Testing CBN Grinding Wheels – FineWoodworking

1 May 2025 Stan

Synopsis: CBN wheels for bench grinders have become popular among wood turners, whose tools tend to be made with high-speed alloys that are tough on traditional wheels. Chris Gochnour wanted to know if CBN wheels could be used to sharpen chisels and plane blades, which are typically made from softer steels. He was concerned that these softer steels would stick to the CBN wheels, possibly ruining them. In tests using both a traditional grinder and a Tormek grinder, Gochnour found CBN wheels to have all the benefits of traditional wheels, with none of the downsides.

I have a wood-turning friend who teaches an occasional class at my Salt Lake City workshop. He brings a number of bench grinders with him each time, which are equipped with CBN wheels. These work beautifully on turning tools, which tend to be made with high-speed alloys that are tough on traditional wheels.

CBN stands for “cubic boron nitride,” an industrial abrasive that’s second only to diamond in hardness. The CBN particles are electroplated onto a steel or aluminum wheel, and they have an almost unlimited lifespan for woodshop use. Unlike traditional molded grinding wheels, CBN wheels run perfectly true and never have to be dressed, a process that reduces the size and longevity of a traditional wheel. That means you won’t have to adjust your tool rests to accommodate a wheel that gets smaller over time. It also means you don’t have to fuss with wheel dressers.

Author showing the edge of a chisel has zero burning. — **Smooth and cool.** CBN wheels run true and smooth, and they make it nearly impossible to overheat edges and remove their hardness. Even the finer-grit wheels remove material rapidly.

I had also heard that CBN wheels cut faster than traditional wheels. Perhaps most importantly, they were also reported to run cooler than their old-school counterparts, which can overheat tool edges, removing their hardness and temper and forcing you to grind past the damaged area to get back to hardened steel.

Being primarily a furniture maker rather than a wood turner, I was interested to find out how these new wheels would fare with chisels and plane blades, which tend to use slightly softer steels than turning tools. Those materials include 01 steels, the type used in traditional woodworking tools; tougher A2 steels; and PMV-11, a proprietary powdered steel used exclusively in Veritas tools, sold by Lee Valley.

My worry, however, which was shared by my wood-turning friend and others, was that these slightly softer steels would stick to the CBN wheels, clogging (or “loading”) their abrasives. If there were no way to dress them and expose fresh abrasive grains, as with traditional wheels, the CBN wheels would become less effective, and possibly even be ruined.

Now, based on my own testing and that of others, I can confirm that this worry is unfounded, which leaves woodworkers free to enjoy all the benefits of these exciting new wheels.

The bottom line is this: After 35 years as a professional woodworker, I’ll be changing my grinding wheels to CBN.

Sorting through the many options

To help me better understand CBN technology and its capabilities, I collaborated with Ken Rizza, the founder of Wood Turners Wonders (WTW), one of the leading retailers of high-quality CBN wheels. Rizza has a number of helpful videos on the company’s website (woodturnerswonders.com), which convinced me that these wheels might work just as well on traditional tool steels as they do on more exotic alloys.

CBN wheels are sold in a variety of shapes, sizes, and grits, so my first step was deciding which ones to try. Rizza helped me identify best bets.

CBN wheels are pricier than traditional grinding wheels. For example, my favorite for a standard bench grinder costs about $160, compared to $50 or $60 for a high-quality traditional wheel.

My goal was to settle on the one wheel that would work best on a common bench grinder, whether slow-speed (roughly 1,725 rpm) or standard (3,450 rpm, more or less). I did that, and then did the same for my Tormek grinder.

Testing reveals big benefits

Woodworkers aren’t always aware of this, but traditional molded wheels are often out of true side to side and become somewhat oval in shape with repeated dressing, which makes them out of true front to back as well. This creates vibration in both directions, making grinding rougher and less efficient.

A CBN wheel is machined, on the other hand, and therefore runs true (as true as your grinder does anyway). As a result, the face of a CBN wheel feels like a solid surface in use, and the tool feels very steady in your hand. That also makes grinding more efficient. This is partly why the CBN wheels beat my traditional wheel on raw grinding speed, despite their big differences in grit sizes.

After the speed test, I was leaning toward the 180-grit CBN wheel, so I took the edges that I ground on that wheel to my waterstones for final honing and found that I could skip the first stone I usually use and jump right to my 1,000-grit stone, with no loss in honing efficiency. This is a big benefit for hand-tool users. As for burning, it took just eight seconds of continuous grinding on my traditional wheel to begin to darken the steel at the tip of the tool. On the 180-grit CBN wheel, I ground continuously for a minute, with no sign of darkening and burning. The tool became too hot to hold at that point, but there was still no burning present.

This virtually eliminates the main danger associated with traditional grinding wheels. You won’t have to grind with such a feather-light touch on CBN wheels, and you can probably get rid of your little cup of water too, the one you dunk the tip of the tool in every five or 10 seconds to keep it from burning.

During the few months I’ve been using the CBN wheels, I can’t say that I’ve noticed any significant loading of metal between the abrasive grits. I did load up the wheel with Slick-Stick, however, when I applied it too liberally. But it’s easy to scrub off.

They work just as well on Tormek grinders

The Tormek was the first grinder of its kind, but there are a number of similar systems on the market. They feature a wider, finer-grit wheel that runs through a water bath at a very slow speed, ensuring that it won’t burn tool edges.

Tormek-style machines also have a handy tool holder built in, which holds chisels and plane blades at a fixed angle for effective sharpening. They include a leather stropping wheel, which can put a finely honed edge on a freshly ground tool, making the system an all-in-one sharpening solution. That said, some woodworkers prefer to use the grinding wheel only and jump to flat stones (usually waterstones) for honing.

To make sure we had all our bases covered, I ordered Tormek-style CBN wheels in two grits, 200 and 600, and compared their performance to the standard Tormek wheel.

Wood Turners Wonders recommends that its CBN Tormek wheels be used dry, or at least dried off after each use, to prevent corrosion of the abrasive material. I used the wheels both ways and found no advantage to running the wheels wet. Further, I did notice mild, orangey oxidation when I left the wheels wet after use.

I did the same speed test with the Tormek wheels that I conducted on the bench-grinder wheels, marking a line on the top edge of a chisel and measuring how long it took to grind to the line. The 600-grit CBN wheel removed material 20% slower than the 200-grit CBN wheel, but twice as fast as the Tormek wheel.

A few more tips

Tame the wobble. CBN wheels are machined, not molded like traditional wheels, which helps them run true, avoid vibration, and grind more efficiently. But that only works if your grinder runs true. These nesting washers will self-align to help a CBN wheel run true on a wobbly arbor.

Closing thoughts

Used correctly, a bench grinder offers the fastest way to create a fresh bevel. If you’ve had bad experiences with bench grinders in the past, a CBN wheel will give you all of their benefits without the downsides. And unlike traditional grinding wheels, CBN wheels don’t need to be dressed, saving you even more time.

—Chris Gochnour is a contributing editor to FWW.

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