renatoa wrote: For example the output difference between Feldgrind and Kinu M38 is almost double, like in 30 vs 48 seconds, to grind same beans, turned at same (electric) RPM. But the Kinu M38 requires 40 Nm force compared to 18Nm force required by Feldgrind can anyone explain this difference other than burrs shape ?

Maybe it's worth splitting into a new thread.

The Feldgrind has coated burrs, Kinu doesn't. Coated burrs are more slippery and have less friction, thus less efficient at grabbing beans. This behavior was noted on HG-1 previously (TiN-coated vs non coated).

Would be a nice experiment if the Sette's burrs could be used on another grinder. That will put the hypothesis to rest.

From Baratza FAQ:

Explain the movement of the outer burr and how/why that pulls the beans in and makes for faster speeds
Aggressive helical grooves cut into the top of the rotating outer ring burr are what actively pull beans down between the burrs, while another helical compressor ring at the base of the rotating ring burr gathers the resultant grinds and compresses them slightly while guiding them out, which helps dissipate static charge. "You need coffee to bunch up a little bit after it's been ground," said Anderson, "or you will have a static nightmare."

Note that Baratza did not claim that the Sette is faster because they are turning the outer burr, but because of the grooves on the outer burr.

It's way different having the outer burr turn. The reason is the bean is fed with zero velocity relative to the stationary burr, and with a large difference in velocity relative to the moving burr. The physics of what happens is going to be very different because of this.

As good as the Sette probably is, non-replaceable burrs are a deal breaker. I can't bring myself to buy a throwaway grinder. Traditional grinders are lifetime investments for a home user. The world needs less throwaway stuff...

DaveC113 wrote:non-replaceable burrs are a deal breaker. I can't bring myself to buy a throwaway grinder

I haven't done it myself, but am fairly sure the inner burr is replaceable, but am not sure about the outer burr. My local Baratza dealer was confident the regular and BG burrs could be replaced and used interchangably. Looking on reddit it seems people have replaced the espresso burr with BG burr without issue:

'Fyi it's a direct replacement for the center burr, pops in easily and is clearly different from the fine burr design. Pics here-'

https://www.google.co.nz/amp/s/amp.redd ... 70_coarse/