This simple sharpening set from Rockler could save you loads of time and money! Click image to enlarge

Hollow Chisel Sharpening Set

Easy touch-up tools from Rockler

Text & Photos by Tom Hintz

   Hollow chisel mortisers have made mortise and tenon joinery a far easier task. Since getting my machine, I use this beautiful and strong joint in more projects because I can make them easily and accurately.
   For many, the down side to these machines has been replacing the chisels when they grew dull. This reasonably priced sharpening set from Rockler makes it easy for you to touch up the cutting edges on the hollow chisels to restore their performance.

Initial Impressions

   Rockler's 3-Piece Sharpening Set almost looks too simple to be effective. A pair of cone-shaped cutters encrusted with diamond chips and a handle makes up the whole thing. As it turns out, that's all you need.
   The components of the Rockler kit appear well made, an impression that was proven correct after considerable use in the shop.

Cutters

The 220-grit (left) and 600-grit (right) diamond encrusted cones combine to make short work of touching up your moritser chisels. Click image to enlarge

   The cone-shaped cutters are based on a 60-degree angle that seems to be universal in hollow chisels. A 220-grit cutter is used to "rough out" the cutting edge, removing gouges or other surface irregularities. The 600-grit cutter then smooths the surface and refines the cutting edge. The cutters are designed to work with chisels up to ½".
   Both cutters have a ¼" quick-change shank that allows them to be used in most quick change chucks as well as the included handle.

Handle

   Included in the set is a nicely shaped handle that is large enough to get a good grip on but contoured to be controllable and comfortable. A quick-change chuck makes installing or changing cutters in the handle fast, simple but secure.
   The chuck makes the handle compatible with virtually any ¼" quick-change bit you might have.

In the Shop

Whether used by hand or in a cordless drill on low speed, the Rockler set makes short work of sharpening hollow chisels. Click images to enlarge

   Though I use my hollow chisel mortiser frequently, the chisels have never been sharpened and the ¼" and 3/8" versions were getting pretty dull. I was going to buy new ones but saw the Rockler kit and decided to give it a try. This turned out to be another of my totally accidental but very good decisions.
   After trying the 220-grit cone in the supplied handle with surprisingly good results, I opted to chuck the cone up in my Bosch cordless drill, set on the "Power" range to keep the RPM down. The package warns against exceeding 250 RPM so the drill press is obviously out.
   Even turning very slowly in the cordless drill, the 220-grit cone cleaned up my badly dulled chisels very quickly. After 20-seconds or so of low-speed, minimal pressure grinding the cutting edge looked much better and felt sharp. After changing to the 600-grit cone, the chisels were given another 20-seconds of "honing" and looked even better. Moreover, the edges

The "Before" (left) and "After" (right) photos show a remarkable change after a total of 40 seconds of work. The chisel cuts even better than it looks. Click images to enlarge

felt sharper yet.
   I noticed that before and after sharpening, all of my hollow chisels had a noticeable burr on the outside of the cutting edges. I suspect this naturally rolls over during the mortise cutting procedure. I used a fine, flat diamond card to lightly rub those burrs away to finish sharpening them.
   When the freshened chisels were installed in the machine and put to wood, the value of this kit became evident. My old, ready-to-be-replaced chisels cut as good as when they were new: maybe better. The effort on the mortiser handle seemed to be less than I remember and the sides of the mortises came out smooth and clean. The chisels also showed no tendency to wander or deflect.

Conclusions

   The Rockler 3 Piece Sharpening Set (Rockler #24727) for hollow mortising chisels is well worth the price of $19.95 (5-18-2005), especially if you consider the cost of replacing one chisel. If you can extend the life of even one chisel, you save money. So far, I have extended the life of all my chisels at least twice. That makes the Rockler Sharpening Set almost as good as found money.

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