Another factor is that there are grinders that simply cannot be used without a bean load above the burrs; two prime examples from my own experience are the Cimbali Junior/Cadet and Max models.

I have a Junior and DRM/Cimbali that are pretty much the same hopper design. A while back I made this piston to get rid of the hoppers. It's always worked very well, without the waste that used to get stuck in all the little places in these grinders.

another_jim wrote:I got less, about 5 seconds difference, but still enough to require a setting change when switching between the two methods. However, I put my single dose beans into a cylinder and weight it with a piston, so the early part of my grinding may approximate the weighted process.

I was also surprised at the magnitude of the difference, although Dave had mentioned "blond gushers" in past posts. I know I'll be more careful about letting my (mini)hopper run dry in the future...

another_jim wrote:I'll be very curious to see what the particle analysis shows on this. My only idea to explanation the finer grind required when beans popcorn is fewer fines. I known fewer fines leads also leads to longer dwell times for an overall equal pour, so that is an alternative way to check it.

My intuition tells me that popcorning is likely to generate more fines, together with a wider spread of particle sizes. More fines does not explain the faster flow rates, but perhaps the uneven larger particles do not pack as well, or are more permeable, allowing water to flow through the puck more rapidly.

On a related note: after examining preliminary SEM images, I postulated that conical grinders, due to the longer grinding path, may generate smoother, more regularly shaped particles, together with more fines. These particles might pack better, producing more even flows and more forgiving pours.

Unfortunately all of this is post hoc analysis. As you note, fewer fines from popcorning would neatly explain the faster pours. Interesting grounds for speculation, and a clear call for future study.

A question for you guys using dosers and dosing/grinding per shot-

Do you clear out the grind path (between the burrs and the doser) and use those grinds as well? Or do you just use what falls into the doser?

It would seem that the last grinds to exit the burrs would be the ones most affected by the presence or lack of weight above them...

Henry (enjoying the ongoing discussion!)

another_jim wrote:I always clean the chute, pulse the grinder, and clean the chute again. This leaves the grind chamber empty of anything except the compacted coffee. If you have beans in the hopper, you can still clean the chute if you want, but you can't pulse the grinder.

As do I. I clean the chute after the grind when doing a single dose. When the hopper is full, I clean it before my next shot and run a two second pulse to clear out the old stuff.

RapidCoffee wrote:I was also surprised at the magnitude of the difference, although Dave had mentioned "blond gushers" in past posts. I know I'll be more careful about letting my (mini)hopper run dry in the future...

I have not noticed the same thing on a flat burr grinder. I have a Cimbali Jr. and Mazzer Mini and do not recall having a similar issue although I may have and just never paid it any attention. The Kony was the first time I had noticed it. I will put a few doses of beans in the Jr, adjust it in and see if the timing changes as the beans disappear over the day.

another_jim wrote:If you have beans in the hopper, you can still clean the chute if you want, but you can't pulse the grinder.

Ehm, you could close the gate in the hopper when you're done with the dose and let that run through, but that would be a huge waste of coffee. The Major allows enough coffee for two 18 to 20 gram doses under that gate.

I usually pack two, and sometimes three, doses in depending on how many folks I'm making coffee for at any given moment. If there were a disparity between the quality of the grind with a dose on top, or two doses on top, and none on top, wouldn't the pulls be significantly different? I'm noticing that one, two, and three tend to be remarkably the same in appearance and taste, regardless of the amount of beans on top of them when they're ground. OTOH, two doses bearing down on the first may not be enough to make a difference.

hbuchtel wrote:Do you clear out the grind path (between the burrs and the doser) and use those grinds as well? Or do you just use what falls into the doser?

Chute is always swept clean; grounds are used if needed for that session. My Super Jolly doserless mod makes chute access trivial:


zero grounds left behind in the chute

That could be why I saw such a big effect on flow rate...