Chapter 21 Processes Used to Separate Wood Materials 323
Boring
In the furniture-making industry, holes are often
bored for inserting dowels (wooden connecting
pegs) in parts such as drawers or shelves. In such
applications, perfect alignment is necessary. This
is normally accomplished using a boring machine.
While boring machines look something like conven-
tional drill presses, they are much heavier and often
have several spindles. This enables more than one
hole to be bored at a time.
With some single-spindle boring machines, the
table moves upward toward the tool. In other instances,
the table is stationary and the spindle moves toward it.
Often, the travel of the tool is regulated by a foot pedal,
as is the case with mortisers and punch presses.
Multi-spindle boring machines are normally
available in sizes up to 6′ long. There may be as many
as twenty spindles on large production machines.
Mortising and Tenoning
Sometimes, an odd-shaped joint called a
mortise-and-tenon joint is required to secure
drawer components or other pieces of fine furniture.
The vertical mortising machine cuts the rectangular
opening in wood for a mortise-and-tenon joint. See
Figure 21-24. The mortise-and-tenon joint provides
much more holding strength than a simple right-
angle butt joint, where two pieces of wood are
pressed together in a 90º angle, glued, and nailed.
Most furniture joints are secured with screws,
dowels, or biscuits (flat discs). These approaches are
inexpensive but eventually result in wobbly chairs
or weak products. Screws provide the weakest joint,
and dowels create a loose joint through expansion
and contraction. Mortise-and-tenon joints, with one
piece chiseled to fit into a slot cut in another, are the
mark of fine furniture.
Mortising Machines
Only the mortise is cut on the mortising
machine. The mortising machine looks like a large
vertical drill press or boring machine. The major dif-
ference is that the stock is advanced into the chisel,
rather than the chisel being advanced into the work.
The hollow mortising chisel is carried in a vertical
spindle, somewhat like the drill press. The outside
rectangular shape of the mortise is cut with the
chisel, while the inside is cleaned out with the mor-
tising bit. The bit turns inside of the chisel, making
the hole and removing chips. The chips travel up the
spirals of the bit and flow away from the bit through
an opening in the front of the chisel. See Figure 21-25.
To cut a mortise, the mortising chisel and bit are
placed in a bushing, and then locked in place in the
spindle with setscrews. The stock is clamped to the
table, and a mark showing where the first mortise is
to be cut is lined up properly beneath the tool. After
the depth of cut is set, the machine is turned on.
When the operator depresses a foot pedal, the table
moves up, and the mortising tool immediately cuts
the mortise. When the pedal is released, the table
retracts. The process is repeated until the mortise is
the correct size.
Oscillating-chisel mortising machines are
available in single- or multiple-head models. Some
machines can operate either vertically or horizon-
tally. Multiple-head machines can be equipped with
as many as twenty mortising heads.
Tenoning Machines
The square mortise is of little value without a
machine to cut a tenon. The tenon is cut on a ten-
oning machine, often called a “tenoner.” Single-end
and double-end tenoners are used in industry to cut
tenons for products such as window sash rails. They
are also used to shape shoulders and to cut corner
joints for cabinets.
Figure 21-24 Mortise-and-tenon joints. The protruding
tenon, or tongue, is inserted in the mortise. The mortise can
be cut all the way through or partially through the wood.
Blind
Mortise-and-Tenon
Joint
Through
Mortise-and-Tenon
Joint
Figure 21-25. Mortising chisel for use in a drill press. The
square cutter cuts the mortise and the drill inside removes
the chips. (American Machine &Tool Co.)
Boring
In the furniture-making industry, holes are often
bored for inserting dowels (wooden connecting
pegs) in parts such as drawers or shelves. In such
applications, perfect alignment is necessary. This
is normally accomplished using a boring machine.
While boring machines look something like conven-
tional drill presses, they are much heavier and often
have several spindles. This enables more than one
hole to be bored at a time.
With some single-spindle boring machines, the
table moves upward toward the tool. In other instances,
the table is stationary and the spindle moves toward it.
Often, the travel of the tool is regulated by a foot pedal,
as is the case with mortisers and punch presses.
Multi-spindle boring machines are normally
available in sizes up to 6′ long. There may be as many
as twenty spindles on large production machines.
Mortising and Tenoning
Sometimes, an odd-shaped joint called a
mortise-and-tenon joint is required to secure
drawer components or other pieces of fine furniture.
The vertical mortising machine cuts the rectangular
opening in wood for a mortise-and-tenon joint. See
Figure 21-24. The mortise-and-tenon joint provides
much more holding strength than a simple right-
angle butt joint, where two pieces of wood are
pressed together in a 90º angle, glued, and nailed.
Most furniture joints are secured with screws,
dowels, or biscuits (flat discs). These approaches are
inexpensive but eventually result in wobbly chairs
or weak products. Screws provide the weakest joint,
and dowels create a loose joint through expansion
and contraction. Mortise-and-tenon joints, with one
piece chiseled to fit into a slot cut in another, are the
mark of fine furniture.
Mortising Machines
Only the mortise is cut on the mortising
machine. The mortising machine looks like a large
vertical drill press or boring machine. The major dif-
ference is that the stock is advanced into the chisel,
rather than the chisel being advanced into the work.
The hollow mortising chisel is carried in a vertical
spindle, somewhat like the drill press. The outside
rectangular shape of the mortise is cut with the
chisel, while the inside is cleaned out with the mor-
tising bit. The bit turns inside of the chisel, making
the hole and removing chips. The chips travel up the
spirals of the bit and flow away from the bit through
an opening in the front of the chisel. See Figure 21-25.
To cut a mortise, the mortising chisel and bit are
placed in a bushing, and then locked in place in the
spindle with setscrews. The stock is clamped to the
table, and a mark showing where the first mortise is
to be cut is lined up properly beneath the tool. After
the depth of cut is set, the machine is turned on.
When the operator depresses a foot pedal, the table
moves up, and the mortising tool immediately cuts
the mortise. When the pedal is released, the table
retracts. The process is repeated until the mortise is
the correct size.
Oscillating-chisel mortising machines are
available in single- or multiple-head models. Some
machines can operate either vertically or horizon-
tally. Multiple-head machines can be equipped with
as many as twenty mortising heads.
Tenoning Machines
The square mortise is of little value without a
machine to cut a tenon. The tenon is cut on a ten-
oning machine, often called a “tenoner.” Single-end
and double-end tenoners are used in industry to cut
tenons for products such as window sash rails. They
are also used to shape shoulders and to cut corner
joints for cabinets.
Figure 21-24 Mortise-and-tenon joints. The protruding
tenon, or tongue, is inserted in the mortise. The mortise can
be cut all the way through or partially through the wood.
Blind
Mortise-and-Tenon
Joint
Through
Mortise-and-Tenon
Joint
Figure 21-25. Mortising chisel for use in a drill press. The
square cutter cuts the mortise and the drill inside removes
the chips. (American Machine &Tool Co.)