another_jim wrote:I don't start timing until I see the first drop -- that takes care of all the ramp up stuff.

The reason I went to this is as I dropped the dose in my experiments, keeping the flow characteristics (after a drop appeared) about the same, the dwell time got longer longer and longer. At 19.5 in the triple, I averaged around 4 seconds, at 12 grams I averaged around 8 seconds.

RapidCoffee wrote:Argh. I would have predicted just the opposite. Is this due to faster pressure ramp up with larger dose?

another_jim wrote:I got roughly linear changes too when I systematically changed dose and adjusted the grinder for similar timed shots.

another_jim wrote:I also think it is simply finer grind.

another_jim wrote:I haven't figured this out yet, and I haven't posted the data before. It is a solid fact; I've observed it countless times in regular shot making. None of the doses I charted touched the shower screen, so that's not part of the effect.

I also think it is simply finer grind. My hypothesis (until someone tells me something different) is that the flow is determined only by the amount of fines. A lower dose requires a disproportionally finer grind to produce the same number of fines, and that should mean the water gets through the puck more slowly.

The alternative is that it's simply a question of filling up more headspace over the puck. If someone will give me set of baskets, identical except for depth, I'll test which one it is.