HB wrote: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).

So I worked my way down to just under 18g (with some at just over 15g) in the 18g ridgeless, and while I'm still getting the occasional spritzers I'm not WDT'ing for the moment, and just dosing, modified Stockfleth, tamping, and pulling, things are looking up a bit. I'm getting fast shots for the moment, and as soon as I can get some more beans in the house, I'll let you know how it goes!

Psyd wrote:So I worked my way down to just under 18g (with some at just over 15g) in the 18g ridgeless, and while I'm still getting the occasional spritzers I'm not WDT'ing for the moment, and just dosing, modified Stockfleth, tamping, and pulling, things are looking up a bit. I'm getting fast shots for the moment, and as soon as I can get some more beans in the house, I'll let you know how it goes!

I took out my 18g ridgeless and yeah, that basket likes a 20g dose. Here's a (really poor quality) video that I made this evening: 25sec naked extraction with Caffe Fresco Ambrosia, ground on a Mazzer SJ, 20g dose in the 18g ridgeless basket, pulled on a Vetrano. I'll tighten up the grind a hair next time, but it tasted good and no donut!

I used the WDT (natch) and leveled with the dissecting needle handle. Stockfleths' circular motion might concentrate more grinds in the center of the basket and contribute to donuts.

[gvideo]http://video.google.com/videoplay?docid=-3226369635814176629[/gvideo]

No offense, but when did you last give your grinder and espresso machine a good cleaning? When I get frustrated with my pours, I figure it's time to open up the SJ and brush out the burrs, and detergent backflush the Vetrano. Sometimes it even helps...

RapidCoffee wrote: Stockfleths' circular motion might concentrate more grinds in the center of the basket and contribute to donuts.

Hmmm... Makes sense. I did similar results with different timings with the finer grind, smaller dose, and tamping to make it run til 27 seconds. I think I'll start trying to updose a hair and tamp normally, and change my distribution a bit.

RapidCoffee wrote:No offense, but when did you last give your grinder and espresso machine a good cleaning?

Its been less than a month since I took the Mazzer down to clean it, and I make sure that there aren't grounds left in the chute or in the hopper. I have the tape mod on the vanes, and sweep out the chute and the hopper fairly spotless.




I tend to clean all the accoutrements every second shot or so (baskets and PF holder) followed by a cleaning flush and a portafilter wiggle. I brush and backflush once every day or two, (three to five shots) and backflush with detergent every coupla months. On a two group with my schedule, this means backflushing each group after around around thirty shots, max.



I thought I was being thorough, if not a bit too enthusiastic.

You know, I've seen something like this happen not too long ago, and it turned out that their shower screen was nearly completely plugged with coffee gunk.

Just a thought.

Uneven water distribution upon initial contact can really effect the flow.

Jasonian wrote:You know, I've seen something like this happen not too long ago, and it turned out that their shower screen was nearly completely plugged with coffee gunk.

Just a thought.

It's worth a shot, but I'm pretty skeptical. Look at the photo, that dispersion screen is pretty clean my brother, and it's been scrubbed fairly regular, backflushed, too, and I take 'em off and soak/scrub 'em fairly frequently. It ain't like it's too big a chore to check, though.
In other news, my shots on the Silvia are gorgeous (of course) and I'm up to just under twenty grams of finer ground coffee with a slightly less that thirty pound tamp. Spritzes and paler shots than I'm used to, but nice auburn shots with decent crema that doesn't dissipate too fast. My technique is grind into the basket, level and distribute with a coupla sweeps of the dissecting tool, tamp, and pull. I may go finer still, but the spritzes are starting to bug me. The donut is still there, but it's gone within a few seconds of the start of the shot. I'm just jealous of those that start all even and nice, I guess.