure theres another way though, im just not entirely sure... anymore pearls of wisdom out there?

Donut extractions are channeling along the sides or center-weighted dosing creating a denser center... so what might cause this unevenness?

• Have you checked the brew pressure? Try lowering it 0.5 bar to see if the extraction evens out.
• The grouphead design / brew pressure ramp can exaggerate problems. For example, a center screw and tight puck to dispersion screen clearance can cause the middle of the puck to offer lots of resistance. Tighten the grind and lower the dose by 1.5 grams (or a good 2mm of clearance).
• If your machine is a rotary and the water jet breaker isn't spreading the water out nicely, prolonged preinfusion or smaller gicleur might help. Try Ken's preinfusion puck examination to see if the puck is getting uneven wetting (below).

From How to Preinfuse; Extraction Pressure Redux

A lower dose and a convex tamper should help. Adjust your grind towards a slightly faster flow rate at first, then tighten it up.

I've got an "18g" ridgeless double that is really a triple. Is that what you're using? I've always found it harder to get really even pours from a triple. If all else fails, try a smaller basket. 20g is on the high side for a double.

HB wrote:

• If your machine is a rotary and the water jet breaker isn't spreading the water out nicely, prolonged preinfusion or smaller gicleur might help. Try Ken's preinfusion puck examination to see if the puck is getting uneven wetting (below).

<image>
From How to Preinfuse; Extraction Pressure Redux

I resemble that puck . . . .

In all fairness, and giving credit where it was due, this particular experiment in "puckology" was in fact the idea of one James Schulman . . . .

ken

I'm not sure if you' re using the Astoria or the Silvia. Personally, I can't even get a decent tasting shot out of a Silvia if the puck hits the screen (hitting the very low screw is OK). Certainly, donut problems are almost inevitable when the puck is squeezed up against the screen. I'm not sure how the Astoria reacts to this, some machines do it with aplomb, E61 groups for instance, others cannot tolerate it -- the Elektra also donuts and makes terrible shots when the puck hits the screen.

FWIW when I changed to lower dose (15-16g) / finer grinds / lighter tamps (~15lbs) a couple of months back almost all my extraction problems disappeared in one go.

To do this in a Silvia basket I grind, WDT, level with a flat edge and tamp, it's quite consistent.

You could also try a gentle nutating tamp, that helped me when I was having donut problems.

Good luck

Thread Title changed at the kind request of my Editor ; >

RapidCoffee wrote:I've got an "18g" ridgeless double that is really a triple. Is that what you're using? I've always found it harder to get really even pours from a triple. If all else fails, try a smaller basket. 20g is on the high side for a double.

That's the toy! I think I'm going to try to use a finer grind and lower dose to see if crowding the screen less is an answer before swapping out gicleurs or attempting to change pre-infusion on the Astoria (there really isn't any). Ironically enough, when I stay at the GF's house, my pulls on the Silvia are spectacular. I'm using an LM styled ridged basket there that I'm dosing to 15g and pulling beautiful shots.
I've tried a nutating tamp, with and without the Stockfleth's, convex and flat, I'm usually within .2 gram when I dose (lots of time spent with a scale in the learning process, and I'm getting a bit of clumping, depending on the bean, even with the Major, Jes. Most of the Home Barista techniques got their inception trying to solve issues like this, but I'll happily drop the lot for a simple technique to get better coffee! I'll try 'dose, tamp, pull' with something a bit tighter and smaller by leveling with a curved implement til I get down the fighting weight, and see what happens.
I'm guessing that the spritzers should solve themselves along the way as well?

Just to see if it helps, try a finer grind and a lighter tamp.

If that has any effect at all, it's probably a dosing density issue.