Super durable, fast cutting, long lasting and never needs flattening.
Lately there has been much ado over cubic boron nitride (CBN) sharpening systems. CBN grinding wheels for benchtop grinders have been available for some time and have been very well received. But this Spyderco 306CBN is the only CBN benchstone that I’m aware of.
There are several reasons that CBN is worth considering for your next sharpening stone. Most important is that CBN is harder and has greater abrasion, thermal and chemical resistance than either synthetic diamonds (though less so than natural diamond), silicon carbide or aluminum oxide. Unlike other benchtones you can use it dry (without any lubricants). It never requires flattening (though in all fairness neither do diamond stones) and it will sharpen any tool steel, including the S90V produced by Crucible.
At 3″ x 8″ the 306CBN is big enough to handle the largest plane blades and it easily accommodates a honing guide. One side has a fast, aggressive 400-mesh (about 37 micron) and on the other side is a somewhat slower cutting 800-mesh (about 15 micron). You can use the 400-mesh side for flattening the back of chisel and plane blades and for general edge shaping and maintenance. Use the other side to refine the edge.
I used the 306CBN on a range of O1, A2 and PM-V11 chisel and plane blades, and was very pleased with its performance. I found that both sides of the 306CBN cut noticeably faster than equivalent diamond stones. The 800-mesh produces a very fine finish indeed that you can go straight to work with. However, if you like to put a mirror finish on your cutting tools, you’ll want to move to a finer grit stone such as a 6000- or 8000-grit diamond stone. Obviously, this is an initial impression – only time will tell how well a CBN benchstone performs. But I’m very enthusiastic about the results so far.
The 306CBN is comparable in price to a monocrystalline diamond-coated sharpening stone. It offers much better value than a waterstone in that it’s harder, more durable, lasts longer and will never need to be flattened. And you’ll get back to what you enjoy more quickly – working wood.