mrgnomer wrote:It works for me

It does seem to work better, rides up less, thanks

EuroNico wrote:Did you machine the tamper yourself?

no. i live in the east, more china stuff here. its not hard to find something with extra mm. tamper, distributor, etc.
on the minus side, lots of stuff are much more expensive.

i'd recommend u measure ur basket and buy something that works for u. u mentioned the basket tapers, so for less dose the smaller tamper might work. i did the tape thingy to fit the basket diameter thingy but doesnt fix donut. also too tight gap might vacuum the puck when u remove the tamper. i found within 0.8~0.12mm to work without fuss.

One more recommendation to measuring the basket inner diameter and getting a snugly fitting tamper.

If you happen to have the OEM plastic tamper, hopefully with one of the ends too large to fit in the basket, you can try to sand it down to fit just perfectly. As a POC project if not else, to try how much it would help.

Since first posting in this thread, I switched to a 57 from 58mm tamper as a trial. [No sacrifice is too great to advance espresso knowledge] When I started this coffee about a month ago, I chose the flat 58 over 57 flat, 58 American and 58.5 C-Flat.





Essentially ZERO difference in the start or flow or volume per time. But the taste is subtley different with a slight reduction in bitterness and increase in caramel.

Coffee is Equator Organic Espresso, a near dark blend: some oil spots and a fair number of divots. Note this is a Sivetz air roasted coffee, so YMMV.

Thanks so much everybody for all your input!
Also CafeIke I really appreciate you trying out a smaller tamper size, that eases a lot of my extraction-based anxiety
I think the only really big difference offered by a perfectly-sized tamper is that it makes it easier to tamp level every time.
While this may be overkill, my girlfriend has access to a micro-miller in her lab, I may ask her to machine me a tamper to the micron at some point if that happens I'll update this post!
In the meantime I'll work on getting the other more important factors right.

EuroNico wrote:I may ask her to machine me a tamper to the micron at some point

My RB C-Flat 58.5 I had made for my Synesso baskets will not fit in all 58mm baskets

That's a good point, thank you. I'll be sure to accurately measure my basket first.

Find a 49.5 mm tamper and fix most of this issue. It will clear the sides of the basket much more cleanly. Another thing tamper wise that helps me seal the edges is a convex tamper. It seems to press towards the edges for a better seal.

As far as doughnut extraction, this is normal for Pavoni's. Blooming shots especially show this. If the edges are all blooming about the same the bloom will then move to the center, this is what you want. If one or more section of rim is going fast, the edges weren't sealed well and it is channeling along that. If you see a middle region dripping early it is either a sign of channeling or your lever raise may have disturbed the puck, or the water burst from the shower screen and channeled it.

Thanks, I've found some ok 49.5 mm tampers, but I'll still probably try milling a 54 mm tamper I already have first as that's free!
A convex tamper is an interesting proposition.
Since initially posting this, I've also "upgraded" my cork WDT tool from having normal needles to .25 mm acupuncture needles, plus my prep, grind setting etc in general is better now. I get the blooming doughnut you describe, and it seems like I mostly get even flow and tasty results with this non-precision tamper