Commercial Coffee Grinders

[Mark Thorson]

What grinders are commonly used for local commercial grinding
operations (such as Peet's, etc.)? About how much throughput
do these machines have (in terms of pounds/minute, or something
like that)?

I've been having trouble finding information like that. One
machine I looked at, which would be sized for a restaurant-type
operation -- not a coffee business -- said it had something
like 2 pounds/hour, which seems to me has got to be a mistake.
How could a machine costing $1000 have such a low throughput?
I would expect a machine like that to have a throughput
of 2 pounds/minute or faster.

Also, the grinders I see offered for restaurant or high-end
personal use all seem to use flat or cone grinding burrs.
Do commercial coffee grinders use roller mills? If not,
why not? Flat or cone burrs crush the product as much
as grind it, while rollers have much more of a shearing or
cutting action. This is a lesson learned well over 100 years
ago in the flour milling industry, when the old millstones
were completely replaced by the vastly superior roll mills.

Also, coffee grinders all seem to operate in a single stage,
going right from the whole bean to the finished product
in one grinding step. A typical commercial flour milling
operation uses four grinding steps. Is there commercial
coffee grinding equipment designed for multiple passes
of grinding?

[unknown]

Post by Mark Thorson
What grinders are commonly used for local commercial grinding
operations (such as Peet's, etc.)? About how much throughput
do these machines have (in terms of pounds/minute, or something
like that)?
I've been having trouble finding information like that. One
machine I looked at, which would be sized for a restaurant-type
operation -- not a coffee business -- said it had something
like 2 pounds/hour, which seems to me has got to be a mistake.
How could a machine costing $1000 have such a low throughput?
I would expect a machine like that to have a throughput
of 2 pounds/minute or faster.
Also, the grinders I see offered for restaurant or high-end
personal use all seem to use flat or cone grinding burrs.
Do commercial coffee grinders use roller mills? If not,
why not? Flat or cone burrs crush the product as much
as grind it, while rollers have much more of a shearing or
cutting action. This is a lesson learned well over 100 years
ago in the flour milling industry, when the old millstones
were completely replaced by the vastly superior roll mills.
Also, coffee grinders all seem to operate in a single stage,
going right from the whole bean to the finished product
in one grinding step. A typical commercial flour milling
operation uses four grinding steps. Is there commercial
coffee grinding equipment designed for multiple passes
of grinding?

I don't hava an answer to a single one of your questions, but it sure
sounds like you have the design for a superb, if not particularly
cheap, grinder. I expect that the reason we aren't using four-stage
grinders is that it's too expensive.



Loading Image...

[pltrgyst]

Post by Mark Thorson
What grinders are commonly used for local commercial grinding
operations (such as Peet's, etc.)? About how much throughput
do these machines have (in terms of pounds/minute, or something
like that)?

My Ditting KR804 does a pound a minute. I see these machines in a lot of coffee
houses, supermarkets, and gourmet shops. It's a wonderful machine to have at
home -- I haven't seen anything yet I'd trade for.

The Ditting 1200s do 3 lb/min on 110 vac, and 6lb/min on 220 vac, 3-phase.
(www.ditting.com)

-- Larry

[bdigman]

Post by Mark Thorson
What grinders are commonly used for local commercial grinding
operations (such as Peet's, etc.)? About how much throughput
do these machines have (in terms of pounds/minute, or something
like that)?
I've been having trouble finding information like that. One
machine I looked at, which would be sized for a restaurant-type
operation -- not a coffee business -- said it had something
like 2 pounds/hour, which seems to me has got to be a mistake.
How could a machine costing $1000 have such a low throughput?
I would expect a machine like that to have a throughput
of 2 pounds/minute or faster.
Also, the grinders I see offered for restaurant or high-end
personal use all seem to use flat or cone grinding burrs.
Do commercial coffee grinders use roller mills? If not,
why not? Flat or cone burrs crush the product as much
as grind it, while rollers have much more of a shearing or
cutting action. This is a lesson learned well over 100 years
ago in the flour milling industry, when the old millstones
were completely replaced by the vastly superior roll mills.
Also, coffee grinders all seem to operate in a single stage,
going right from the whole bean to the finished product
in one grinding step. A typical commercial flour milling
operation uses four grinding steps. Is there commercial
coffee grinding equipment designed for multiple passes
of grinding?

The numbers must be wrong. A small Ditting for shop use will easily
do 20 or 30 lbs an hour which would be a pretty good clip. You are
correct that the mills used for mega-roasters are of the roller type.
They are measured in the thousands of pounds per hour, water cooled,
etc. I believe all at that range are multi-stage. You can ususally pick
one up for around $150K but you have to supply your own 11yard dump
truck to feed it.

[DrEspresso]

Post by Mark Thorson
What grinders are commonly used for local commercial grinding
operations (such as Peet's, etc.)? About how much throughput
do these machines have (in terms of pounds/minute, or something
like that)?
I've been having trouble finding information like that. One
machine I looked at, which would be sized for a restaurant-type
operation -- not a coffee business -- said it had something
like 2 pounds/hour, which seems to me has got to be a mistake.
How could a machine costing $1000 have such a low throughput?
I would expect a machine like that to have a throughput
of 2 pounds/minute or faster.
Also, the grinders I see offered for restaurant or high-end
personal use all seem to use flat or cone grinding burrs.
Do commercial coffee grinders use roller mills? If not,
why not? Flat or cone burrs crush the product as much
as grind it, while rollers have much more of a shearing or
cutting action. This is a lesson learned well over 100 years
ago in the flour milling industry, when the old millstones
were completely replaced by the vastly superior roll mills.
Also, coffee grinders all seem to operate in a single stage,
going right from the whole bean to the finished product
in one grinding step. A typical commercial flour milling
operation uses four grinding steps. Is there commercial
coffee grinding equipment designed for multiple passes
of grinding?

A popular retail grinder for Peet's has been the Mahlkonig VTA6S it's rated
at about 5 lbs per minute. The Ditting KFA series is also in the same per
minute range, both are available 220v 3 phase for even faster grinding.
Roller mills are used for high volume continous feed applications with 2 or
more sets of rollers. Many have liquid cooled heads and are rated for
1,000's of lbs per hour.

[Mark Thorson]

Post by DrEspresso
A popular retail grinder for Peet's has been the Mahlkonig VTA6S it's rated
at about 5 lbs per minute. The Ditting KFA series is also in the same per
minute range, both are available 220v 3 phase for even faster grinding.
Roller mills are used for high volume continous feed applications with 2 or
more sets of rollers. Many have liquid cooled heads and are rated for
1,000's of lbs per hour.

Thanks, and to bdigman as well.

I don't think it should be necessary that a roll mill design
would only be suitable at 1000+ lbs/hr. I can easily
imagine a countertop design. I think there may be an
opportunity for a lower-end roller mill, sized for a local
grinding operation.

It would give you a much narrower particle size distribution,
and it should run much cooler than a flat or cone mill.

An advantage of the flat or cone mill is that they are
adjustable over a certain range. The gap on a roll mill
is adjustable too, but if you want to preserve the narrow
size distribution, you would swap rolls instead of adjusting
the gap. (Actually, you'd do both.)

I suppose it would have to be either multistage, or you'd
run the same coffee through a single-stage machine multiple
times (changing the rolls each time).

[Mark Thorson]

Post by Mark Thorson
An advantage of the flat or cone mill is that they are
adjustable over a certain range. The gap on a roll mill
is adjustable too, but if you want to preserve the narrow
size distribution, you would swap rolls instead of adjusting
the gap. (Actually, you'd do both.)

I spent a bunch of time carefully examining the pictures
of grinding burrs on the sweetmarias.com web site,
and I think it might be possible to improve on the
performance of flat burr machines simply by making
a drop-in replacement for the burrs. Any burr design
intended to cover the range from French press to
espresso isn't going to be optimal at the extreme ends
of its range. For example, sweetmarias.com says that
French press isn't the strong suit of the Rocky grinder.

If someone were only going to use their flat burr
grinder for one type of grind, it should be possible
to give them a better product by replacing the burrs
with ones optimized for that grind. Does anyone
have any idea how many high-end personal grinders
like the Rocky get sold each year? I'm wondering
whether it would be worth developing replacement
burrs. Certainly, they would be easy to design, test,
and manufacture. And, I think the sort of people
who buy machines like these would be interested
in any genuine improvement -- they aren't the sort
of people who are indifferent to the quality of the
grind.

A set of French press burrs for the Rocky might be
a good initial product. Any comments?

[Andy Schecter]

Post by Mark Thorson
I spent a bunch of time carefully examining the pictures
of grinding burrs on the sweetmarias.com web site,
and I think it might be possible to improve on the
performance of flat burr machines simply by making
a drop-in replacement for the burrs. Any burr design
intended to cover the range from French press to
espresso isn't going to be optimal at the extreme ends
of its range. For example, sweetmarias.com says that
French press isn't the strong suit of the Rocky grinder.
If someone were only going to use their flat burr
grinder for one type of grind, it should be possible
to give them a better product by replacing the burrs
with ones optimized for that grind.

You don't specify what you mean by "improve on the performance." If you mean
grind with less heat buildup, that would be good. If you mean stay sharp longer,
that would be good. If you mean grind faster, that would be good, too.

If you mean grind with a tighter particle distribution, that may or may not be
good, at least for espresso preparation. In his book "Espresso Quality," Andrea
Illy postulates that a bimodal particle distribution (a mixture of coarse and
fine particles) appears to optimize the espresso extraction. And in a personal
conversation on the same topic, Dr. Joseph John talked about a German grinder
that was "too precise to make good espresso."

If you do come up with an alternative set of Rocky or Mazzer Mini burrs, I'd be
very interested to test them.

[Mark Thorson]

Post by Andy Schecter
If you mean grind with a tighter particle distribution, that may or may not be
good, at least for espresso preparation. In his book "Espresso Quality," Andrea
Illy postulates that a bimodal particle distribution (a mixture of coarse and
fine particles) appears to optimize the espresso extraction. And in a personal
conversation on the same topic, Dr. Joseph John talked about a German grinder
that was "too precise to make good espresso."

That could make sense. In designing plastic formulations
for high filler loading -- in my experience, formulations for
plastic-packaged integrated circuits -- you want a bimodal
particle size distribution with the small particles sized to
fill the interstitial spaces between the large particles. That
allows you to get plastics that are >90% silica filler.
(It could be argued that they aren't plastics anymore,
they're polymer-modified ceramics.)

In coffee, this could affect the density of a charge of
coffee, and its resistance to how quickly water could flow
through. It would be less porous, because the small
particles would plug up paths through the cake.

[Felix Yen]

Any burr design intended to cover the range from French press to
espresso isn't going to be optimal at the extreme ends of its range.

Lacking any theoretical understanding of grinding, I reached the same
conclusion via trial-and-error.

A set of French press burrs for the Rocky might be a good initial
product. Any comments?

I'd be astonished if there's enough demand for such products, and burr
replacement usually requires more time/skill than most consumers have.
For example, here are directions for accessing the burrs of an older
Gaggia MDF:

After removing the hopper and face plate, adjust the grinder so its
setting is easy to remember, paying attention to the orientation of
the dial's mounting plate. Record this setting and orientation before
removing the dial and reinstalling two adjacent mounting screws to
facilitate counting revolutions. Pull the upper burr carrier upward
while removing it to determine exactly when the threads disengage.

(For the grinder I'm cleaning, this occurs 8.875 revolutions from its
coarsest setting. It might be simpler to use the classical reassembly
technique of bringing the burrs together and then backing off a bit.
However, just removing all the ground coffee before reassembling is a
chore.)

Furthermore, many grinders have an adjustment range that's less than
one revolution, so the range of settings for a particular application
lies in a small arc. A stepless design lets you use the entire arc,
but fine tuning would be easier if it were larger. In other words,
replacing the burrs in such a grinder would help, but the result would
still be flawed.

(If I were using my MDF for espresso, I would reassemble it without
its detents, thereby converting it to a stepless design.)


Felix

[Coffee for Connoisseurs]

First, I have 2 types of commercial grinders, Mahlkoenig and
Ditting, 2 of each <G>. Second, burr design doesn't have <that> much
effect on "grind for process", it's the gap BETWEEN the burrs (or
the rollers) that's important. Third, roller mills don't scale all
that well, (and I have a lot of experience in non-coffee related
industry to back that assertion up) and are very expensive to
manufacture to the precision required. See
http://www.buhlergroup.com/default.asp , the Buhlers are the
Dittings of the roller mill industry. Finally, it sounds like you're
about to try and re-invent the wheel. Unless you have great depth of
experience in the industry involved, you'll waste a lot of time
recapitulating stuff other people invented 50 years ago. Find out
what works FIRST before you try to go beyond it.

Alan

***@coffeeco.com.au
www.coffeeco.com.au

[unknown]

Post by Coffee for Connoisseurs
First, I have 2 types of commercial grinders, Mahlkoenig and
Ditting, 2 of each <G>. Second, burr design doesn't have <that> much
effect on "grind for process", it's the gap BETWEEN the burrs (or
the rollers) that's important.

snip

Post by Coffee for Connoisseurs
Alan
www.coffeeco.com.au

Just how good in your opinion are these/your grinders at maintaining a
narrow particle size distribution. I am looking at purchasing something
and am looking at the Ditting (they don't get much better I know) and a
mazzer with 140mm burrs. For instance do you have much in the way fines
in cup brewed with a presspot?

Trev

[Dan Bollinger]

Post by Mark Thorson
What grinders are commonly used for local commercial grinding
operations (such as Peet's, etc.)? About how much throughput
do these machines have (in terms of pounds/minute, or something
like that)?

Most use Mazzers, Bunns or Ditting, all burr machines. The smallest coffee roller mill I know of is the MPE model SRM 4555 http://www.mpechicago.com/coffee/Model-SRM4555/model_srm_4555.htm I have no idea what the price is.

[Mark Thorson]

The smallest coffee roller mill I know of is the MPE model SRM 4555 http://www.mpechicago.com/coffee/Model-SRM4555/model_srm_4555.htm I have no idea what the price is.

Thanks for the link. That machine looks to be exactly
what's needed for the bottom of the roller mill price range.
I'll have to find out what they cost, out of curiousity.

I notice the particle size distribution graph they show
was made with a Ro-Tap. I've used those, that's a
miserable way to get that data. A Ro-Tap is a sieve
shaker. To do a particle size distribution analysis the
hard way, you assemble a stack of sieves of different
sizes with the coarsest mesh on top, put your product
in the top sieve, then place the whole stack in the Ro-Tap.
The Ro-Tap both makes a swirling motion in the horizontal
plane, and shocks the stack with a good hard whack
on top about twice a second. That hammering sound
will drive anyone in the room or nearby crazy after
a few hours (or less). The materials I worked wouldn't
go through a sieve worth a darn, even running the Ro-Tap
for days. I don't know how easily coffee goes through
sieves.

Another solution is to use a sonic sifter with your
stack of sieves. I never worked with one of those,
so I don't know what they're like.

I wonder if there would be much demand for an
instrument that could perform a particle size distribution.
Ideally, I suppose you just put a sample in the
machine, press a button, and a display shows you
a bar graph or something. If it could show recognizable
differences between different brands of grinders,
different grind settings on the same grinder, worn vs.
new burrs, bean-specific differences in the resulting
particle size, etc., I wonder how many could be sold?
I can imagine how this might work -- maybe even as
a pocket unit. Consider how small the market probably is,
I doubt it could be cheap.

[Dan Bollinger]

Post by Mark Thorson
Thanks for the link. That machine looks to be exactly
what's needed for the bottom of the roller mill price range.
I'll have to find out what they cost, out of curiousity.

Let me know when you find out. Just out of curiosity.

Post by Mark Thorson
I wonder if there would be much demand for an
instrument that could perform a particle size distribution.

I know there are laser devices, but they measure the average particle size, not the distribution.