Table Saw Special Operations
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Pg. 1-2, Pg
3-4, Pg 5-7
in a home workshop or a commercial establishment, most woodworkers
often find it necessary to bend wood to a particular shape.
It may be needed on a furniture project-the apron on a drum
table or round stool-or on other projects like a garden arbor
with an arched top or a doorway with a semi-circular upper
structure. Commercial establishments, of course, can bend
wood to almost any shape by steaming it or using chemicals
to make it flexible. In the home workshop, you don't usually
have the special bending equipment, but you can still do an
impressive amount of wood bending just by working on the table
saw and using either the kerfing technique or a thinning out
process. You must use straight grain lumber for any bending.
4-1. A good amount of wood bending can be done mby
using the kerfing technique. Kerfs can extend the full
length of the workpiece or be confined to an area.
popular method of bending wood without steaming is by kerfing
What this method accomplishes is a reduction in stock thickness,
while allowing room (between the cuts) so the wood can bend
back on itself. The depth of the kerfs and their spacing are
the important factors and are variable. Deep kerfs, closely
spaced, allow the sharpest bends (Figure
4-2. The kerf spacing can be veried, depending on
the sharpness of the bend. (A) The kerfs should be more
closely spaced in the sharpest bend area. (B) Greater
specing is sufficient wher bend begins to straighten.
wood with minimum loss of strength, proper kerf depth and
spacing should be determined using a simple test.
a sample kert in a test piece of stock that you wish to bend
In 3/4" stock try a kerf that is 5/8" to 11/16" deep. Position
the test piece, kerf side up, on a flat surface and hold it
in place with a clamp on the right side of the kerf. The distance
from the kerf to the edge of the surface on which you have
placed the work should equal the radius of the bend you need.
Lift the stock at its free end until the kerf closes and then
measure the amount of lift at the edge of the table. This
tells you the distance required between kerfs.
4-3.Make this test to determine, at least as a start,
the kerf depth and the spacing you need to make a particular
bend. Click on image for larger view.
4-4. Use a miter guage extension to mke the kerf
spacing guide. The distance from the pin (8d nail) to
the slot automatically spaces the kerfs.
work like this calls for a considerable number of kerfs correctly
spaced, you should work with a kerf spacing guide like the
one shown in Figure
4-4. After you have secured the guide to the miter gauge,
cut a saw slot through it and then drill a hole for a nail
to serve as the guide pin, spacing it away from the slot a
distance equal to the required kerf spacing. Make the first
kerf with the workpiece butted against the guide pin. The
distance between the remaining cuts is automatically gauged
by placing the last kert over the guide pin (Figure
4-5). When the kerfs must be cut in a central area of
the stock, make the first cut without using the guide.
4-5. By placing the last kerf over the guide pin,
the work is accurately positioned for the next cut.
the number of cuts, first find the circumference of the circle
that will form the corner of the project. Divide this number
by the total number of corners on the project. This will be
the length of one corner. Divide the length of the corner
by the total width of the saw kert plus the spacing between
the kerfs. This will give you the number of cuts you'll need
to make. The formula for this is:
Circumference ÷ Number of Corners = Corner Length
Corner Length ÷ (Kerf Width + Kerf Spacing) = Number of Cuts
Example: Calculating the number of cuts for a 12" dia. circle,
used on a four corner project, with a saw kert of 1/8", and
kerf spacing of 3/4".
= 3.14 x 12" = 37.68"
37.68" ÷ 4 = 9.42"
9.42" ÷ (1/8" + 3/4") = 9.42" ÷ 7/8"(.875) = 10.77 or 11 cuts
is complete, bend the wood slowly until the curve you need
is achieved. Wetting the wood with hot water (even if you
must soak it awhile) will help the bending process. Also,
use a tie strip, tack-nailed in place, to hold the part's
shape until it is permanently attached on an assembly.
form irregular curves if you do the kerfing on both sides
of the stock and/or vary the kerf spacing. When the kerfing
is exposed, veneers may be glued in place to conceal the cuts.
If you're working on an outdoor project, coat the kerts with
waterproof glue before making the bend. Wood dough or putty
can be used to fill the crevices. When the work has been correctly
sanded and finished, it will require a close examination to
reveal the method used to make the bend.
4-6. Wood can easily be bent when you reduce its
thickness in the bend area. This is the "thinning
out, the stock's thickness is reduced the full length of the
bend area (Figure
4-6). In effect, you are producing a length of veneer
which is an integral part of the wood. The thinning out can
be done with the dado or molder head. It can also be done
by resawing the stock on the bandsaw. This method permits
very sharp bends; but, since the veneer area won't have much
rigidity or strength, corner blocks should be used to provide
structural strength (Figure
4-7). Thinned out sections that have the wood grain running
lengthwise will be stronger than those where the grain runs
4-7. Thinned out areas, even kerfed areas, cna be
reinforced by using corner blocks. Click on image for
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