INCRA Ultra Lite - Manual (Page 7)

Tail Cuts
To cut the tails for a half blind dovetail, begin by
cutting a dovetail shaped rabbet on both ends of the
two boards, see Figs. 33 and 33a. The rabbet needs to
be
7 ⁄
32 " wide. Do not cut the rabbet width in one pass.
Instead, use three or four light side by side passes to
sneak up on the rabbet width. You can use the
1 ⁄
32 " scale
in your Ultra Lite as a reference so you’ll know how much
you have widened the rabbet with each pass.
Now clamp the two tail boards to your Right Angle
Fixture as shown in Fig. 34, and make the tail series
of cuts that you determined in Step 4. As always, using
good router technique, sneak up to the first tail cut in
several light side-by-side passes to avoid splintering the
edge of the stock (see Tip on page 10). After completing
the cuts, flip the boards end for end and repeat the cuts.
Pin Cuts
Set your Incra Jig to the first pin cut on the template
that places the bit in front of the fence. Slide the
stop positioner onto the fence and locate the stop as
close to the dovetail bit as possible (without actually
touching the bit) and clamp in place. See Fig. 35. The
stop positioner will be used to limit the length of the pin
cuts.
Place one of the pin boards face down on the router table
as shown in Fig. 36 and make the pin series of cuts
determined in Step 4. Be sure to use a good rubber
soled push block as shown. Make the cuts on only one
end of the board for now. After making the cuts, check
the fit between this board and one of the tail boards. If
the tails won’t fit all the way into the pin sockets, simply
lengthen the pin cuts by moving the stop positioner away
from the router bit. (See Tip below.) Recut the pin board
and again check the fit. Once you have a flush fit, make
the pin cuts on the opposite end of the board and on both
ends of the remaining piece.
5
6
7
FIG. 37
Move stop
back this far
to achieve a
flush fit
FIG. 33
Cut the rabbets Dovetail shaped rabbet
cuts on both ends of
the tail boards
Rubber soled
push block
FIG. 33a
Rabbet width
7 ⁄ 32 "
rabbet
After making your first series of cuts, check the fit
with one of the tail boards. If the tail board won’t fit
all the way into the pin board, just measure the
distance it protrudes. See Fig. 37. This is the distance
you need to move the stop away from the bit to achieve a
flush fit.
Pin board
Tail board
FIG. 34
Cut the tails
Wooden
handscrew
clamp
FIG. 35
Set stop positioner
Position stop on
outfeed side of
bit as close as
possible to the
cutter
FIG. 36
Cut the pins
Rubber soled
push block
Clamp two boards
with rabbets facing
out as shown
Stop
positioner
Fence
12 13
After making a half blind dovetail, you may notice that the
joint looks symmetrical, but the edges of the two boards do
not align flush, see Fig. 38. This simply means that when
you centered the board using the method described in
your owner’s manual or
Incra Master Reference Guide and
Template Library , you were close but not quite perfect. Of
course practice makes perfect, but there is another method
for cutting the tail boards that will ensure a flush alignment
regardless of how well your board was centered. Just
make sure when you clamp the tail boards to the Right
Angle Fixture that the dovetail shaped rabbets on
all the
boards face the cutter, see Fig. 39. That’s all it takes!
Remember that even if you use this procedure, you should
still center first to ensure a symmetrical looking joint.
FIG. 38
Boards
not
aligned
flush
Dovetail shaped
rabbet cuts
face the cutter
Not
flush
FIG. 39
VARIATIONS
The drawings at right show a standard equally spaced
dovetail joint (Fig. 40) and several variably spaced dovetail
joints (Fig. 41). Although these joint patterns look quite
different from one another, they all have one thing in
common. They are all made using the same equally
spaced dovetail template. By learning the variations
technique described below, you can customize the joint
pattern produced by any template. This technique works not
only for half blind dovetails as pictured, but also for box
joints, through dovetails, and with a little study, you can
even customize the decorative Double and Double-Double
joints. In general, pattern variations can be designed by
observing a few simple rules.
Select cuts to be left out
Align the center of your board with the center cut you
plan to use on the diagram. Then choose the cuts you
want to leave off on one
* side of the diagram. Determine
which side of the diagram will be the pin cuts and which will
be the tails (see Step 4 on page 11). Leaving cuts off of
the tail side of the diagram creates wider tails. (See
Example 1 on Fig. 41.) Leaving cuts off of the pin side of
the diagram creates wider pins.
*
Although a bit more complicated, cuts can be left off of both
sides of the diagram, resulting in a pattern variation that has
both wider pins and wider tails. (see Example 3, Fig. 41)
Always modify the pattern
symmetrically
For example: if you decide to leave out the first two “A” cuts
on your stock’s width, you must also leave off the last two
“A” cuts.
Cut the joint
Any cuts left out on one side of a pattern will be used
to modify the other side. If you decide, for example, to
leave off cuts 2A and 7A when you are cutting the “A” cut
boards, just make cuts 2A and 7A along with all of the “B”
cuts to automatically modify the “B” cut boards.
BEGINNER’S TIP
2
3
FIG. 40 FIG. 41
Equally spaced
dovetail
Tails Pins
EXAMPLE 1
Tails Pins
EXAMPLE 2
Tails Pins
EXAMPLE 3
FIG. 42
Designing
the pattern
variation
FIRST: Align center of board with “center cut” on diagram
SECOND: Determine which cuts will be pins and which will be tails.
(Step 4, page 11)
THIRD: Decide if you want the pins or the tails to be wider.
Example: Leaving out the “A” cuts will create wider tails; Leaving
out the “B” cuts will create wider pins.
FOURTH: Write down or circle the cuts you wish to leave out.
Center of
board
aligned
with
“center
cut”
Dovetail bit
1