Academy Notes and Tips
the Shopsmith Woodworking Academy
The Jointer, Molder and Shaper share a common capability; they're all milling tools the average woodworker can use to shape and condition the edges and surfaces of workpieces.
However, they also share a common problem -- rapid edge dulling. All of them use triple element cutters. As a result, whenever you use one of these tools, each edge is brought into contact with the stock many, many times as it rotates at high speeds. And, as you might expect, with only three edges, they tend to dull quickly and must be kept as sharp as possible to achieve the smoothest edges.
To refresh your memory once again, the safest operations and best results come from using SHARP tools. Dull edges not only have an adverse effect on your results, they can also be very dangerous when in use.
TO HONE OR TO GRIND? - THIS IS THE QUESTION
The answer to this question is really quite simple. If your cutter is dull and the edges are free of nicks, the best solution is honing. In other words, If it ain't broke, don't fix it! Remember, the process of sharpening tools always results in the removal of steel from the edges and you can only sharpen the edges of cutting tools so many times before you eventually run out of material to remove. Therefore, edges should only be ground to eliminate nicks or solve other serious problems...grinding should be held to a minimum.
Actually, it's not difficult to get these tools good and sharp using a set of bench oilstones. Honing Jointer Knives is often no more than touching them up while they're still mounted on the machine. If they're nicked and need to be re-ground, we'll tell you how to do this in a minute.
Shaper and Molding Knives can also be honed quite easily on an oilstone. However, regrinding Shaper and Molding Knives to remove deep nicks is a task that's best reserved for a professional, since each of the three cutting edges must be ground to match perfectly in order to produce the best cuts without vibrations.
It's important to note that the honing process for all three types of knives requires a well-dressed, flattened stone and enough lubricant to keep the stone from loading-up with swarf during sharpening. While you might think about using a waterstone to hone Shaper and Molding Knives, keep in mind that the water required for lubricating such stones will rust your Jointer table and mechanisms. For this reason, it's best to use Oil Stones such as a Hard Arkansas Stone for this on-the-Jointer process. So, let's start with honing the Jointer Knives.
The Jointer is, in itself, a multi-purpose tool used to prepare straight, square edges on boards; to surface the faces of narrow stock; and to create tapers and rabbets. The smoothness of the Jointer cut depends on the speed of the Knives or Cutterhead, the rate of feed, the proper setup...and, of course, the sharpness of your Jointer Knives.
Honing the Knives
on the Jointer
CAUTION: Before performing any maintenance on your Jointer, be certain the power source is disconnected, not merely turned off!
Start by removing the guard and fence so you can remove the built-up pitch from the Knives with paint thinner or Saw Blade Cleaner.
IMPORTANT: Do not allow Saw Blade Cleaner to come into contact with bearings.