Coffee Cup
"Espresso! My Espresso!"
An Ongoing Internet Novelette
by Randy Glass - Copyright 2007 - All rights reserved

Coffee Cup
89
Grindmaster Commercial Grinder
Model 500

      When it comes to commercial coffee grinders for retail use, there are few (if any) other names that come to mind other than Grindmaster. Still in business today, Richard Schulman founded the Grindmaster Corporation with his own line of patented coffee grinders in 1933. You see their equipment in places like Costco, Trader Joe's, and so many other stores, placed for the convenience of their patrons who prefer whole-bean coffee, but who have no coffee grinder at home. These large, powerful grinders often receive little care other than making sure they are plugged into the outlet. Often placed in pairs— one for flavored coffee and one for coffee with no flavor... errr, no flavor added to the beans. I have often looked down into the loading bin for these grinders, and can depend on them being caked with old coffee beans, grounds, and oils. As disgusting as that all sounds, it is a testament that these Grindmaster grinders are made to take abuse and last through thousands of pounds of coffee. If just ten patrons a day grind one pound of coffee each, over a ten year period, one of these grinders can process upwards of 15 tons of coffee!

      It has been about nine years since my brother came up from So. Cal. (I have been down visited him three or four times). It may have been guilt; it may have been a shortage of storage space in his garage— whatever his motivation, he brought me a gift:

      And what a gift it is! Fifty pounds of coffee grinder that can go through a pound of coffee in just a few seconds. He carried it into my garage and placed it on my workbench. Of course I plugged it in right away, pushed up on the activation switch, and it worked! He laughed commenting that he had procured it as a display piece, that since he bought it he had never even plugged it in!

      The next morning I disassembled it and gave it a bit of a cleaning. Here's what lies inside one of these behemoths:

      Remove four Phillips screws and the entire top just lifts off. With its red top removed, we are looking down into the machine. The front face of the grinder is towards the bottom of the picture. On the left, the large gray cylinder is the motor— rated at 7 amps and 1/3 horsepower, it is made for some serious work. The opening in the middle is where the beans are funneled into the grinder, and you can plainly see the feed auger which is part of the powered, outer burr. The assembly on the right is the grinding chamber and grind adjustment mechanism. The motor sits on a heavy-gauge steel pedestal, and the grinding mechanism bolts to the motor.

      Here is the "outer" burr which is spun by the motor. You can see that it is one piece, and includes the feed auger.

      On the right side of the machine (viewed from the front) is an access panel held on by two screws. Removing this reveals the grinding chamber. The machine was made to be easily maintained. The cover of the grinding chamber is held by two wing bolts (bolts with wing nut style ends, seen in the previous image). Once these are removed, the fixed burr (seen here) is easily accessed. In the center is the motor shaft— the flat faces on the end of the shaft engage the outer burr.

      This is the adjustment mechanism. The lever and knob protrude through the front of the machine and engage indexing slots on the face of the machine which are labeled with grinds, from perc to espresso(!). Moving the lever rotates the adjustment plate which turns a screw mechanism inside (not shown here). The nut in the center can be loosened and the range adjusted by means of the center screw.

      On the outer face of the powered burr there is a metal cap that looks like the silver top of an old style, floor mounted, high beam switch. This spins with the burr. On the inner side of the adjustment mechanism is what appears to be a carbon button (seen here) which moves in and out through the motion of the screw adjuster mentioned above. This button presses against the outer burr, forcing it closer to the fixed burr. There is a spring between the burrs which holds the two burrs apart, and pushes the burr outwards when moving to a coarser setting.

      After giving it a cleaning, replacing some old gasket material used to seal the bean path, and replacing the old, hard-as-rocks rubber feet, I roasted a batch of sweep and ground a handful at each of the settings. And it really works quite well, and quite quickly! I have moved it into the house, ready to grind coffee for friends. It will also come in handy when my dedicated espresso grinder arrives. I can use this monster to grind for a pot of drip without disturbing the setting on the stepless, commercial espresso grinder. And besides— it just looks cool!

      Just how fast is this thing? I roasted a batch of sweep to test it.

ROASTED WHOLE BEANS:
  8.3 oz.     (235 g)
  3.5 cups   (.75 L)

DRIP GRIND TIME
  30.28 seconds

COFFEE AFTER GRINDING
  approximately 232 grams (a bit under 3 grams total loss)

That equates to 7.76 grams per second or a pound is a fraction under one minute at the drip setting.


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