Clean Cuts

Sharpening tips for your woodworking tools

Like Diamond stones, they're also ideal for sharpening carbide tools and are available in a wide range of sizes and shapes. So, which stone is really best? Which should you own? The answer to this question is simple...each type of stone does what it's supposed to do best. Silicon-Carbide and Waterstones cut fast and are best for removing deep nicks and gouges from steel tool edges. Coarse India stones can also accomplish this task and a Fine India stone can also hone an edge quite nicely. A Soft Arkansas stone cuts about the same as a Fine India stone. Hard Arkansas stones are a great choice for honing razor-sharp edges.

It's important to note that oil is used on “Oil Stones”, NOT to reduce friction, but to suspend and carry away the “swarf” (a nice little Norwegian word that means “little flakes of metal”). Light machine oil, sewing machine oil, honing oil (which is mostly mineral oil) or kerosene (alone or mixed with any of the above) all work quite well. Don't use vegetable oil, as it will clog the stones very quickly.

The sharpening process
For a chisel, plane iron or other bevel-edged cutting tool, start by flattening the back side of the tool on a fairly coarse stone. Be sure to push the tool over all of the stone to be sure the stone wears evenly. Turn the edge over, bevel side down and rock it forward till the oil (or water) squishes out from the front lip of the blade - this is typically the correct bevel angle. Using a stiff wrist, move the edge over the full stone's surface to ensure even wear.

The ideal bevel angle for chisels and plane irons is about 30-degrees. Hone an edge too thin and although it becomes very sharp, it also becomes brittle and breaks prematurely during use. Make the bevel angle too steep and you'll get a wedge that will be sharp, but difficult to work with. It's usually best to maintain the bevel that comes on the tool when you buy it...providing that angle works well for you. A rule of thumb - the length of the bevel should be about twice the thickness of the blade. Special Bevel Gauges are available for checking the accuracy of your sharpened bevel angles.

Check the squareness of the blade frequently as you sharpen it - it's easy to apply sharpening pressure unevenly and end up with a blade that's not square to the handle (in the case of a chisel). If you must, use a try square or combination square to check this squareness.

Once the edge is properly honed, turn the tool back over to the flat side and with a few light strokes, remove the small burr on the back side. Failure to do this means this film if thin steel will simply flop over and cover up the sharp edge. Stroking too many times on the flat side will also ruin the cutting edge.

Here are some simple tips:

• All stones (except diamond & ceramic stones) get dips and bumps in their surfaces. Using them evenly helps to delay this problem...but not forever. It's a good idea to periodically re-flatten your stones by rubbing them in a circular motion over a piece of 1/4" plate glass or Formica countertop covered with a slurry of loose grit such as carborundum powder.
• Adjustable Honing Guides can make easy work of maintaining bevel angles when sharpening chisels and plane irons.
• If you're looking for a nice strop to finish-up a razor-sharp edge on your tools, a leather shop or shoe repair service will sell you a good, thick piece of leather for this purpose. To perform this stropping operation, pull the bevel across the smooth side of the leather...unlike the pushing action used with a benchstone.
• If your silicon-carbide stone becomes clogged with swarf, it will no longer cut steel. Rescue it with an overnight bath in kerosene, followed by a brisk rubbing with a stiff brush.
• You can always tell a dedicated woodworker by how little hair they have on the backs of their forearms and hands. That's the favorite place for testing the edges of tools. If it shaves hair, it's sharp!

The methods used by woodworkers for sharpening their tools is a personal statement, as unique as the way they sign their names. Every one of them has strong feelings about the best way. Ask them about their opinions of these best ways and you'll learn a lot.

PART TWO - Sharpening Lathe Chisels