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Shaping Advice at Water Cooled Grinding
On a grinding wheel with low RPM, you need to press harder than on a high‑speed grinder
to remove steel. The same high grinding pressure on a high‑speed grinder will cause over‑
heating. Do not be afraid of pressing hard on the tool. Press with your fingers close to the
cutting edge. This does not apply if you are using a Diamond Grinding Wheel. Always apply
a low pressure when sharpening on a Diamond Grinding Wheel.
Move the tool side to side and use the whole width of the grinding wheel to avoid groov‑
ing. Reduce pressure or lift the tool when moving to a new spot on the grinding wheel.
When shaping large surfaces such as a skew chisel with a straight edge, too little grinding
pressure slows down the grinding. If you are using the Original Grindstone or the Blackstone
Silicon you can re‑activate the grindstone several times during sharpening with the SP‑650
Stone Grader to speed up the work. If you are using a Diamond Wheel Coarse you will al‑
ways have a fast steel removal without having to re‑activate the stone.
Some Comments on Dry Grinding
Not all grinding wheels are suitable for the precision sharpening of edge tools. Standard
bench grinder wheels are often too hard and become glazed easily, which reduces the rate
of steel removal and causes overheating of the tool. Use an aluminium oxide wheel with the
correct binding – not too hard to avoid glazing and not too soft to reduce grooving.
The surface of the grinding wheel must be kept fresh and clean. Worn grains must wear
away so that new ones come into play. If not, the surface becomes glazed and the grains
will rub instead of cut. This will increase friction and heat development. Use a diamond hand
wheel dresser to maintain the shape and condition of the surface. Do not attempt to use the
Tormek TT‑50 Truing Tool for this task.
HSS steel can withstand a much higher temperature than carbon steel without decreasing
the hardness. However, at the tip of the edge, which is very thin, the temperature can easily
rise to a level that will affect the hardness. Therefore, grind cautiously at the tip of the edge
and do not allow it to become blue. Overheating HSS steel can cause a decrease in the
hardness by as much as 4 HRC, which shortens the life of the edge. If you cool it in water,
do not cool abruptly from a high temperature as this can cause micro cracks invisible to
the naked eye.
A bench grinder must be handled with knowledge and care. These instructions show how
to use the Tormek jig system on a Tormek machine. If you use a bench grinder follow the
instructions enclosed with the BGM‑100 Bench Grinding Mounting Set and the safety in‑
structions that come with your machine.
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