Sharpening Tools

Some thoughts about the sharpening and the use of tools

1. Protect your edges from being damaged. You have worked hard to achieve a fine edge on your tools. Don't lay them down where they will contact other tools and get damaged.
2. Protect yourself from your tools. If you lay down a tool, do so with the edge away from you.  When storing or transporting tools keep the edges from coming in contact with flesh. The edges are sharp!
3. A good rule is to only have one tool out at a time that you are working with.
4. To sharpen a new tool or one that has been abused, progress from shaping (coarse abrasives) to sharpening (medium, fine) to honing (very fine, strop), maintaining the same angle through out. Tools which had been sharpened in the past may need only a touch up.  The point you have to go back to (coarse, medium, fine, very fine abrasive) depends on the condition of the tool.
5. The bevel on the tool is most critical.  The thinner a bevel, the sharper it is but also at the same time a thin bevel is more fragile.  
6. A "feather edge" or a "wire edge" is created when it is time to switch from a coarser abrasive to a finer one.  This means the whole edge or that part you want sharp.
7. Examine the tool from time to time to see how you are doing.  Listen to your tool.  It can tell you a lot.
8. When sharpening a tool, think of using a rake in a sand box.  Coarse abrasives put grooves into the steel, finer abrasives produce less scratching.  Two surfaces coming together to form an edge that have grooves in them cannot produce a fine edge. 
9. A "feather edge" may feel sharp but contact with wood will break off the edge and you will have an instantly dull tool. The "feather edge" must be honed off.
10. Honing results in bevels that are real shiny. This means that the surface variations in the steel approach the wavelength of light.
11. Do not test the edge by running your finger on the edge.  Not only is it dangerous but it is a poor way of testing the edge. Test the edge by cutting a thin slice off the end grain of a soft wood like white pine or basswood.  The resulting cut should be smooth and polished.
12. Hard steel will take and keep an edge longer than milder steel.  A properly sharpened tool will stay sharp for a long time.  A little stropping from time to time will maintain the edge.  However, too much stropping will cause the edge to round over and become less sharp.

If buying tools look for Rockwell hardness HRC 59 to HRC 62. The hardness of a material is measured by a machine invented by Hugh (and Stanley) Rockwell and uses the principal of differential depth measurements.

Recommendations for different bevels:

• 15 to 20 degrees - Knife  
• 15 to 20 degrees - Gouges, v-tools to be used by pushing
• 20 to 25 degrees - Gouges used with a mallett

For tools with two bevels like a knife or a straight chisel, the bevel on each side is half of the total bevel.