Keeping
tools sharp saves time and energy. When
you�re in a hurry to get your pruning work done, you may not want to take the
extra few minutes needed to stop and sharpen your tools. But it�s well worth
the effort for two reasons: 1)
Your work will go faster and easier with sharpened tools. 2)
The clean cuts you get with sharpened tools are healthier for your plants and
trees. Immediately
after being cut, a plant oozes sap or resin, which dries to create a protective
shield. But that�s just the beginning of the healing process. The plant also
diverts energy from its growth to the damaged area while the wound is healing.
Obviously, then, you want to help ensure that the tree will heal as quickly
as possible. One way to do this is to make sure you create a smooth surface
by a clean cut using a sharpened tool. Not only will the plant heal more quickly,
and thus begin growing sooner, but it will be exposed to less damage from diseases,
insects, fungi and weather extremes. Following
these steps will help you learn the proper way, then, to sharpen your pruning
tools. Step
1: Clean the blades Whatever
type of pruning tool you are using, clean the blade with a stiff brush and
soapy water to remove any rust, clumped dirt or other debris. Dip the pruners
in a solvent, such as kerosene, to clean off any sap. If you�ve used your tools
on evergreens, be sure to clean off the pitch residue using either oil or kerosene,
too. After drying them, wipe the blades with a light coat of motor oil. Step
2: Examine the sharpness Examine
the blade edge to determine the correct sharpening angle (usually about 10
to 15 degrees) (see Photo 1, at left). It�s also a good idea to check the manufacturer�s
guidelines for more specific sharpening instructions and cautions. Remember,
for an anvil-type pruner, you�ll sharpen only one blade but you must sharpen
that blade on both sides. The
choice of sharpening tools is largely a matter of preference: *
Whetstones, the most common choice, offer many gradations and sizes, though
you may find that a longer one is easier to work with. *
A diamond-coated flat file requires only water for lubrication, remains flat
for fast sharpening and is durable enough to last a lifetime. *
A sharpening steel is useful for finishing or for a quick fix. *
Grinding stones require extra caution because they transfer friction heat that
can affect the metal temper, making it more brittle. Because
the use of whetstones is the most common of these four types, we�ll describe
that technique in detail here. Step
3: Begin grinding the blades Start
with a medium-grain whetstone (see Photo 2, opposite page, top). Thoroughly
wet the stone by soaking it in water or a lightweight motor oil. (For an even
lighter finish, some people prefer using a vegetable oil.) Because water quickly
evaporates, oil is usually a better choice. It will not only act as a lubricant
but carry away grit during the sharpening process. To
maintain the correct angle, press the blade against the concave side of the
stone while sharpening. Use numerous smooth strokes, moving the blade in one
direction toward the tip�as if you are trying to shave off a thin slice from
the whetstone. Don�t press too hard. For
every 10 strokes to the outer bevel, apply one stroke to the inner angle. Keep
the stone wet by periodically applying more water or oil. (Don�t switch between
the two, however. If you start with oil, continue using oil.) If
the blade has a nick, use a file to remove the bent metal piece. If it has
multiple nicks, you may need to start the sharpening process with a coarser
stone. Step
4: Smooth the edges Once
you�ve achieved the proper angle and sharpness, move to using a finer-grain
whetstone and continue sharpening until you achieve a razor-sharp edge. Don�t
reduce the beveled edge to less than 1-mm thickness. A finer edge will not
increase sharpening ability but will make the blade more fragile and prone
to damage or breakage. Step
5: Test the sharpness You
can conduct a preliminary test without having to make a trip outside. Simply
hold the cutting edge up to a light source. If you can see light reflecting
off the blade edge, it�s not yet adequately sharpened. Once
the tool passes the light-reflection test, you�re ready for the ultimate test
of trying it on the size of branch it is designed to cut (see Photo 3, at middle
right). If you�ve sharpened the blades properly, they will make clean, easy
cuts. If the blades pull or catch, they�re not sharp enough. In that case,
continue sharpening with the fine whetstone or switch to an extra-fine stone.
Retest as necessary, again being careful not to over-sharpen the blades. Step
6: Add a coat of oil Finish
off the blades by rubbing a light coat of oil them (see Photo 4, bottom right).
Remember: dirt that sticks to your tools acts as a sponge, collecting moisture
and causing rust. So be sure to keep dirt off your tools when they�re not in
use. When
sharpening other types of tools, you may need to make some modification of
these steps. For example, when sharpening anvil-type pruners or clippers, sharpen
only one blade but on both sides. Avoid putting a curve on the blade�s edge.
Unless the edge is perfectly straight, it won�t strike true against the flat
anvil, and strands of plant tissue will cling to the blade after each cut. Before
sharpening shears, you might find it easier to take them apart. Keep in mind
that regrinding blades usually is not recommended. Doing so tends to change
the cutting angle and destroy the fluting. Plus, regrinding can create a convex
cutting edge that leads to poor shearing action and difficulty in cutting. For
scissor-action "bypass" lopping shears, sharpen only the outside surface of
each blade. This will maintain the cutting surface so the blades will cut cleanly
as they slide past each other. Remember that the inside blade surfaces need
to remain flat, so you should clean them but not sharpen them. When
you�re sharpening your tools, it�s also a good idea to check the tension screw
between the blades. If needed, adjust the screw to allow more freedom of movement
while still ensuring that the blades are close enough together to work properly. What
if you have a saw that needs sharpening? That�s a tedious job that takes special
skills and special equipment, so you�ll most likely want to leave it to a professional.
Check the Yellow Pages under "Sharpening services" or try a local hardware
store. After
you�ve sharpened a tool several times, you may notice that the cutting angle
is becoming rounded (an edge that is more than a 90-degree angle). At this
point, the blades start working with a crushing action instead of a clipping
action. This indicates the blade is worn out, and it�s time to replace it or
the entire tool. Protect
your investment in quality tools and limit the need for sharpening by performing
routine maintenance between uses. Find a handy, easy-to-reach spot to hang
up a rag that�s dry on one end and has oil on the other. Use it to wipe off
your tools, keeping them clean and oiled after you�re done using them. It�s
especially important to do this small task before putting away your tools for
the season. Another
handy trick is to keep a 5-gallon bucket filled with coarse builder�s sand
in your garage or tool shed. Dip the metal blades of each tool into the sand
and pull them up and down several times. This will remove any mud or clinging
soil. Next, use a wire brush or steel wool to take off any rust or other particles
of debris that remain. You also can pour some motor oil into the bucket of
sand so that, when dipping them in the sand to clean them, you give them a
coating of oil. Despite
these recommendations, if you still don�t lubricate your tools regularly, at
least do so at the end of the season, applying a light coat of oil to the blades.
Also protect wooden-handled tools with linseed oil or a coat of varnish. And
lubricate any moving parts. Then store tools in a dry place. By following these
steps, your tools will be ready whenever you are, any time of the year.
|