another_jim wrote:Absolutelty the other way around. If you feed one bean at a time, the burrs have to do all the grinding work. If the burrs are full of beans, they grind against each other as well. The more beans in the burrs, the finer the grind, for any given setting.

Ok, then divorce 'finer' from 'consistent'... wouldn't the burrs doing all the work result in a more consistent grind? Where you can then be very precise about coarse <> fine in how you set the grinder? Is there a dataset demonstrating better consistency by loading the grinder with beans than by feeding slowly? I seem to remember Hedrick doing a thing where feeding slowly had some benefit...

John Weiss was strongly of the opinion that popcorning and slow feeding was bad, not good. We dd some taste tests, and it turned out to be a toss up. You can be consistent either way by being ... um consistent .., i.e. sticking to one way or the other.

coyote-1 wrote:I would have imagined a slower feed of beans would result in a finer and more consistent grind. Is it the case that a fuller load of beans grinding at once causes a finer and more consistent grind?

Apologies in advance for continuing the OT discussion:
Yes. As Jim notes, grinding with a bean load yields a significantly finer grind. This is not a subtle effect; it's quite dramatic (try it sometime). Single dose grinders are great, practically essential if you like to experiment with different coffees on a daily basis. But I have never found single dosing to be as consistent. Newer grinders that are designed for this are, of course, much better at single dosing than grinders with hoppers.

When single dosing, you'd think that feeding in beans one by one would result in greater consistency (otherwise the bean load changes from ~18g to 0g as you grind). But when I acquired a Niche Zero, it was nearly unusable due to inconsistent grind. When I removed the flow control disc (which feeds beans one at a time), consistency improved dramatically. Still haven't figured that one out.

Thanks everyone. Super helpful. I tried changing two things this morning (one at a time obvs). First letting the machine warm up for 40 mins to ensure the grouphead was at temp. Sadly this resulted in the same problem. I then let the machine cool down for two hours. Then second filling the hopper rather than single dosing. That absolutely did the trick. I ground both shots at different times as before. So weird. Looks like my grinder is not suitable for single dosing. Both shots this time exactly the same 33 seconds for 18g in and 36 out with the paddle at 9.45 o'clock for about 20-25 seconds and then open to 9 bar.

So I think I'll just put out a few days worth of beans in the hopper and top up. I assume the pressure of the beans is needed to keep the grind size correct and somehow the residue left from the first grind affects the second grind.

I assume single dosers are different in this regard? Might look to invest in one of those in the near future to eliminate the problem.

Thanks all. I thought it was probably something simple that I was missing and knowing the knowledge on here it would be fixed asap. My wife is super impressed after having a month of me complaining.