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OE PHAROS Hand Coffee Grinder



The PHAROS is the culmination or an ongoing 3 year project at OE involving hand coffee grinding and grinders.   These grinders range  from the very early lap mills with oversized wooden boxes and big top funnels to the modern manufacture German, Italian, and French box mills as well as the Japanese ceramic burr grinders....with some old and new brass Turkish mills as well.   We, and others, have gravitated to the use of hand grinders from the "golden age" of European box mills, using designs from German makers Zassenhaus, Dienes, KyM and others, as well as Italian Tre Spade for fine espresso grinding, and our preference for french press....Peugeot of France.

With every grinder a central question arises....WHY does this grinder perform in any specific way?    What are the design characteristics that makes one grinder perform FAST and another SLOW?   What burr bearing system is advantageous for espresso grinding?  What functional elements promote an even coarse grind from one grinder which will not perform well in the fine ranges?    How can it be that one mill with evident burr wobble and obvious burr wear can produce consistent espresso grind while another grinder, seemingly never used,  does not grind to consistent particle size for almost ANY coffee brewing method?   The answer of choice to all of these questions would be of course....MAGIC!!!....MYSTERY!!!....but in reality it is DESIGN and ENGINEERING.

We began our PHAROS project  with a set of functional demands that we have for a hand grinder and 3 years of feedback from other hand grinder aficionados....an ideal hand grinder should be:
  • Fast...giving a good speed to power ratio to allow rapid grinding at all coarseness levels...no one, it seems appreciates a slow grinder.
  • Consistent....producing uniform particle size through the range with incremental stepless burr adjustment
  • Convenient....changing grind settings should be direct and understandable, not to mention repeatable
  • Maintainable....the grinder should be easily taken apart for cleaning
  • Durable....hand built to last and not a use it and toss it item
  • Sustainable...all parts can be replaced for any reason for infinite use
The heart of the PHAROS is a 68mm conical  coffee grinding burr set as used in top of the line commercial grinders.  We built the grinder around this burr.  

  • The inner burr is mounted in the center of a long stainless steel axle which is held at the top and bottom with replaceable oil-less bronze bearings center fit into the top and bottom plates. 

  •  The outer burr is attached to the center plate using 4 bolts, with the upper hopper chamber composed of a clear poly carbonate sleeve held inside the bolts.   The pc cylinder above the burr creates an internal hopper which holds about 21 grams of beans.  Cylinder filling is through the openings at the top plate bearing.  

  • The functional demand of this design is that all elements are precisely centered in relation to each other to allow for maximum centered alignment of  the burr, axle, and assembly plates.
  • The grind adjustment is made using 2 knurled nuts at the top of the axle, under the handle.   The lower thumb nut is moved up or down the threaded shaft to establish the grind setting (the gap between the inner and outer burr) and the upper thumb nut is tightened down against the lower to lock the setting.  Adequate tightness of these two nuts is generally made with the fingers only but additional torque for tightening can be added by use of a bar or pin to tighten these two nuts against each other.  The turning handle is installed above these two adjustment nuts by use of a custom made thin jam nut...all topped off by a top cap which covers and protects the threads. 

  • The lower grinds hopper is composed of ABS plastic with cap head bolts installed into the upper and lower edges, which are in turn fit into holes in the center and lower plates.   The thick walled ABS with its alignment bolts prevents torsional stresses from distorting the mechanism and provides the structural rigidity needed to withstand the forces produced while grinding.   The lower grinds hopper contains a molded ABS plastic funnel, penetrated by the burr axle which terminates through the bottom plate of the machine.   The funnel is closed with a rubber stopper.

  • The aluminum plates and components within are all held firmly by the use of long assembly bolts.   There is no glue or other fasteners used in the machine so it can all be taken apart and reassembled as desired.   PVC standoff bolt covers are added on the assembly bolts to allow assembly without danger of over tightening and bending the aluminum plates...no tuning or fiddling is required, simply assemble and tighten the bolts to snug.
  • For rock solid stability when used as a counter top grinder, the Pharos uses a dense custom pad made from 100% recycled rubber to fully support the machine.

The result of our efforts has been to meet all of our stated design priorities, and exceed them in some areas....The PHAROS is:
  • Fast AND powerful....grinds at all coarseness levels at about 25 turns per tablespoon of beans, Turkish to French Press with increasing turning force required for finer settings
  • Very uniform fine grinds and  from our tests a good coarse grind (this is the hardest grind to produce on any grinder) with about 5% of the grinds passing through a .5mm test screen.  We have read that when grinding fresh beans on a coarse setting that these unavoidable "fines" are likely inert particles of the bean hull and do not effect extraction.
  • The top adjustment makes the grinder convenient to set and change adjustment settings.   If one looks at the grinder from the top and think of a clock face, then partial and full revolutions of the set nut can be established quite simply....inserting the bar or pin in a hole of the lower set nut will allow an even finer degree of visualization of the movement of this nut and very small changes can be made in the setting.
  • For cleaning  the lower hopper or burrs, the lower plate is removed to access the grinding mechanism.   Remove the lower frame assembly nuts and bolts, take off the handle and it is all in front of you for service.  Assembly is simple and the burr alignment is not changed during cleaning and maintenance.
  • Durable and sustainable....5 pounds of aluminum, plastic, steel, and standard (not proprietary) assembly parts speaks for itself!!

Final considerations, observations and pleasant surprises:
  • At every point of our design project we have been  trying to develop this machine  for a wide market of off the grid coffee enthusiasts and to create what we envisioned as the "ultimate hand coffee grinder".   This process led to considerations large and small over design and convenience and at no point could these considerations allow us to change the central tenet of this machine.... top performance provided by on center absolute alignment of the grinding mechanism.    There is no lower grinds drawer.   The inclusion of a lower drawer would mean the loss of the lower axle bearing or at best an asymmetrical bearing system producing lateral overload on the upper bearing.   The same is true of more conventional bean hopper on top of the machine.....this would compromise the functional design and create the need for a longer top burr axle above the hopper, again creating instability and misalignment, this time with undue forces on the bottom bearing.  All lateral forces are exerted on the upper and lower bearings equally while the burr simply spins....the work of the burr is exclusively to grind coffee beans.  We followed through on some minor embellishments to allow better ease of use but did not vary the central thesis of the design....centered alignment of a top quality burr set.
  • Dosing, bean loading, grinds dispensing all are controlled by the user to his or her personal preference or system....for press we pour directly into a large mouth funnel placed on the brewer....for drip we pour directly into the filter cone and for espresso we pour into a bowl then transfer to filter basket using one of many different dosing scoops or other devices (similar to a drawer approach).  We fully recognize and support the concept that the owner  can and will MOD the grinder.    After a week we have already added our own mods.....a  removable rubber disc cover for the top fill hole we call a  "popper stopper" to prevent the few fly outs at the end of the grind and a "bean ring" which acts as a functional top funnel for the machine.  
And the surprises
  • The burr teeth do not touch, no matter how tightly you set the adjustment nut, there is cutter to cutter touching at any time.  The precise burr alignment means that the only touching of the inner and outer burr occurs at the machined edge of each burr below the fine teeth.  It is impossible to gnash the burrs.
  • The burrs can be easily cleared of residual grinds allowing repeatable setting from coarse to fine and back again with a simple procedure of loosening the burr for free movement and burr clearing, clack the burrs a few times, dump the small residual, and proceed.
  • And last but certainly not least, the PHAROS simply stated SOUNDS BEAUTIFUL when on the grind!   All you hear is the sweet sound of coffee beans becoming ground coffee.....>

    Click here to see the Pharos in action: OE Pharos Hand Coffee Grinder Overview

Click here to see the Pharos in action: Grinding with the OE Pharos Hand Coffee Grinder


By the way, the Pharos of Alexandria was one of the 7 Wonders of the Ancient World, also known as the Lighthouse of Alexandria, it was built on the Island of Pharos, Alexandria, Egypt.



 








As of this writing (09/03/11), numerous changes have been made to the Pharos in response to user input and our desire to make the manufacture of components and assembly process as streamlined and repeatable as possible.  The first Pharos grinders, introduced 04/01/11 had no interior funnel system for grinds dispensing or drilled plate holes for storage of the long bar....these updates were made very simply by drilling the appropriate holes and installing new parts to bring these first grinders up to then current manufacture.   
Continual small tweaks have been made to the hole sizes in the plate system to reduce any possibility of bolt binding which can negatively effect alignment of the burr and currently, we can find no issues to interfere with proper burr alignment, not only when assembled here at OE but when taken apart and reassembled by Pharos owners.
In response to a very good idea by Den of Home Barista dot com, we have added a major overhaul of the grind adjustment system which incorporates two self locking knurled thumb nuts as a stand alone burr set and lock system along with a custom thin jam nut to install the handle independently of the burr set nuts.  As always all Pharos grinders shipped have all upgrades and updates that are available at the time of shipment included.   The upgrade burr set system is available separately as a kit for older Pharos grinders and is installed very easily with no changes required to the machine.....not everyone has an issue with the original burr set system but WE find it to be a logical and useful upgrade...although our prototype Pharos functions perfectly well in the original burr set system (single thumb nut & handle lock system) without the upgrade.

11-2013 Update:

As of Pharos number 853 we have changed the grind setting adjustment system to a more simplified and possibly better single nut system.   We are now using a single split shaft collar nut which has a socket head cap screw for locking the nut onto the treads of the burr axle.   This type of nut has been used in various modifications and as we are making a few small changes in the Pharos it seemed a good time to address the adjustment system as well as a few other aspects of the grinder.


We are no longer using the long pin to hold and set the double nut system but  the single split collar which uses a 9/64" hex key to loosen and tighten the collar nut.   


Above we see the initial handle installation at ZERO setting of the burr.   Note that the handle is installed on the same side as the slot of the split collar.   When dialing in the grinder setting, loosen the hex bolt with the key and move the split in the collar to the opposite side of the axle (180 degrees or 1/2 turn).   Tighten the bolt with the key and the grind setting is at 1/2 turn CCW out giving a setting in the midrange of espresso.


By loosening the bolt and moving in either direction is small increments the grinder burr setting can be "dialed in" for espresso a bit more directly and easily than the double jam nut system (at least that is the general consensus from users of the Pharos with this modification).   There are different hex tools that can be used to tighten and loosen this bolt according to your preference.  We are including a standard "L" key with the machine...you may find other types of tools to be better suited to your needs.   We generally use Bondhus bit drivers or T grip keys, but that is just us....the L tool works fine and can be stored on the grinder frame.
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