If you have a naked pf and notice you're getting "donuts," make your grind finer and your tamp lighter.
I have been getting lots of "donut" extractions with my new Vetrano/Macap m4 stepless. That is, there's often a dead spot in the middle.
Tell me where I'm going wrong...
I dose from the grinder into the portafilter until the coffee is heaping up a bit above the rim of the basket.
Then I use a needle for the WDT, fluffing up the grounds and breaking up clumps.
Then I level off the grounds with my finger, not (intentionally) compressing at all.
Do a very light tamp, then clean off the rim of the portafilter.
Then do a 30lb tamp with the Espro.
Flush a few seconds beyond the end of the water dance, then lock in filter and brew.
I'm regularly getting about 1.5-1.75 ounces in 25-30 seconds, but often with that center dead spot.
So what variables should I adjust? Would up-dosing help? If so, how do I do it while still using the WDT? Should I WDT so that coffee is above rim of basket, then tap the portafilter so that the coffee settles down into the handle?
Fullsack recommends a lighter tamp, but I'd prefer to keep the tamp a constant 30lbs and adjust another variable if possible.
Thanks in advance for your advice.