Keeping the Edge
(or Why Do You Look So Dull?)
by
Sherwood Heggen
So many would be excellent wood-workers have one common fault
limiting their success. They don’t keep their tools sharp. This is
much the same as a person who thinks they take good care of their
car and neglect maintenance of the constant wear items such as
brakes, shocks, and exhaust system. Have you taken a good look at
the cutting edges of your plane blades and chisels lately? In this
Gadgets and Kinks, putting a sharp edge on those tools will be the
subject.
To many,
holding the tool to the spinning surface of a grinding wheel is
sufficient to get a sharper edge. Actually, that would only be
sufficient for damaging the tool. That method can cause overheating
of the edge causing it to loose its temper, will cause an uneven
edge and bevel to the tool, and will only shorten the life of a tool
that could otherwise be made useful for years to come.
There are
many fine articles printed and sources of information on
sharpening tools available for those who seek them out. This article
will serve to get the wood-worker interested in a making sharp tool
edge with a minimum of equipment and expense. From there, the sky is
the limit for investing in equipment for methods to produce the
keenest edge possible.
How do you
know when a tool needs sharpening? Understand that the face of the
tool must have a perfect constant bevel and the back of the tool
must be perfectly flat to create a razor sharp edge. Take a close
look at the front and back edge the blade of a plane, for instance,
to see if the edge as a rounded appearance or if it is nicked. Does
the tool allow almost effortless work. If not, it is time to read on
and then go put a sharp edge on it.
Some
very basic tools are required to put a sharp edge back on a cutting
tool that will be satisfactory for the common woodworker/boat
restorer. They are a holding jig to maintain a constant bevel angle
on the tool being sharpened, a flat surface such as a piece of glass
or a cast iron saw table, and wet/dry sandpaper. (Refer to picture
#1.)
The
holding jig is available at stores that cater to woodworkers. It is
a necessary piece of equipment for holding the tool blade at a
constant angle to produce correct results. Place the chisel or blade
in the jig making sure that is secured squarely in place. Now adjust
the angle of the blade so that the face of the bevel on the tool
makes full contact with the flat surface. This will preserve the
original bevel designed for the tool. Lay a piece of 320 grit
wet/dry sandpaper on the flat surface. Proceed to draw the tool
across the sandpaper with the edge in trail. Check the progress of
the action after a number of passes. The surface of the bevel should
have a consistent appearance to its surface as in the picture below.
If not, continue to draw the tool across the sandpaper until a
consistent surface exists. Then switch to 400 grit paper and
continue to draw the tool to produce an even finer edge.
Once
satisfied with the effort, it is time to remove the tool from the
holding jig to clean up the back side of the tool. A very slight
burr will exist from working the bevel side against the sandpaper.
Lay the tool’s back side on the 400 grit sandpaper and work it in
small circles to clean off the burr. Now, be careful how you handle
the tool. It is sharp!
Alignment
of the blade in the plane comes next to provide for a square cut.
Place the plane on a piece of paper (to protect the blades edge) on
a hard, flat surface and place the blade in its holder. The blade
edge should rest squarely on the flat surface. Clamp the blade in
place according to the devices of the plane. Adjust the depth of the
blade for the slightest possible cut and do a trial run on the edge
of a piece of wood. Now, can you say, “Wow, that is really
something”? You should be able to remove wood shavings thin enough
to see through.
This
method is very simple, but effective. For the purist, oil stones of
different grades, water cooled grinding stones, strops, etc, would
be the essential equipment to create the
microscopically perfect edge with which one could do microsurgery.
It would be nice to have such a privileged edge on a tool, but
isn’t necessary to produce excellent results with our chisels and
planes to get through the restoration project at hand.
Keeping a
sharp edge takes some understanding of the process of planing. Most
woodworkers make the mistake of drawing the plane back with the
blade resting on the planed
surface after each cutting pass. As it is drawn back, the backside
of the blade is being honed by the abrasive qualities of the wood
and the perfect flat edge becomes rounded off. To make the plane
sharp again, material must be removed past the rounded portion to
bring the edge back. Also, be sure the material you are planing or
chiseling has no screws or nails in the path of the cutting edge of
the tool that will nick the edge. Pretty basic, but so often
overlooked.
Go out
into the shop and see what is dull and give this a try. I assure you
once you properly sharpen one tool and find out what a difference a
real sharp edge makes, you will be
sharpening every tool you have. Here again the phrase of “don’t
destroy it; restore it” rings true. Many cutting tools are set
aside because the edge is gone. Well, now you know how to take care
of that. Enjoy! |