Conical Burr Consistency: Myth or Reality? - Page 3

#21: Post by **redbone** » December 4th, 2018, 1:13 pm

RapidCoffee wrote:Robert, I'm not trying to harp upon this. But I'm still having difficulty understanding these claims. What is meant by "adhere closer together"? What studies/observations show a difference in shape between conical and flat burr grinds?

No citations were made. Based on my experience when I used a conical burr grinder I noticed the flow of espresso remained the same for weeks without having to make grind adjustments. It seemed that the grind must be shaped different enough whereby they acted as they adhered to each other like a puzzle vs flat burr grinds.

#22: Post by **another_jim** » December 4th, 2018, 1:20 pm

RapidCoffee wrote:Jim, you may already have hinted at one reason:

Beans may feed more smoothly into the vertical geometry of conicals, but "popcorn" more with the horizontal geometry of flats. This could even be a factor with a bean load.

But how would this affect the final grind? At what point of the bean's journey from the inside/top of the burr to the outside/bottom is the final particle distribution determined? If the feed-in has a big effect on the final grind quality; we could have saved ourselves lots of time when testing grinders

#23: Post by **RapidCoffee** » December 4th, 2018, 2:28 pm

Either it's geometry, or there are other differences in the burrs. Given the consistent agreement, across different models, that conicals are more forgiving, I lean towards the former.

Looking back at the landmark titan grinder study, with the benefit of many years experience... yes, there are many things we could have done differently. For example, we tested essentially new grinders. Burr break in? Nah, never heard of it.

#24: Post by **ttttt91** » December 4th, 2018, 11:56 pm

I am pretty new to all this stuff, so forgive my ignorance...

one explanation from what I read (could be all wrong):

- Conicals are claimed to make more fines
- Conicals might make more fines because there is more "cracking" vs "grinding" (When I look at the burrs, it seems that with conicals all beans get first cracked before getting ground. Flats may grind more.....)
- If conicals have indeed more fines than I could believe that fines are a factor in how water flows through the puck. Meaning, fines fill the space between the bigger grounds and "block" the flow of water. In that case, if the bigger grounds get bigger or smaller would not matter that much cos fines are filling in the little spaces always and kind of tighten the puck. For flats, IF all grounds are same (with fewer fines) then the actual particle size plays a bigger role...

December 5th, 2018, 12:26 pm

It's a pretty good explanation.

Beans are like toast, crack one and you get crumbs, aka fines. If you make the grind finer, you get more cracks and more fines. You also get smaller particles. So when you change the grind setting, you change both the number of fines and the course particle size. Your idea is that if the fines change more rapidly than the the particle size, the grinder is more forgiving, and vice versa.

I think this is roughly true. We tried to measure it, but the laser sizing gear used to measure grinder particle size wasn't sensitive enough to pick up the small changes in the range used for dialing in shots.

December 6th, 2018, 8:09 am

For what small amount this may be worth, my EK43s with the Turkish burrs, new style prebreaker(auger) and chamber has been very consistent with few minor grind adjustments needed day to day once it settled after breakin. It is quite similar to what I have been experiencing with my Kafatek Monolith Conical in that respect. Full disclosure, my KMC is from the second batch sold so it may be different from later versions but it has been very repeatable. When I was considering this grinder I spent a fair amount of phone time with a rep from Mahlkonig USA and he was adamant that the prebreaker was a huge improvement over previous iterations. I do not know if this prebreaker is only applicable to the Turkish burr models but I seem to recall it was for all EK43s models. This seems to validate anotherJims thoughts but is strictly subjective from my point, no scientific data to confirm .

December 6th, 2018, 12:43 pm

The prebreaker is working if the grind time for very fine grinds is not a lot longer than for coarser grinds. If that also improves consistency, it would tend to prove John's point that the feed in is just as important as the rest of the burr geometry.

... If the prebreaker is removable, you could do the experiment of timing the grind times ... pretty please.

#28: Post by **redbone** » December 6th, 2018, 1:58 pm

Just to add a third option.
A DRM burr grinder with it hybrid dual burrs uses the first burr as a pea breaker followed by the secondary burr to focus on finer grinding.

Invented by DRM srl and popularized more recently by Versalab. http://lnx.pielle.biz/drm/wp-content/up ... ng-ita.pdf