GPX (and GPC) Support

The GPX and its variants the DC, WCI, and T are some of the most widely used industrial grinders in the world. Because of their popularity, it is not uncommon for customers to seek support for many of the same issues over the lifetime of grinder ownership, which are compiled here.

These videos provide expert help for common GPX support issues. Much of the principles of design are similar to the GPC as well. If you are a GPC owner, the troubleshooting and maintenance are nearly identical.

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How to Replace Discs

Dechaffing Gate Explained

How to Clean a GPX

How to Calibrate a GPX

Proper Use of the Dechaffing Gate

How to Replace the Dechaffing Gate

Testing Voltage on Single Phase GPX

Testing Voltage on a 3 Phase GPX

Changing an Overload Relay on a GPX

Common Issues

Grinder Shuts Off Randomly Make sure the right voltage is getting to your grinder. If the voltage is too low, the motor draws more amps than is allowed by the overload relay inside the power box. You can use a multimeter to measure voltage and a clamp meter to measure amperage. For reference, the overload relay setting on a GPX should be the following:

220 V single phase model, this limit is set to 19 A
220 V 3 phase model, this limit is set to 12 A
380 V 3 phase model, this limit is set to 6 A
460 V 3 phase model, this limit is set to 6 A

For a GPC model the limits are different. Call us if you need the limits on your GPC overload relay.
The Rotor Isn’t Coming Off the Shaft There are two screws (1/4″ 20 Thread screws at 2.5″ length) you can put inside the rotor insert to safely dislodge the rotor from the shaft. Because the tolerance between the rotor insert and shaft is very tight, over time the shaft’s end may wear and create high points. Use a file to level out the shaft’s edges until the rotor can fit and release easily from the shaft.
The Grinder Is On, but Hardly Any Coffee Is Coming Through the Grinder and Is Very InconsistentYour 3 phase motor may be wired in reverse. Swap any two of the three wire leads (typically on the NEMA plug, if that’s installed). Do not swap the ground wire though (typically green). Swapping any two of the three wires will reverse the direction of your 3 phase motor. However, this will not work for single phase motors. If you have a single phase motor, the motor will always run in the correct direction.
Coffee Is Shooting Out of the Grinder Spout Unusually FastCheck your dechaffing gate. Is it broken or bent?
My Grind Setting Is Changing During GrindingIs your locking nut missing? Sometimes it falls off and customers may forget it exists to lock the dial in place during grinding.
Should I Add Grease to My Motor?The bearings inside the GPX and GPC motors are sealed. Meaning, even if you add grease to the motor through the grease fittings, the grease doesn’t have anywhere to go. There’s no need to add grease to your motor.
Why Is My Grinder’s Amperage Overload Protector Tripping?Your grinder may not be getting the proper voltage from your power source through all of the leads. You’ll want to test this with a multimeter.
Can I Replace the Motor?While in theory the motor can be replaced, we never recommend this as an in-field repair. The burr housing is attached to the motor perpendicular to the motor shaft within a 0.001″ tolerance (about 25 microns), which requires special instrumentation.

Manuals for GPX models