by Megan Fitzpatrick
We’ve been using Norton 3X Super Cool ceramic alumina oxide wheels on our dry grinders since we first reviewed them in 2006; they cut fast and don’t easily overheat a tool’s edge – that means you can get your heavy grinding done fairly quickly, because you don’t have to stop and cool the tool in water or oil every few passes. But they need regular dressing to deglaze them and to keep the wheel slightly crowned.
The new crowned cubic boron nitride (CBN) wheel from Tools for Working Wood, which has the abrasive bonded to a machined aluminum wheel, runs even cooler. The metal plate absorbs much of the generated heat (I had to grind aggressively and for more than 30 seconds to get a blade hot enough to need dunking). And, because the wheel comes crowned out of the box, there’s no need to dress it for shape – or at all. If used only for ferrous metals as recommended, it won’t glaze. I tried it on about 10 chisels and half as many plane blades, both for grinding off chips and large secondary bevels, and for reshaping the cutting edges of a plane blade. I had good results on O1, A2, high speed steel and PMV-11. (Bonus: It’s impossible to engage in the dangerous practice of side-grinding on this wheel.)
At the time of this review, the 3⁄4″-wide wheels, available in #60 and #80 grit, were available only in 6″ diameters, and fit a 1⁄2″ arbor. To use it on my 8″ grinder, I simply had to modify the tool rest by adding a wood block. Now, 8″ wheels are available. Getting the wheel on and off is a bit difficult; I had to basically thread it (and dethread it) while holding the shaft with pliers. That’s a bit annoying, but.…
This CBN grinding wheel costs about twice as much as the Norton 3X; what I can’t tell you (yet) is if it will last twice as long. Stay tuned.