Tech Support & FAQ

We’re working on a FAQ and other resources — coming soon!

The KMG was intentionally designed so that the motor was not an integral part of the machine which allows for unlimited choices in how the grinder is powered. This allows you the use just about any type of motor and it also allows to set the grinder up with different speeds by changing the pulley ratio between the motor and grinder. We prefer to drive the KMG with pulleys and a a belt to maximize the versatility, however you can also direct drive with a motor coupling of your choice. Typical motor sizes for the KMG can be from 1-1/2 to 5 hp.
We always recommend a grinder package such as the KMG-8 or KMG-10 that includes both, a contact wheel, and the platen attachment. These 2 attachments will be used constantly in your shop. The 8″ and 10″ wheel are equally popular and purchased on personal preference. A work rest is included.
With the standard 4″ drive wheel, the abrasive belt speed is easily calculated as follows:
Belt speed (ft/min) = RPM (example: 100rpm= 100ft/min, 3500 rpm= 3500ft/min)

The KMG Grinders are proudly built from unplated and unpainted steel. If you wish, you can customize the  grinder by plating or painting the exposed metal surfaces, but in  our shop, we care for the grinders simply  with a coat of light oil and a Scotch Brite pad to scour away dirt and small scratches.

8” vs 10” wheel:
This is a great question and is usually decided by personal preference. Since the belt speed is the same regardless of the size of the contact wheel, there is no performance differences between the sizes. The only difference is the shape of the hollow grind caused by the wheel. Because the 10” has a bigger radius, the hollow grind is more shallow and taller than what an 8” wheel would produce. The 10” wheel is much more popular. However, there are many customers who prefer the 8” wheel for it’s smaller size, lower cost, and deeper hollow grind.

3 speed –vs- Variable speed:
The KMG was specifically designed so that the motor was not an integral part of the grinder. This allows for unlimited choices on how it might be powered. Simply spinning the drive shaft makes the grinder run.
The step pulley system allows 3 speed choices, fast, med and slow. The 4”, 3” 2” pulley is used because the centerline distance between the motor shaft and grinder drive shaft is the same for each belt position. This eliminates the need to re-adjust the motor position for each speed change. You simply roll the belt from on groove, to the next smaller size by hand, like a derailleur on a bicycle. Speed changes are done in a few seconds without tools. The grinding belt speeds produced are approximately 3800, 1800, and 900 feet/minute. Through research, these speeds are all very practical and usable speeds for tasks like custom knife making.
Variable basically allows an infinite selection of speed from 0-100%. It can be changed on the fly without stopping and allows the user to adjust for more grinding control and precision based on personal preference and feel. Comparing to the 3 speed set-up, the highest belt speed can be about 10% faster due to selections in the motor’s speed control (VFD), or about 4200 feet/minute. The speed range is infinite from full speed down to zero.

Install and Set Up Instructions and Diagrams:

KMG Packages

Variable Speed set up

The most common problem that we see during initial setup is wiring at the motor.  There are 9 wires and it is easy to get them out of place.
Double check there.  You should have the following connected:
t4,t5 and t6 all connected together with a yellow wire nut.
t1,t7, red
t2, t8 , white
t3,t9 black
At the controller(VFD)  if you are running it on 220V…make sure the input power jumper is on “230”.   If you are running it on 110V….make sure the jumper is on “115”
If you are using 220V input, use a voltmeter across L1 and L2 on the VFD’s terminal strip to verify that you do in fact have 220.  This is the second most common issue that we see.
(If you are using 230, you will not use the neutral. Make sure to ground to the case, and run the two hot to the L1 and L2 terminals)

Set Up Instructions for  Variable Speed

Layout Diagram for Variable Speed

Set Up Instructions for 3 Speed

Assembly Diagram for 3 Speed

Tips for Tracking and Tuning Adjustments



Schematic for Extension Plate


Installation instructions Forward/Stop/Reverse switch for our variable speed controllers

Set Up Instructions for Switch Kit for 110089 1-1/2hp motor

Set Up Instructions for the 110089 Motor




Information about the 3 Speed KMG