Conical Burr Consistency: Myth or Reality?

Grinders are one of the keys to exceptional espresso. Discuss them here.
sluflyer06

Postby sluflyer06 » Dec 03, 2018, 10:00 am

So we've all heard the opinion that Conical burrs require less adjustment over time as beans age, temperature changes, humidity changes to maintain the same extraction time...but is it actually true?

I had a K30 Vario for 3.5 years, by any standard on this forum, an exceptionally good grinder, about 3.5 weeks ago I received my 10th run MonoCon and I've pulled around 110 shots on it now (no break-in beans were run through it) and in this time since getting this bean dialed in I have had to adjust the grind size exactly once to slightly finer and some of that is just break-in possibly. 3 of 5 shots are within 1 second of target and others are within 2.

The consistency is pretty unreal, my K30 required constant adjustment and it was not rare to have a 26s shot one morning and wake up the next day and it was 4-5 seconds off requiring significant adjustment. I'm sure some part of this is the way the Monolith is built, but again K30 has a stellar reputation for build and is a $1600 grinder.

Based on my own experience, I'm going to say REALITY.

User avatar
redbone

Postby redbone » Dec 03, 2018, 10:09 am

This comes down to the grind type these burrs produce. Flat produce mostly uniform grind particles or unimodal. Conical burrs produce bimodal grind particles and cluster closer together. Taste preferences vary per individual and roasted coffee used.

Grinder Tech
Between order and chaos there is espresso.
Semper discens.


Rob
LMWDP #549

sluflyer06

Postby sluflyer06 » replying to redbone » Dec 03, 2018, 10:47 am

I'm already aware of the grind types between the two, thanks.

User avatar
Peppersass

Postby Peppersass » Dec 03, 2018, 1:45 pm

To my knowledge, no one has run rigorous tests to compare consistency between conicals and flats, which would be complicated by the large number of grinders that would have to be tested in different configurations (hopper, single dose, etc.), all with exactly the same beans in exactly the same state of roast/aging.

My own experience has been that flats like my first grinder, a Macap M4, and my second grinder, a Vario-W, were not consistent, and that when I upgraded to a Compak K10 I discovered the true meaning of consistency -- that grinder is rock solid and repeatable. For a long time I thought this was due to the difference between flats and conicals, but when I upgraded to my Monolith Flat I found exactly the same consistency as the K10.

My sense is that consistency depends on 1) burr size, 2) amount of beans in the hopper (if used), suitability for single-dosing (if used), and 3) a combination of burr geometry and retention. No scientific evidence, just my gut feel.

If you were using the hopper with your K30, the level of beans in the hopper, possibly in combination with the type of bean, caused some inconsistency.

User avatar
FotonDrv

Postby FotonDrv » Dec 03, 2018, 2:02 pm

I would tend to agree with Dick.

My Conicals have been consistent, but the Mono Flat is also very consistent once broken in, which I had to do again when the RedSpeed burrs were put into it. Now it is rock solid.
That Light at the End of the Tunnel is actually a train

nuketopia

Postby nuketopia » Dec 03, 2018, 2:52 pm

I have had my Monolith Conical for a few years. I do adjust a bit as beans age out. Not much, just a little sometimes depending on how fast I'm using them. I've noticed that temperature has some effect as well.

Since the Mon-Con is a single doser and I weigh each dose, it always has the same feed pressure behind it. I would expect a hopper-fed grinder to have variable results, based on the weight of beans in the hopper.

User avatar
another_jim
Team HB

Postby another_jim » Dec 03, 2018, 3:21 pm

Peppersass wrote:To my knowledge, no one has run rigorous tests to compare consistency between conicals and flats, which would be complicated by the large number of grinders that would have to be tested in different configurations (hopper, single dose, etc.), all with exactly the same beans in exactly the same state of roast/aging.


Ahem, during the Titan grinder tests we had 7 or 8 grinders using the same coffee and dose and doing comparison shots. The consensus of all testers was that it was very hard to distinguish taste, and very easy to distinguish the dial in effort. It became a kind of joke when we doing the tests ("how about we do dial in tests instead of taste tests"). However, we had no large flat burr grinders. Dominick has both the flat and conical Monolith, and he's found the dial in effort less on the conical.

There is one new area though ... We had a chance to do side by sides at the least meetup. On very light roasts, the flat was easier to use, and allowed higher dosed well extracted shots, even when using all the profiling tricks on the Bianca and manual levers. Profiling machines make precise grind and dose adjustments redundant (long preinfusions correct the mistakes), and light roasts put a premium on high extractions, so for the combo of light roasts on profiling machines, life may be easier with a large flat.

But this suddenly made another old area important ... the "bean suction" of large flats used in single dose mode needs work. The Monolith flat really slows down on finer grind settings when compared to the conical. Struggling with fine grinding in single dose mode interferes with the whole high extraction gig. The grinder artisans producing large flat burr hobbyist grinders need to experiment with well designed augurs. Conicals do not need them, flats do.
Jim Schulman

User avatar
FotonDrv

Postby FotonDrv » Dec 03, 2018, 3:37 pm

another_jim wrote: The grinder artisans producing large flat burr hobbyist grinders need to experiment with well designed augurs. Conicals do not need them, flats do.


The Titus does exactly that, and I would love to try one, and actually buy one if the monies were available.
That Light at the End of the Tunnel is actually a train

User avatar
RapidCoffee
Team HB

Postby RapidCoffee » Dec 03, 2018, 4:09 pm

redbone wrote:This comes down to the grind type these burrs produce. Flat produce mostly uniform grind particles or unimodal. Conical burrs produce bimodal grind particles and cluster closer together.

Both flat and conical burrs produce bimodal espresso grinds. The finer the grind setting, the more fines are generated. It is possible that conical burrs produce more fines than flat burrs, but experimental evidence seems pretty weak on this score.

Can you explain what you mean by "cluster closer together"?
John

RyanJE

Postby RyanJE » Dec 03, 2018, 4:37 pm

another_jim wrote:Ahem, during the Titan grinder tests we had 7 or 8 grinders using the same coffee and dose and doing comparison shots. The consensus of all testers was that it was very hard to distinguish taste, and very easy to distinguish the dial in effort. It became a kind of joke when we doing the tests ("how about we do dial in tests instead of taste tests"). However, we had no large flat burr grinders. Dominick has both the flat and conical Monolith, and he's found the dial in effort less on the conical.

There is one new area though ... We had a chance to do side by sides at the least meetup. On very light roasts, the flat was easier to use, and allowed higher dosed well extracted shots, even when using all the profiling tricks on the Bianca and manual levers. Profiling machines make precise grind and dose adjustments redundant (long preinfusions correct the mistakes), and light roasts put a premium on high extractions, so for the combo of light roasts on profiling machines, life may be easier with a large flat.

But this suddenly made another old area important ... the "bean suction" of large flats used in single dose mode needs work. The Monolith flat really slows down on finer grind settings when compared to the conical. Struggling with fine grinding in single dose mode interferes with the whole high extraction gig. The grinder artisans producing large flat burr hobbyist grinders need to experiment with well designed augurs. Conicals do not need them, flats do.


Jim, just curious, what RPM was the flat used at?

I have owned both a MonCon and Flat and would say both are very consistent and easy to dial in and stay very consistent. What I have noticed though with the flat compared to the conical is that the adjustment tick marks make larger changes in resulting shot flow. One tick on the conical represented less flow difference, all else held consant, than one tick mark on the flat (in my experience).

Quite honestly, I'm splitting hairs since you can go in between tick marks easy enough, but I sense just MAYBE the threading could have been done differently on the flat to negate this... Not sure if this is true on current lock less iterations...
I drink two shots before I drink two shots, then I drink two more....