314 Section 4 Manufacturing Process Database
This sequence of operations is often followed
when jointing. If the stock is narrower than the
jointer’s cutterhead, the jointer is normally used
to plane the surface and edge of the best face. The
opposing face is then planed on the planer, and the
board is cut to width on the circular saw.
Jointers are sized by the length of the knives in
the cutterhead. A small jointer, as shown in Figure 21-5,
might have a cutterhead with three or four knives,
and run at a speed of approximately 4500 rpm.
When a jointer is used to true an edge, the
operator places the face of the stock against a fence
(adjustable stop running perpendicular to the cutter-
head axis) and rests the edge on the infeed table of
the machine. This will ensure that the finished edge
is perpendicular to the face. The stock is pushed over
the rotating cutterhead and on the outfeed table. See
Figure 21-6.
After the back end of the stock passes the cut-
terhead, a machine guard closes the opening over
the cutterhead. On small jointers, a push stick is
normally used to hold down the stock and push it
through the machine. A larger jointer is shown in
Figure 21-7. With this machine, the stock is of suf-
ficient thickness and width to permit the operator to
push it through the machine without using a push
stick.
All of the major parts of the jointer—the infeed
table, outfeed table, and fence—can be adjusted to
produce the desired cut. The adjustment of the out-
feed table is very important. The outfeed table must
be positioned so that it is level with the highest point
of the knife edges. If the table is too low, the trailing
edge of the board will drop down, producing a dip
on that end of the stock. If the outfeed table is too
high, it will push the board upward and produce
a taper. In order to remove stock on the jointer, the
depth of cut is established by adjusting the infeed
table to a level that is lower than the outfeed table
and the knives on the cutterhead.
If it is not used properly, the jointer can be a
dangerous machine. Stock must be at least 12″ (30 cm)
long and at least 3/8″ (9.5 mm) thick. End grain
should never be planed unless the stock is at least
Figure 21-5. A small jointer of the type used to true the
edges of boards.
Figure 21-6. Cross-sectional view of a typical jointer.
Stock is held against the fence and moved over the rotating
cutterhead for material removal. The heights of the infeed
and outfeed tables are independently adjustable.
Fence Wood stock
Infeed table Outfeed table
Cutterhead
Figure 21-7. This machine operator is facing one side of a thick
board, using a jointer. The dark-colored mechanism pressing
against the edge of the workpiece is a spring-loaded guard that
swings into place to cover the rotating cutterhead as soon as the
workpiece has cleared it. (Delta International Machinery Corp.)
Guard
This sequence of operations is often followed
when jointing. If the stock is narrower than the
jointer’s cutterhead, the jointer is normally used
to plane the surface and edge of the best face. The
opposing face is then planed on the planer, and the
board is cut to width on the circular saw.
Jointers are sized by the length of the knives in
the cutterhead. A small jointer, as shown in Figure 21-5,
might have a cutterhead with three or four knives,
and run at a speed of approximately 4500 rpm.
When a jointer is used to true an edge, the
operator places the face of the stock against a fence
(adjustable stop running perpendicular to the cutter-
head axis) and rests the edge on the infeed table of
the machine. This will ensure that the finished edge
is perpendicular to the face. The stock is pushed over
the rotating cutterhead and on the outfeed table. See
Figure 21-6.
After the back end of the stock passes the cut-
terhead, a machine guard closes the opening over
the cutterhead. On small jointers, a push stick is
normally used to hold down the stock and push it
through the machine. A larger jointer is shown in
Figure 21-7. With this machine, the stock is of suf-
ficient thickness and width to permit the operator to
push it through the machine without using a push
stick.
All of the major parts of the jointer—the infeed
table, outfeed table, and fence—can be adjusted to
produce the desired cut. The adjustment of the out-
feed table is very important. The outfeed table must
be positioned so that it is level with the highest point
of the knife edges. If the table is too low, the trailing
edge of the board will drop down, producing a dip
on that end of the stock. If the outfeed table is too
high, it will push the board upward and produce
a taper. In order to remove stock on the jointer, the
depth of cut is established by adjusting the infeed
table to a level that is lower than the outfeed table
and the knives on the cutterhead.
If it is not used properly, the jointer can be a
dangerous machine. Stock must be at least 12″ (30 cm)
long and at least 3/8″ (9.5 mm) thick. End grain
should never be planed unless the stock is at least
Figure 21-5. A small jointer of the type used to true the
edges of boards.
Figure 21-6. Cross-sectional view of a typical jointer.
Stock is held against the fence and moved over the rotating
cutterhead for material removal. The heights of the infeed
and outfeed tables are independently adjustable.
Fence Wood stock
Infeed table Outfeed table
Cutterhead
Figure 21-7. This machine operator is facing one side of a thick
board, using a jointer. The dark-colored mechanism pressing
against the edge of the workpiece is a spring-loaded guard that
swings into place to cover the rotating cutterhead as soon as the
workpiece has cleared it. (Delta International Machinery Corp.)
Guard