Carving wood with blunt tools can be compared to slicing a loaf of bread with a spoon. The key to all good carving and the proficiency of any carver is dependent on the sharpness of the chisels. The cutting edges should do the work – in a sense, you are merely there to support and guide them.
You will need to be able to identify the faults in a cutting edge. The illustration below shows a blade with a number of serious defects.
There are many products on the market which are effective in producing a razor finish. However, a basic knowledge of sharpening is essential for all. The information in this section identifies the series of stages which should be used as appropriate.
- The ground angle of the cutting edge is too great. The ideal angle of a carving tool varies between 20 and 30 degrees. The flexibility of 10 degrees is subject to the hardness of the timber to be carved. Obviously the smaller the angle, the weaker the edge becomes. A general guideline is that the length of the bevel should be around twice the thickness of the chisel’s blade.
- It is generally desirable for the cutting edge to form a 90 degree angle to the chisel’s shank with the exception of a skew chisel.
- The blade has been chipped possibly by carving a piece of grit embedded in the timber, or it may mean that the chisel’s edge angle is too small for the density of the timber. In the worst scenario the metal may have become brittle, so if the blade continues to chip, it will need re-tempering. A perfectly clean straight cutting edge should be maintained.
- The outside tips of the cutting edge have become rounded over. They should be square and intact, forming pointed corners.