I think Jake's point is that when blooming ends (whatever 'bloom' means), one wants there to be no air and no dry coffee in the puck. (Or at least an evanescing number of dry spots in the puck). So at that point the extraction will be most homogenic from all parts of the puck. Jake -

So for my machine the number I plan for is 28ml. This is measured by my flow meter (a digmesa) which I calibrated to different flow rates (but I cannot state a certainty figure for so take with a grain of salt). The number did not seem out of place as according to coffee tools: Bev weight 36 grams

Since the Duvall limits the available water debit I expect it to be as forgiving as a gear pump (Slayer, Strada), levers, correctly dosed e61 and wide range paddles (GS3 MP, Lelit, JakeOne). So I don't expect better puck prep. Just a higher percentage of good shots. Obviously, since the debit can (p...

My observation is that PI on a 18gr dose is when 28ml water has passed into the puck. Obviously the time it would take depends on volumetric pump speed/debit/lever piston depression. PI timing may not be important as long as the puck drinks up the PI volume. To get it to fill up one may have a minimum

No - if there were hysteresis issues I wouldn't have purchased the 70$ OTTO control (well spent in hindsight). With PWM the pressure and flow are spot on and really responsive. The hysteresis is with the old gicar flowmeter and its low pulse rate with PID (did not work to test it much with the new D...

... is bad (bad 3w! Bad 3w!) I've been roasting a wee bit darker. (Drop temp between 210-215). And grinding coarser. So now I do a wall PI (try to get 28ml into the puck rather quickly), pause, and pulll between 6-9bar (6 being Ctrl

... now mostly emulate a GS/3 MP. For the longest time the Slayer method was preferred until I realized that the PI volume was key. So at an 18gr dose 28ml are always the exact point drops appear. Consistent to +- 1ml (perhaps less). The Digmesa is indeed accurate... For darker roasts a step function ...