Marking and setting out tools 13Pictorial Projections
Figures 2.9(a)(b)(c)(d): Other forms of orthographic
projection are known as pictorial projections. These pre-
serve the three- dimensional view of the drawn- object,
but have a limited value in the makeup of working
drawings. However, the 3- D value is very useful for
illustrations and for making explanatory freehand
sketches more easily understood. Figure 2.8(c) above
(of the bench- hook sawing block) is a pictorial view
known as an isometric projection. It is repeated below at
2.9(a) for comparison and is formed with 30° and 90°
angles to the horizontal plane. Even when graphically
explaining technical points to somebody, using a picto-
rial projection to guesswork angles in freehand sketches,
will serve well in illustrating your point of explanation.
There are three other forms of pictorial projec-
tion, all of which come under the heading of oblique
projections. First, at Figure 2.9(b) is an oblique cavalier
projection of the bench hook; which requires true-
shaped front elevations and true- sized side- and plan-
views drawn at 45°. By this method, objects tend to
look disproportionate. The second, at Figure 2.9(c) is
an oblique cabinet projection, which is made up of true-
shaped front elevations with its side- and plan- views
at 45°, but scaled to only half their true depth. This
half- depth technique makes the object look strangely
true and proportionate. And for this reason, it rates
second place to the isometric projection. The third, at
Figure 2.9(d) is an oblique planometric projection (often
wrongly referred to as axonometric), which has its front
elevation drawn at 30° and its side elevation at 60°;
this produces a true- shaped plan view.MARKING AND SETTING OUT
TOOLS
These vary according to what item is being marked- or
set- out and they include the following, ranging from
most- used to least- used:
● A sharp, ordinary HB or 2H pencil for general
marking and setting out. The pencil- point can be
conically pointed, or chisel- pointed.
● A sharp, chisel- pointed, medium- grade leaded
carpenter’s pencil, if preferred to a marking knife for
marking shoulder lines; note that joiners usually
sharpen pencils with a sharp, bevel- edged chisel,
safely pointed away from their hands and body,
whilst the pencil rests in the crotch of their free
hand’s thumb and forefinger.
● A sharp marking knife, for marking shoulder
lines (especially on hardwood and quality- softwood
jobs).
● A large try square with a 230mm blade, for squaring
shoulder lines, etc, on the joinery components or
for square- marking from the face- edge of a rod.
● An adjustable combination mitre square with a
300mm blade; note that by holding a pencil’s point
against the end of the adjusted blade, with the pencil
and blade- end supported by the middle finger of the
hand not holding the square’s stock, this tool can be
used as a pencil- gauge (pencil- liner).
● A 610 × 450mm steel roofing square (for use as a
large try square on setting out rods); and a pat-
ented, aluminium square- fence attachment that is
fixed to one of the square’s outer edges, for convert-
ing it into a more easily- used try square.
● A traditional, purpose- made hardwood pencil- liner
(also called a runner), that acts as a pencil- gauge
for running pencil- lines parallel to the face- edge of
setting out rods.
● A good- quality steel retractable tape rule of at least
5m length; note that, because of the loosely- riveted
metal hook protruding at the blade’s end, a practical
technique in using these rules is needed for precise
marking or setting out. For example, if setting
out a standard 1 981mm door- height section on
a rod or door- stile edge, I would recommend that
the hooked end be used only as an anchor, pulled
against the end of the rod or stile to hold the rule
taut whilst marking – and not as the start of a
measurement. Then, after making the initial pencil
mark to clear the hooked- end area, cumulative30º 30º 45º(a) (b)
Figure 2.9 (a) Isometric projection (b) Oblique (cavalier)
projection.
45º 30º 60º(c) (d)
Figure 2.9 (c) Oblique (cabinet) projection (d) Oblique
(planometric) projection.