Biscuit
Joining
Right
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Most woodworking
projects re-quire at least some assembly. This is especially true
for projects such as tables, cabinets or bookcases where wide panels
must first be built up from several narrow boards.
Traditionally,
woodworkers have used dowels for these assemblies. As you might
expect, dowels add strength to certain types of joints, but they
serve an equally impor-tant function by keeping the pieces properly
aligned during assembly and gluing. The major drawback with doweling,
however, is that each hole must be perfectly positioned or the individual
pieces simply won't go together. Even a slight error can cause a
lot of pounding and frustration.
During the
1950's a new assembly system called biscuit joinery was developed
in Europe. This system uses flat wooden wafers or biscuits which
are glued into semi-elliptical slots on each side of the joint.
Due to the shape of the biscuits, the exact location of the slot
is much less critical than a dowel hole. Minor adjustments can even
be made during assembly, so projects go together much more quickly
and yet there is no sacrifice in strength or overall performance.
That's why biscuit joinery is rapidly becoming the preferred assembly
system for professional furniture and cabinet makers worldwide.
In addition
to its advantages for panel assembly, biscuit joinery can often
be used to replace more complicated and time consuming techniques
including spline, tongue-and-groove, mortise-and-tenon and dado
joints.
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Biscuit
Joiner Setup and Features
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Figure23-1.
The biscuit joiner is powered by the Mark V's powerplant and
can be used with either the Model 500 or Model 510.
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The biscuit
joiner housing attaches to the quill and the blade arbor attaches
to the main power spindle of the Mark V's powerplant (Figure
23-1). It may be used with either the Mark V Model 500 or Model
510. Follow the setup instructions in the Owners Manual that came
with your biscuit joiner.
Some of the
important features (Figure
23-2) and capacities of your biscuit joiner are:
- Spring-loaded
workpiece guide and safety guard help improve operator confidence
and safety.
- Engraved
centerline on guide permits easy alignment of workpiece.
- Adjustable
depth stops and guide rod grooves permit easy use of three different
biscuit sizes (#0, #10 and #20) for a variety of applications.
- Adjustable
pins in guide penetrate stock to provide more positive control
and reduce kick-backs.
- Carbide-tipped
blade will provide years of normal service without sharpening.
- Built-in
dust chute for easy at-tachment of standard 2-1/2" dust collection
hoses.
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Figure23-2.
Familarize yourself with these important features of the Shopsmith
biscuit joiner.
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Biscuit
Sizes and Construction
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Figure23-3.
The three available biscuits are shown here.
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Shopsmith biscuits
are produced from select grades of beech. For maximum strength,
the grain is oriented at a 45° angle to the long axis of the biscuit.
During production, biscuits are exposed to many tons of pressure
which compresses the fibers and produces a waffle-like surface for
better glue absorption and adhesion.
When glue is
applied to the biscuits, the moisture in the glue causes the biscuits
to expand by about 15% of their original thickness and the joint
becomes tight. Since this expansion occurs very quickly, glue should
never be applied to the biscuits until you are ready for final assembly.
Biscuits should also be protected against water or extremely high
humidity. A coffee can with a tight fitting lid makes a good storage
container.
Biscuits are
available in three different sizes to meet a variety of applications
(Figure 23-3).
All biscuits are 5/32" thick.
#0 biscuits
are 1-3/4" x 5/8". They are best for joining smaller workpieces
and for edge-to-edge assemblies where high stress is not anticipated.
They are also useful for joining narrow pieces such as cabinet frames
end-to-edge.
#l0 biscuits
are 2-1/8" x 3/4". They are recommended for general purpose joinery
on all types of projects.
#20 biscuits
are 2-3/8" x 1". They are recommended for use on larger projects
or joints--such as a table skirt and leg--which will be subject
to high stress or twisting forces. They also provide greater penetration
and a larger gluing surface, so they are well suited for plywood
or particle board applications.
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Biscuit
Joiner Safety
Read, understand
and follow all safety and operating instructions in the Owners Manuals
that came with the Biscuit Joiner and with the MARK V on which it
is mounted.
- Wear safety
goggles, safety glasses with side shields or a full face shield.
- Tuck long
hair under a hat or tie it up. Do not wear ties, gloves, jewelry
or loose cloth-ing. Roll sleeves up above your elbows. Wear non-slip
footwear.
- Before
mounting the biscuit joiner on the Shopsmith MARK V, turn on the
MARK V and set the speed dial to SLOW. Then turn off and unplug
the machine before proceeding.
- When mounting
the biscuit joiner on the MARK V, be certain all locking screws
are tightened securely before turning on the machine.
- Be sure
the blade is mounted in the biscuit joiner with the teeth pointing
in the direction of the arrows on top the housing. Installing
the blade backwards will result in kick-backs and injury.
- Connect
a dust collection system to the biscuit joiner dust chute or wear
a dust mask.
- Do not
allow anyone to stand directly in front of the opening of the
dust chute.
- Move the
workpiece slowly into the blade--never force it. Feeding stock
too rapidly could cause kickbacks.
- Do not
stand directly in-line with the workpiece being fed. In the event
of a kickback, you will be hit.
- Do not
rest fingers in the miter gauge slots where they could be trapped
and pinched by kicked back stock.
- Always
use the push block in your right hand to feed stock into the blade.
This is especially important when working with small stock.
- Use your
miter gauge and/or rip fence as a stop when working with stock
less than 6" long or wide.
- Always
be certain the pins protrude from the guide before beginning operations.
Failure to do this could result in the workpiece being grabbed
and thrown by the rotating blade.
- Listen
for chatter and signs of looseness at start-up. If you hear, see
or suspect problems, turn off the power and unplug the machine
immediately. Correct any problems before proceeding.
- Never
use the biscuit joiner for jobs it is not intended to perform
such as sawing, grooving, etc.
- Never
exceed speed setting T on the MARK V's speed dial
for biscuit joiner operations.
- Never
attempt to use the biscuit joiner on stock less than 3/8" thick.
- Never
operate the biscuit joiner without the housing and guard in position.
- Always
keep the blade clean and sharp.
- Use only
Shopsmith blades and parts for your biscuit joiner. Using non-Shopsmith
blades or parts will create a hazardous condition and will void
your warranty.
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Basic
Biscuit Joinery Techniques
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Figure
23-4.
Mark centerlines on both pieces of stock to assure proper
alignment.
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Marking Joints-
The only marking normally required for biscuit joinery is to indicate
the centerline for each biscuit's location. These markings are usually
made on the back side of the stock and may be made with a square
(Figure 23-4) or
freehand. Marked centerlines are then aligned with the engraved
centerline on the biscuit joiner guide while quill and worktable
adjustments are then used to control the biscuit's vertical position.
Figure 23-5 shows
typical markings for various types of joints.
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Figure
23-5.
Here you see typical centerline markings for various types
of joints.
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Basic Adjustments
and Cuts- After mounting the biscuit joiner on the Mark V (Figure
23-6) and establishing a basic setup as shown in the biscuit
joiner Owners Manual, several adjustments must be made before using
the accessory. These basic procedures apply to all types of joints,
so review these steps before each biscuit joiner operation.
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Figure
23-6.
Attach the biscuit joiner to the quill and tighten the housing
collar capscrew. Don't forget to tighten the setscrew which
holds the blade arbor to the spindle.
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Begin by selecting
the size biscuit you will be using and set the depth-of-cut accordingly.
This is done by unplugging the Mark V and compressing the spring-loaded
guide until the desired grooves on the guide rods are even with
the biscuit joiner housing. The three grooves in the guide rods
indicate the correct settings for #0, #10 and #20 biscuits respectively.
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Figure
23-7.
Adjust the depth-of-cut setscrews to match the biscuit size
being used.
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Adjust both
depth stop setscrews (Figure
23-7), so that the guide cannot retract beyond the desired depth.
Next adjust
the two pins in the guide face and lock them firmly in place (Figure
23-8). These pins provide important kickback protection and
should penetrate about 1/32" in hard woods and 1/16" into softer
woods.
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Figure
23-8.
Adjust and lock pins to engage work during cuts.
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When using the
Mark V Model 510, position the worktable so the face of the biscuit
joiner guide is above the table insert (Figure
23-6). This will keep the leading edge of the stock from interfering
with the ribs in the worktable surface.
Finally, adjust
the height of the biscuit joiner. Press the stock against the joiner
fence until the blade is visible and adjust the quill until the
blade is at the desired height (Figure
23-9). Normally the biscuit location will be about midway
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Figure
23-9.
Use the quill adjustment to position blade for cut. Allow
clearance between biscuit joiner and worktable.
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between the
top and bottom, but higher or lower positions may occasionally be
desirable. The most important factor is that the cuts be at the
same height on both pieces of stock. When making these adjustments,
the quill should not be extended more than 3" and be sure to allow
clearance between the biscuit joiner arbor and the worktable in
order to prevent damage to the table surface. After all adjustments
have been made, turn on the Mark V and set the correct speed. Guide
the workpiece with your left hand until the biscuit centerline mark
on the stock is aligned with the engraved centerline on the biscuit
joiner guide. With a push block in your
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Figure
23-10.
Align biscuit centerline with joiner guide and use a push
block in your right hadn when feeding stock.
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right hand (Figure
23-10), press the stock slowly against the guide, compressing
the springs until the guide reaches the depth stops... then retract
the stock. Repeat this procedure for each cut on both pieces of
stock before changing the setup or height adjustment.
Panel Construction-
Panel construction or edge-to-edge joinery is one of the most common
woodworking operations. For best results, place the boards face
down next to each other and mark biscuit centerlines on the back
side. Then cut the biscuit slots and assemble the boards in this
face-down position to help assure a flat, smooth final surface.
Typically,
allow one biscuit for each foot of length in an edge-to-edge joint,
with a minimum of three biscuits. Space the biscuits evenly and
position the end biscuits at least 3" from the ends of the boards
so the boards will engage both of the pins in the guide when the
biscuit slots are cut.
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Figure
23-11.
On stock more than 1" thick, two biscuits may be used
for added strength.
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End Grain
and High Stress Joints- Because of the wood's high porosity,
end grain joints--such as T-Frame, L-Frame or End Butt--are almost
impossible to make with glue alone. Using biscuits will strengthen
these joints because the biscuits are glued face-grain-to-face-grain.
For best results,
use the largest biscuit available that will allow at least 1/4"
of stock at each end of the biscuit slots. On wide joints, such
as a T-shelf, use multiple biscuits, allowing as little as 1/2"
between biscuit slots.
On stock over
1" thick--especially on high stress joints such as a table leg and
skirt--two or more rows of biscuits may be used for added strength
(Figure 23-11).
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Figure
23-12.
When joining stock of different thicknesses a shim may be
used to eliminate adjustments and assure accurate alignment.
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When joining
stock of different thicknesses-such as a 1" thick skirt being joined
to a 2" square table leg-a thin piece of scrap wood or hardboard
can be used as a shim (Figure
23-12) to eliminate the need to make quill adjustments for each
thickness. This assures that the setback will be exactly the same
on all joints and that the biscuit slots will be aligned correctly
for easy assembly.
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Figure
23-13.
If the stock does not engage both pins, use your miter gauge
to maintain control of the workpiece.
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Short and
Narrow Stock- Workpieces less than 6" in width or length must
be handled with special care because the pins in the joiner guide
will not engage the stock and a kickback or injury is possible.
For these cuts, align the centerlines and lock the miter gauge into
the worktable to serve as a guide and stop. Hold the workpiece against
the miter gauge face and advance it slowly and firmly into the biscuit
joiner (Figure 23-13).
If you are
making multiple matching components--such as door frames or rails
and stiles for a cabinet front--you can make the setup once and
cut all biscuit slots quickly and accurately.
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Figure
23-14.
Use your miter gauge to hold and advance the stock on mitered
cuts. Do not slide the stock across the miter gauge face.
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Miter Joints-
For corner miters, mount the biscuit joiner so that it faces the
front of the Mark V with the guide perpendicular to the miter gauge
slots (Figure 23-14).
Adjust the worktable so one of the miter gauge slots is under the
biscuit joiner and the quill is extended 3" to avoid interference
between the safety grip and the Mark V's powerplant. Set your miter
gauge to 45° (or to match the angle of the miter), place your
workpiece against the miter gauge with the centerlines aligned,
and adjust the safety grip to hold the stock securely.
Make the cuts
by advancing the miter gauge and stock into the cut together. Do
not slide the stock across the miter gauge and into the biscuit
joiner as this will not produce an accurate cut. A piece of coarse
sandpaper may also be attached to the surface of the biscuit joiner
guide to keep the stock from creeping during the cut.
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Figure
23-15.
When working with large stock, mount the biscuit joiner diagonally
for maximum support of the workpiece.
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Edge Cuts
in Wide Stock- Working with large or wide stock is similar to
other edge joining operations, but additional support must be used
to give the operator control of the stock for accuracy and safety.
This is achieved by mounting the biscuit joiner diagonally, at about
a 30° to 50° angle to the miter gauge slots (Figure
23-15). With the Model 510, check your setup to be sure the
table height crank doesn't interfere with the stock.
If additional
support is needed, use the extension table system.
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