150 mm CBN grinding wheel 500 Grit
CBN Grinding Wheel.
Boron Nitride is a ceramic material with a hardness approaching that of diamond. Cubic Boron Nitride grinding wheels (CBN wheels) are ideally suited for sharpening HSS, the harder "Pro PM" and "2060 steel" grades, as well as hardened M42 steel. Carbon steel can also be sharpened very effectively with CBN wheels.
Very little pressure is required during grinding, heat generation is minimal, there are very few sparks, and the grinding results are outstanding. Another major advantage is that the surface of the wheel always remains perfectly flat. No more breathing grinding dust because your grinding stone needs dressing again! For most woodturners, a CBN wheel will last a lifetime.
The grinding wheels are available in diameters of 150, 200 or 250 mm. The width of the CBN wheels is 40 mm. Please select the correct shaft diameter for your grinder from the drop-down menu.
To mount the wheels, a shaft length of at least 38 mm is required (retaining washer – grinding wheel – retaining washer – nut). This makes it possible to mount a 40 mm wide wheel even on a relatively short shaft.
CBN Grinding Wheel on the Lathe
Sharpening on the lathe is not an unusual practice among woodturners. Before starting a project, or during turning, many woodturners simply mount a grinding wheel on the lathe and give all their tools a quick touch-up. For this purpose, we now offer a dedicated accessory: the CBN Grinding Wheel Adapter.
On this page you will also find the other components of the CARP SH sharpening system.
Try?
If you want to try the CBN grinding wheels, contact me and take your tools with you!
Important information for use:
1 - Do not apply pressure to the wheel
Do not apply additional pressure to the tool being sharpened. The weight of the tool itself is sufficient. Excessive pressure can cause damage to the grinding wheel due to heat build-up. (The CBN crystals begin to change shape slightly at around 400°C, but actual damage does not occur until approximately 1400°C. For comparison: a diamond wheel can already suffer damage at around 700°C.)
2 - Speed
A grinding wheel with a diameter of 150 mm performs best at speeds between 1700 and 3000 rpm.
A grinding wheel with a diameter of 200 mm performs best at speeds between 1400 and 2100 rpm.
A grinding wheel with a diameter of 250 mm is suitable for speeds up to 1450 rpm. These wheels are particularly suitable for use on slow-speed grinders such as the Tormek T7 and Tormek T8.
3 - First use
When using a CBN wheel for the first time, the grinding pattern may appear somewhat aggressive. After sharpening a few tools, this effect disappears. Don't worry! From that point on, the CBN wheel will produce a consistent grinding finish for a very long time.
CBN Grinding Wheels
A few years ago, after giving a demonstration, I was given a damaged CBN wheel by the manufacturer. The thought of the noise that would result from pressing a steel tool against a metal grinding wheel was enough to leave that wheel sitting in the cabinet under my grinder for several months. Once I finally mounted it, however, it never came off again. (And that dreaded noise turned out to be barely noticeable...)
What is CBN?
CBN stands for Cubic Boron Nitride. It consists of cubic crystals of the ceramic material boron nitride. The material was originally developed by General Electric. Experiments with CBN were already being carried out in the 1950s, and it was introduced commercially in 1969. It was revolutionary! In the applications for which GE developed it, CBN lasted much longer than diamond. As a result, CBN abrasives were initially even more expensive than diamond. Nowadays, however, thanks to large-scale production—particularly in China—the price has become much more affordable, although it remains an expensive material.
Why use a CBN grinding wheel?
CBN wheels are exceptionally well suited for sharpening HSS and harder steel grades containing cobalt. Very little pressure is required during grinding, heat generation is minimal, there are very few sparks, and the grinding results are outstanding. Another major advantage is that the surface of the wheel does not wear. No more grooves, hollows or uneven spots in the wheel surface. And no more breathing grinding dust because your grinding stone needs dressing again! For most woodturners, a CBN wheel will last a lifetime.
What grit should I choose?
The standard grit size for a CBN wheel is 120 grit. There is also a fine version with 280 grit. If I had to guess the grit size purely from the sharpening results, I would have estimated them to be much finer. The standard grit produces an exceptionally clean cutting edge. Whenever I sharpen one of my skew chisels, I still cannot resist shaving a few hairs off my arm just to test the edge...
The 250 mm wheels are available with 280 grit and 500 grit coatings. These wheels are also balanced, but they were primarily developed as replacements for the stones on slow-speed wet grinders. For that application, I find the standard grit somewhat too coarse.
What speed should my CBN wheel run at?
The wheels are balanced, just like the wheels on your car, so that they run smoothly even at higher speeds.
CBN wheels perform best at the following speeds:
- 150 mm wheel: between 1700 and 3000 rpm
- 200 mm wheel: between 1400 and 2100 rpm
- 250 mm wheel: between 900 and 1400 rpm
In general, a CBN wheel becomes more efficient as the speed increases, up to the limits mentioned above.
The often-heard claim that a CBN wheel does not work properly on a slow-speed grinder is simply incorrect. A CBN wheel on a Tormek sharpens just as well as a CBN wheel on a high-speed bench grinder; it simply takes proportionally more time to achieve the same result.
Tormek
A slowly rotating CBN wheel, such as one mounted on a Tormek, really does sharpen just as well as a CBN wheel running on a 1450 rpm bench grinder; it simply takes proportionally longer to achieve the same result.
As mentioned earlier, the 200 mm and 250 mm wheels were specifically designed for use on the Tormek and other slow-speed wet grinders. They work extremely well, although there is one small annoyance. During sharpening, the tip of your tool will always become slightly magnetic. Normally this is not a problem, because the higher speed of a bench grinder throws the metal particles away. However, because the wheel speed on a Tormek is so low, you may need to wipe the magnetic particles off the cutting edge with a cloth after sharpening. Placing a magnet underneath the grinding wheel also works wonders.
Important: If you mount a CBN wheel on a slow-speed grinder, do not use water. CBN wheels are designed to be used dry.
Sizes
The CBN wheels are available in diameters of 150 mm, 200 mm and 250 mm. All wheels have a width of 40 mm.
The bore diameter is always 32 mm. Reducer bushes are supplied to adapt the bore to the most common shaft diameters, namely: 12 mm, 12.7 mm (1/2"), 15 mm, 15.8 mm (5/8"), 16 mm, and 20 mm.
An adapter is also available that allows you to mount the wheel directly onto the spindle of your wood lathe. This enables you to choose your own grinding speed!
Can it break down?
Yes! If you drop a wheel on a concrete floor it can break or deform it. If you exert too much pressure on the wheel, the CBN granules can deform slightly as a result of heat development, which will decrease performance. This happens only from 400 degrees. (For info: At a diamond wheel that is already from 170 degrees) If you want to try the CBN grinding wheels make an * appointment * and take your chisels with you! In my workshop is a 200mm CBN wheel running on a large grinding machine for a few years now and a CBN wheel on a Tormek.
Other applications
CBN coatings are also used on honing tools. In this application, the finest grit sizes are used. They are available both as a rod and as a flat surface. I use the flat surface for my skew chisel, and the two rounded edges for my spindle gouge and small bowl gouge respectively.
Well... this has turned into quite a long story and, for many people, perhaps a bit of a boring one, but I hope someone will find it useful.
If you would like to try working with a CBN wheel yourself, just give me a call or send me an email. And don't forget to bring your tools!
| diameter | 12 mm or 12,7 mm or 20 mm or 15 mm or 15,8 mm (5/8 Zoll) or 16 mm or 32 mm |