I'm curious to know if any one has thought or, better even, tested single dosing vs hopper on the same grinder.

Lately I've been lazy and filled up the hopper a bit (used to weigh and single dose always) and I find it remarkable how much you need to switch the grind setting.

Some thoughts:
1. The interaction between the bean and the burr must be quite different considering the change in grind setting to accomplish the same grind fineness. To the bean, this should appear as a differently designed burr, hence providing different characteristics when extracted.

2. When single dosing, the first beans to be ground may be ground very fine - too fine - as these have some pressure from the beans above. This may be compensated by the last beans which may be too coarse. I guess my theory here is that the single dosed grinds are less homogeneous than the hopper ones, basically a combination of fine and coarse to give the same result extraction time wise.

3. Assuming burrs are designed with filled hoppers in mind, could there be a market for burrs designed for single dosing, potentially minimizing the shortfalls above?

I am no engineer and don't know if that is at all possible but would certainly welcome a burr set that can be made with that theory in mind. Personally I have single dosed with a Vario, Mazzer Major, Super Jolly, Fiorenzato and a bunch of others. I have never been happy with the single dose method (on grinders not designed for it) as I find exactly what you said. The grind is not consistent throughout the whole grind process. I encountered a lot of spritzing and channeling while single dosing. I have had none of these problems since switching over to the HG One to single dose and the K10 Fresh with a full hopper for larger dosing needs.

Here you can find some more about it:

Single dose versus hopper grinding: an experiment

angman wrote:I am no engineer and don't know if that is at all possible but would certainly welcome a burr set that can be made with that theory in mind. Personally I have single dosed with a Vario, Mazzer Major, Super Jolly, Fiorenzato and a bunch of others. I have never been happy with the single dose method (on grinders not designed for it) as I find exactly what you said. The grind is not consistent throughout the whole grind process. I encountered a lot of spritzing and channeling while single dosing. I have had none of these problems since switching over to the HG One to single dose and the K10 Fresh with a full hopper for larger dosing needs.

For me, +1. On my Cremina, my pours were more consistent and rich with the Vario-W's hopper at least 1/3 full.

Bjornm,

Whatever you decide, if you choose to use the hopper, make sure you have enough beans in there to make the grind consistent. To do that, make sure you have beans up to and above the finger guard (that little "umbrella" thingy). That's about 2" high of visible beans. You'll notice that the grind size will change as the beans go down from there, to below. If you make sure to keep the height between let's say 4"-2" or 3"-2" you will get consistent grind size. In other words, the grind size will not change noticeably between 3-2", but will start to change when it goes lower than the finger guard (~2"). So fill up the hopper to that level (3-4 inches) when it goes down to the finger guard. Or better yet, figure out what you are using in one day and fill it up enough that by the end of the day you'll be at the finger guard level.

I theorize that with the Robur's auger that will be less of a problem since the auger feeds the beans at a consistent pressure into the burrs.