CBN Grinding Wheel.
Boron Nitride is a ceramic material with almost the hardness of diamonds. Cubic Boron Nitride Grinding wheels (CBN wheels) are extremely suitable for grinding HSS and the harder “pro PM” and “2060 steel”. There is hardly any force on the discs to be exerted, there is only little heat development and sparks and the grinding result is stunning! Another great advantage is that the surface of the wheel does not wear out! So no more dust because your grinding stone must be made flat again! For most wood-turners, a CBN wheel will last a lifetime. The grain of CBN wheels is extremely suitable for grinding woodworking tools. The wheels are balanced so that the grinding machine can run beautifully stable. The CBN wheels can be obtained in 150 mm, 200 mm and 250 mm. The width is 40 mm. The hole is 32 mm. Choose in the pull down menu the size of the spindle of your grinding machine. The wheels need 25 mm width at the spindle so you might nee shims there.
If you want to try the CBN grinding wheels make an contact me and take your chisels with you!
Important information for use:
1-do not exert pressure on the wheel. Do not use extra pressure on the chisel that you sharpen. The weight of the chisel itself is sufficient! Too much pressure can lead to damage to the grinding wheel due to heat formation. (The granules change a bit of shape at 400 degrees Celsius, real damage only occurs at 400 degrees Celsius. (For comparison: A diamond stone already creates damage at 170 degrees)
2-speed: A grinding wheel with a diameter of 150 mm works best at a speed between 1700 and 3000 rpm. A grinding wheel with a diameter of 200 mm works best at a speed between 1400 and 2100 rpm. A grinding wheel with a diameter of 250 mm works best at a speed up to 1450 rpm. You can use these wheels on slow running grinders like e.g. the Tormek.
CBN Grinding wheels.
A few years ago a damaged CBN wheel was given to me by the producer. Due to the thought of the sound that would arise if I were to hold a steel chisel on a metal grinding disc, the grinding wheel was located in the box under the grinding machine for a few months. Once I put it on the machine it never got off. (that dreaded sound was not there…)
What IS CBN?
CBN means Cubic Boron Nitride. They are square grains of the ceramic material Boron Nitride. A material developed by General Electric. In the years 50 they were already testing with it and in 1969 it was put on the market. It was revolutionary! It did last much longer than diamonds! The grain was initially much more expensive than diamonds. But because the material is now produced in larger quantities (and especially in China) the price is comparable to gold. It remains expensive stuff so.
Why a CBN grinding wheel?
CBN wheels are extremely suitable for grinding HSS and the harder steels with cobalt additions. There is hardly any force on the discs to be exerted, there is little heat development, little sparks and the grinding result is stunning! Another great advantage is that the surface of the wheel does not wear out! So no more dust because your grinding stone must be made flat again! For most wood-turners, a CBN wheel will last a lifetime. What kind of grain does such a CBN wheel? The standard “grid” on a wheel is similar to about grain 120. I also have a 280 grit version. If I were to gamble on the basis of the sharpening result though, I would have estimated the grain coarseness much higher. The standard grid gives a fantastic tightly cut crease. When I have grinded my skew again I can never resist to shave, for a test, some hair from my arm… The wheel with a diameter of 250 mm I have only in 280 grit. This wheel is specially made to replace the stones of a wet grinder. I find the standard granule slightly too coarse.
At what speed should CBN wheels run? The wheels are balanced, just like a wheel to your car, so that they do not cause vibrations at higher revs. CBN wheels perform best at the following speeds: a 150 mm wheel – rpm between 1700 and 3000 rpm. A 200 mm wheel between 1400 and 2100 rpm and a 250 mm wheel between up to 1450 rpm. In general, you can say that a CBN wheel performs better if the speed is higher up to the above-mentioned limit. The 250 mm wheels though work brilliant on the slow speed grinders like the Tormek T7 and T8. It works very well but there is 1 little annoying thingy. When sharpening, the tip of your chisel always gets a bit magnetic. Normally the speed of the wheel will throw the fine metal part away. Here, however, the speed of the wheel is so low that if your chisel is cut, you have to pull the magnetic particles off the edge with a swab. A magnet under the wheel will also do…
CBN wheels can be obtained in 150 mm, 200 mm and 250 mm. The width is 40 mm. The hole is always 12, 12,7, 15, 16, 20 or 32 mm. There is also a tool that allows you to mount the wheel on the axle of your lathe. Then you can choose your own speed to sharpen! Putting a CBN into use for the first time it can be very aggressive. If you have sharpened a few chisels, this will be less. Don’t be afraid! It is not that the wheel wears very quickly. After the first few chisels, it keeps its sharpness very long.
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.
The CBN sprinkling is also applied to a hone steel. This is of course the finest grain. They are in the form of a marker and in a flat plane. There is also one with a flat surface and a marker shape. The flat surface I use for the chisel (skew) The both bended sides for my large and small scales guts respectively. Well… That has become a long story and for many people maybe a bit boring, but I hope someone has something to it.