HarveyMushman Made a filter brew with the espresso burrs at around 60 and pleasantly surprised. Definitely not bad at all.
Well for some reason the influencers and a few posters on other forums are making out that without the filter burrs the grinder is inferior to other espresso focussed burr grinders when making filter. It’s not, it’s the same as any other espresso focussed burr at making filter.
The option of putting in specific filter burrs simply make it better, and better than other espresso focussed burrs in other grinders at filter.
The white elephant I keep talking about is that the technical characteristics of the espresso burr cause this and you can’t have a burr that does both well. This shows clearly on the filter burr, which absolutely won’t grind for espresso. The technical characteristics required for a filter burr, make that impossible.
I’ll do my best to explain the problem (perhaps it should be an article).
Flat Espresso burrs have a small grind path and have to be close together 80 -120 ish Micron in slow rotational burr speed single dosers. In higher rotational speed (for burr size) and hopper fed grinders that goes up to around 180 - 200 micron. This in itself is very interesting and the subject of another discussion.
Imagine now you want to use those espresso burrs for filter, you have to open them right up to a gap for 500+ micron. When that happens, the grind path is not really regulating size, the burrs are too far apart for that and the mill down characteristics are lost, with goffee grinding against itself. This is why ghost burrs work BTW
Of course an espresso burr doesn’t look like this and by widening the gap, coffee is grinding against itself…the small channels are doing very little but adding roughness. This gives a filter that lacks sweetness, I’m suspecting because the grind can have lots of fines and also uneven boulders
The FILTER focussed burrs when held together, show much larger coffee exit paths around the periphery (which is why they won’t grind for espresso. So they are already a large part of the way there for filter and increasing the gap for coarser grinds doesn’t mean coffee avoids the grind path altogether. the total gap is smaller and less coffee is grinding against itself at any given moment. Leading to……..better filter.
In some ways the Duo with espresso burrs might well be better than other espresso focussed grinders/burrs at filter, simply because of the much slower rotational speed of the grinder. This is theory though any cannot be proven, but would make sense.
