Grinder mechanics ?

What makes one burr grinder better than another. I'm not asking about
quality of the machine, just the physics behind the grind.

I understand speed of the burrsis important, but I don't know why, if
any the size of the burrs matter. I realize the structure of them
machine has to be rigid enough to maintain the relative position of the
burrs to one another, but does the design of the burr really make a
difference?

Clay

The size of the burrs relates mostly to the rate of grind - the bigger the
burrs the more coffee you can grind in a given unit of time while keeping
quality constant. You can scale the burrs from pepper grinder size to mill
stone.

Other than the factors you gave (rigidity of burr gap, relatively low speed)
the other factor is burr sharpness. High quality burrs are machined tool
steel ground to sharp edges. Cheap burrs are cast and dull.

Conical burrs are found at the extreme ends of the market, with the safe
middle ground occupied mostly by flat burr grinders. The cheap conicals
rely on the self-centering nature of conical burrs rather than a rigid
mounting system, but that design has its limits.

"Crabman" <C@dud.net> wrote in message
news:477439a7$0$16680$4c368faf@roadrunner.com...
> What makes one burr grinder better than another. I'm not asking about
> quality of the machine, just the physics behind the grind.
>
> I understand speed of the burrsis important, but I don't know why, if any
> the size of the burrs matter. I realize the structure of them machine has
> to be rigid enough to maintain the relative position of the burrs to one
> another, but does the design of the burr really make a difference?
>
> Clay

Howdy Jack!
What inherent advantage does an inflexible set of conical burrs have
over an equally inflexible set of flat burrs?

Robert Harmon


On Dec 27, 5:57 pm, "Jack Denver" <nunuv...@netscape.net> wrote:
> The size of the burrs relates mostly to the rate of grind - the bigger the
> burrs the more coffee you can grind in a given unit of time while keeping
> quality constant. You can scale the burrs from pepper grinder size to mill
> stone.
>
> Other than the factors you gave (rigidity of burr gap, relatively low speed)
> the other factor is burr sharpness. High quality burrs are machined tool
> steel ground to sharp edges. Cheap burrs are cast and dull.
>
> Conical burrs are found at the extreme ends of the market, with the safe
> middle ground occupied mostly by flat burr grinders. The cheap conicals
> rely on the self-centering nature of conical burrs rather than a rigid
> mounting system, but that design has its limits.
>
> "Crabman" <C...@dud.net> wrote in message
>
> news:477439a7$0$16680$4c368faf@roadrunner.com...
>
> > What makes one burr grinder better than another. I'm not asking about
> > quality of the machine, just the physics behind the grind.
>
> > I understand speed of the burrsis important, but I don't know why, if any
> > the size of the burrs matter. I realize the structure of them machine has
> > to be rigid enough to maintain the relative position of the burrs to one
> > another, but does the design of the burr really make a difference?
>
> > Clay

"Robert Harmon" <r_h_harmon@m> wrote in message
news:39b88bd4-f330-4ab9-8a0a-0d4f647f42b7@e25g2000prg..com...
> Howdy Jack!
> What inherent advantage does an inflexible set of conical burrs have
> over an equally inflexible set of flat burrs?
>
> Robert Harmon

Hi Rob, I'm not Jack., but I've read/heard that conicals have more
contact/surface cutting area than flat parallel burrs.
Craig.

"Craig Andrews" <coffee@deletethis.rogers.com> wrote in message
news:5tj2puF1e07f1U1@mid....
>
> "Robert Harmon" <r_h_harmon@m> wrote in message
> news:39b88bd4-f330-4ab9-8a0a-0d4f647f42b7@e25g2000prg..com...
>> Howdy Jack!
>> What inherent advantage does an inflexible set of conical burrs have
>> over an equally inflexible set of flat burrs?
>>
>> Robert Harmon
>
> Hi Rob, I'm not Jack., but I've read/heard that conicals have more
> contact/surface cutting area than flat parallel burrs.
> Craig.

Oh, & slower conical burrs speed 500 - 800 rpm versus approx 1,600 rpm for
flat burrs. The slower conical burr speeds helps preserve volatile bean
aeromatics better due to the much slower rpm's & practically nil heat
generated.
Craig.

Craig Andrews wrote:
>
> "Craig Andrews" <coffee@deletethis.rogers.com> wrote in message
> news:5tj2puF1e07f1U1@mid....
>>
>> "Robert Harmon" <r_h_harmon@m> wrote in message
>> news:39b88bd4-f330-4ab9-8a0a-0d4f647f42b7@e25g2000prg..com...
>>> Howdy Jack!
>>> What inherent advantage does an inflexible set of conical burrs have
>>> over an equally inflexible set of flat burrs?
>>>
>>> Robert Harmon
>>
>> Hi Rob, I'm not Jack., but I've read/heard that conicals have more
>> contact/surface cutting area than flat parallel burrs.
>> Craig.
>
> Oh, & slower conical burrs speed 500 - 800 rpm versus approx 1,600 rpm
> for flat burrs. The slower conical burr speeds helps preserve volatile
> bean aeromatics better due to the much slower rpm's & practically nil
> heat generated.
> Craig.

Can someone point me to an image of the flat burr setup, please?

Clay

"Craig Andrews" <coffee@deletethis.rogers.com> wrote in message
news:5tj34aF1b3i9iU1@mid....
>
> "Craig Andrews" <coffee@deletethis.rogers.com> wrote in message
> news:5tj2puF1e07f1U1@mid....
>>
>> "Robert Harmon" <r_h_harmon@m> wrote in message
>> news:39b88bd4-f330-4ab9-8a0a-0d4f647f42b7@e25g2000prg..com...
>>> Howdy Jack!
>>> What inherent advantage does an inflexible set of conical burrs have
>>> over an equally inflexible set of flat burrs?
>>>
>>> Robert Harmon
>>
>> Hi Rob, I'm not Jack., but I've read/heard that conicals have more
>> contact/surface cutting area than flat parallel burrs.
>> Craig.
>
> Oh, & slower conical burrs speed 500 - 800 rpm versus approx 1,600 rpm for
> flat burrs. The slower conical burr speeds helps preserve volatile bean
> aeromatics better due to the much slower rpm's & practically nil heat
> generated.
> Craig.

So goes the theory, but how about in actual practice? I can understand how
and why this might make a difference in a commercial environment where heat
build up in the grind chamber might be a real issue, but how much of an
issue is this in a home grinder where you're only grinding a few grams of
coffee at irregular intervals?

My SJ only takes about 7 seconds to grind enough coffee for a double.
There's a whole lot of aluminum in the SJ's grind chamber and I'm thinking
it's going to take a lot of grinding before the temperature rises to any
measurable amount. It would be interesting to find out if there really is a
big difference. So far all I've seen is anecdotal evidence.

On Dec 27, 6:47 pm, Crabman <C...@dud.net> wrote:
> What makes one burr grinder better than another. I'm not asking about
> quality of the machine, just the physics behind the grind.
>
> I understand speed of the burrsis important, but I don't know why, if
> any the size of the burrs matter. I realize the structure of them
> machine has to be rigid enough to maintain the relative position of the
> burrs to one another, but does the design of the burr really make a
> difference?
>
> Clay

As much in a quality of precision. Think DNA strands and corkscrewed
spiraling ellipsis. It's where the connoisseur's grinder, minutely
adjustable, takes the above cut pattern into espresso territory, one
step above mortar-and-pestle, traditional arabic coffees. Nothing in
a theoretical realm more or less allowable, as applied to Italian-
inspired coffee dogma. The spiraling is best so to uniformly extract
all of coffee essences within a discrete espresso-timed limitation of
reproducible consistency. The more or less (deviation from size) is
neither to gather chemical compositions less than discriminately,
accordingly, or, for any allowance of fines, as they're known, to sift
through the filter-mesh and settle for an undesirable sedimentary
residue to a shot, in so many less than distinguished marks against
espresso terminology.

--
A girl's best friend is her mutter. -Dorothy Parker

Flasherly wrote:

>
> As much in a quality of precision. Think DNA strands and corkscrewed
> spiraling ellipsis. It's where the connoisseur's grinder, minutely
> adjustable, takes the above cut pattern into espresso territory, one
> step above mortar-and-pestle, traditional arabic coffees. Nothing in
> a theoretical realm more or less allowable, as applied to Italian-
> inspired coffee dogma. The spiraling is best so to uniformly extract
> all of coffee essences within a discrete espresso-timed limitation of
> reproducible consistency. The more or less (deviation from size) is
> neither to gather chemical compositions less than discriminately,
> accordingly, or, for any allowance of fines, as they're known, to sift
> through the filter-mesh and settle for an undesirable sedimentary
> residue to a shot, in so many less than distinguished marks against
> espresso terminology.
>
> --
That was a lotta help.
Clay

On Dec 27, 9:58 pm, Crabman <C...@dud.net> wrote:
> Flasherly wrote:
>
> > As much in a quality of precision. Think DNA strands and corkscrewed
> > spiraling ellipsis. It's where the connoisseur's grinder, minutely
> > adjustable, takes the above cut pattern into espresso territory, one
> > step above mortar-and-pestle, traditional arabic coffees. Nothing in
> > a theoretical realm more or less allowable, as applied to Italian-
> > inspired coffee dogma. The spiraling is best so to uniformly extract
> > all of coffee essences within a discrete espresso-timed limitation of
> > reproducible consistency. The more or less (deviation from size) is
> > neither to gather chemical compositions less than discriminately,
> > accordingly, or, for any allowance of fines, as they're known, to sift
> > through the filter-mesh and settle for an undesirable sedimentary
> > residue to a shot, in so many less than distinguished marks against
> > espresso terminology.
>
> > --
>
> That was a lotta help.
> Clay

Welcome. What I recall offhand from a forgotten site and article
sometime ago.