How to make a jack plane
Practical Action
Making planes
All woodworking planes have a number of similar elements, and if you are to make a plane
that works well then you need to understand the function of each element. This applies to
plough, rebate, moulding, smoothing and jack planes.
The sole: Unless the plane has been designed
for curved work, the sole must be straight and
flat. It is very difficult to produce a straight
surface if the sole of the plane is twisted or
bowed.
The mouth: The mouth of the plane is where
the blade passes through the sole. It should
be as narrow as possible if the plane is to
leave a smooth finish. When downward
pressure is applied to the plane, the front of
the mouth helps to prevent the workpiece
splitting ahead of the cutting edge.
needed to form a split.
The frog
A large mouth allows the split to develop,
and will leave a rough surface on cross-
grained timber (see below). A well-placed
cap iron will also help to give a finer finish
by breaking the fibres in the shaving and
taking away the strength that would be
The throat
Shavings leave the plane through the throat. On a
jack plane this is the opening at the top of the
stock. It is essential that this opening is large
enough for the shaving to pass through easily, or
the plane will ‘choke up’ and require constant
clearing. A common fault is that the fixing device
is placed too close to the front of the throat.
On all jack planes the width of the throat should be
3mm wider than the width of the blade to allow it
to be adjusted laterally.
The fixing mechanism
Whichever method is used to hold the blade to the
frog, it must be held securely but also allow a certain
amount of adjustment. (This version of the jack plane
will use the crossbar and wedge.)
The blade
This must be straight and flat to fit tightly onto the
frog. The cutting edge must be ground to an angle of
25 degrees or there will be no clearance behind the
cutting angle.
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