Direct Drive vs Drive Shaft

The most common drive setup for a belt grinder is a pair of bearing blocks which supports the drive shaft with the drive wheel on one end and a single or step pulley on the other, like our Mod-3 grinder. The motor is then connected with a V-belt to the motor pulley. This has the benefit of being very flexible when it comes to motor choices, and with a pair of step pulleys it makes a simple low tech way to get rudimentary speed adjustment. This is usually the cheapest motor setup, and for this reason a very popular choice among knife makers and blacksmiths.

The downside is that you pay a significant price in power and performance. All of the extra components (two bearings, two pulleys and a V-belt) add a significant amount of extra friction, reducing torque by an incredible 30-40%! That means the big awesome 2HP motor you bought will only effectively be a 1.2 HP motor when compared to a 2HP direct drive motor. (What a bummer.) And that’s assuming your using 220v for that motor, if your only using 110v then you drop to 1.5 HP, which means it’s equivalent to a 0.9 HP direct drive motor. (Ugh, that just sucks.) As if that’s not bad enough, (wait, it gets worse?!) all those extra linkages add places for vibrations and misalignments to creep in, taking your smoothly running grinder and downgrading it yet again.

For these reasons, we have decided to only sell direct drive motors with VFDs for our complete machines, but we understand that for many the cost is too great. For that reason we offer the Mod-3 grinder chassis as an entry level option.