I hate when people start throwing around "retention" numbers with no explanation of how they were calculated. Is that the amount of coffee left inside if you sweep everything out of the grind chamber and chute, then grind through a single dose with no further sweeping? Or is is the amount you get out if you remove everything above the burrs down to the little broken bits of beans, grind everything through, and sweep it all out? Only the latter is a useful figure when determining how much you have waste at the beginning of a session to get to the fresh, unground beans when using a hopper.

I realize there has been a fair bit of discussion on this subject in the past. My concern is more for when when people start throwing around numbers in threads like this, e.g. "4 grams" for the K10 Fresh. It's not useful information without further qualification.

I think if you are using a grinder with a hopper, the only useful "retention" figure is what I described in my second example, taking into account the heavily broken beans stuck in the burrs, the coffee in the grind chamber, and what is trapped in the chute. This is how you arrive at the traditional 10 gram figure for grinders like the K10 WBC/Pro Barista. Brushing out the chute can cut it down by a few grams, but this is usually less practical with a doserless grinder.

I would like to know how the 4 gram figure I keep seeing for the K10 Fresh was ascertained. With my K10 WBC, single dosing with a completely clean chamber, I lose about 6.5 grams. A quick brush of the easily accessible chute gets another 3-3.5 grams out, leaving 3 grams inside that can be completely removed with further bumping and brushing. I find it hard to believe that the sum total of everything the K10 Fresh holds in its burrs, grinding chamber, and inaccessible areas of the chute when using a hopper is only 4 grams. I also don't think most users are going to be sticking a brush up the chute all the time.

Hi,

A post I wrote was quoted a bit earlier. I came up with a 4g retention figure by running the grinder until coffee stopped coming out. Then I brushed out the chute, and vacuumed with my powerful little Dyson.

Next I weighed out 20 grams of beans, ran them through the grinder, and weighed the results. If I remember correctly, I tried a couple different times with different bean masses, and always came out around 4g stuck in the chute.

I didn't read the post that was referred to in this thread regarding the recommended methodology, but this seemed like a common-sense approach to me -- correct me if I'm wrong.

Frank

I have a portable dyson and it was never capable of clearing the coffee retention from my Macap M7D. However a small soft Le Creuset silicone (kitchen stores/Surlatable) measuring cup did. By turning it upside down over the grind chamber and pumping it the grinds would literally fly out the shoot. Pump, turn on the grinder and do this routine and it removes the grinds locked inside very efficiently.

Not very elegant but effective. Might be a hassle if the hopper has to be removed. I never used the hopper.

Bob_McBob wrote:I hate when people start throwing around "retention" numbers with no explanation of how they were calculated. Is that the amount of coffee left inside if you sweep everything out of the grind chamber and chute, then grind through a single dose with no further sweeping? Or is is the amount you get out if you remove everything above the burrs down to the little broken bits of beans, grind everything through, and sweep it all out? Only the latter is a useful figure when determining how much you have waste at the beginning of a session to get to the fresh, unground beans when using a hopper.

Sorry for disturb you, I just tried to help.

Not exact numbers on my last post though; I took the measurements some time ago. Let me post some numbers that I had noted in a notebook.

Chute retention: 1.73g
Burr Chamber: 5.70g

This is the amount of coffee retained after grind all the coffee remained in the hopper. To measure, I opened the grinder and I took all coffee from the burr chamber and the chute. Be aware that I usually remove with a large spoon some coffee retained in the flap. The "chute retention" refers to the amount of coffee that I can't remove from the outside with the spoon.

shadowfax wrote:A pretty good estimate on a doserless grinder would be to clean it out relatively well and then load up 75 grams of coffee and grind through it and see how much you get back. This will probably underestimate retention a little.

Load 75g of coffee with a completely clean burr chamber & chute gives 70.7g out.
A second load of 75g gives 72.4g
A third load gives 72.0g

shadowfax wrote:I think the real crux is the anti-static flap. We need a documented disassembly or blown up parts diagram, I think, to really know.

Yes. As I said there is a flap, which of course can be removed as is attached with 1 screw. This should minimize the retention a little. Sorry, I have no measurements of this.

Has anyone else purchased the K8 or K10 Fresh? I was wondering how others were attempting to fit it on top of their counters and under the cabinets, utilizing the short hopper? 20" high is a tight fit under most cabinets. Has anyone tried modifying the height (removing feet if it has any, etc.) to squeeze it under the cabinet? By looking at the pictures of it, I'm not sure if anything can be done to shave some height off of it, other than trimming the hopper. Any comments appreciated.

Thanks