I am doing a talk on grinders at the LA Coffeecon, and discovered something while going through my notes: the percent extraction change for every gram of dose change (with counteracting grind setting change to keep the flow rate the same) is much larger for flat burr grinders than for conical burrs. The evidence is pretty slim, but it also accords with the way the particle distributions probably change for flats (more coarse particle changes) versus conicals (more fines changes).



This needs to be confirmed with more experiments. But if this is correct, then the practice of conical users of making dose changes of 1 to 2 grams at a time to modulate extraction needs to be damped down a few notches when using a flat burr. Flat burr users should try 1/2 to 1 gram dose changes to get the extraction levels right, and make their grind adjustments accordingly.

Thanks for sharing this info Jim, I already started to wonder about 1-2 g of difference ...2 g fis not something the faemina has the space to accommodate for to begin with but lately I also thought that my experimenting showed that smaller changes have quite an effect but I was not sure whether it was an effect of the faemina or the grinder.
Am curious about the results of further experiments, it sounds about right to me...

Very interesting.

1. It's curious how TDS drops off with flats. Suggests grind inconstancy with larger doses, which doesn't make any sense. Must be something else going on. Burr alignment?

2. Your graphs echo's what many M3 vs large conical owners have found (IE: HG1 vs M3): That shots from the M3 to be more soft/mellow in taste compared to conicals (less TDS).

This observed ratio is in close agreement with my experience owning a Versalab and an HG-1. I habitually time and weigh all shots. Flow rates are about half as dose sensitive on the HG-1.

I'm glad people can confirm. IMO, using dose and grind changes is the most direct and certain way of improving extraction and shot quality; so it's saves a lot of frustration knowing the magnitude of change each style of grinder needs to use.

Was this experiment done while single dosing the large conical grinders or with beans in the hopper? I have done tons of side by side experiments with my M3 and my compak k10 and I feel beans have to be in hopper on K10 to create a level playing field.

UFGators wrote:Was this experiment done while single dosing the large conical grinders or with beans in the hopper?

Both, but neither very extensively -- it was part of the TGP I rediscovered in my notes recently

Also, The single doe versus hopper may be the most pointless discussion ever. First off, if you use several coffees, you have to single dose; and if you use one at a time, the hopper is more convenient, so which one you use is not a choice. Second, while there are grind adjustment differences between single and hopper dosing; there are no consistent blind tasting differences, nor size differences that a laser counter can catch. No choice, no taste difference, no size difference; so why discuss?

Because of Ben Kaminsky and his consulting. That's a major reason why. Sorry that's sounds cynical. I don't mean it to be. But why is it that you report no discernible differences and Ben says you need at least 1 kilogram above the beans?

I'm not tasting any difference going between using a weight above my beans and no weight with the k10 while single dosing. If I did I would have stuck to using a weight.

Spitz.me wrote:I'm not tasting any difference going between using a weight above my beans and no weight with the k10 while single dosing. If I did I would have stuck to using a weight.

Interesting that the K10 is so much different to the Nino.
When I was single dosing with the Nino I could not get close to the extraction yield vs filled hopper.
The blonding came much earlier and there was also a big difference by taste of course, otherwise I wouldn't be bothered and go for the single dose and brushing routine, it did not work for me.

I've been through most of the bean feed options with my K10. Small Compak hopper(K6?) filled, feeding the beans directly into the throat/weighting with a spice jar & using the OE Mini Hopper with no weight, just a tamper sitting in the top. Outside of each method requiring a slightly different grind setting I didn't see or taste any difference. The grounds still come out uniform & fluffy with any of the options & no further distribution (WDT) is required. Just grind, dose, level & tamp.