Manual of Purpose-Made Woodworking Joinery

Designing, setting out and making stairs 129

handrails. The face- mould template is first used to

mark the basic wreath- shape on the plank’s planed

face- side – and it should be laid diagonally so that

the unavoidable short grain is equally distributed and

square prism (a, b, c, d) with its top surface inclined
to the known stair- pitch angle. If you can imagine
the true, marked quadrant- shape of the prism being
sawn around vertically with a bandsaw, the shape that
that would produce on the inclined top- surface would
be a true quarter ellipse (as drawn here), equal to the
inclined centre- line of the wreathed handrail. And this
quarter- ellipse is also equal to the un- drawn centre-
line of the above face- mould template.
Figure 6.58(d): To set out the handrail wreath,
reference was made to the original rod and the plan
view of the wreathed string, (Figure 6.53(c)). The
centre line of the string was drawn, as illustrated,
with the required quadrant- shaped width of the
handrail added. The central quadrant was then boxed
in with a plan view of the square prism marked a, b,
c, d. From centre a, a quadrant was struck to the left
to end on an extended line from b. With b as centre,
a semi- quadrant was struck from d to the same
extended line. As shown, the two left- hand lines
were extended up to a so- called X- Y line separat-
ing HP (the horizontal plane) from VP (the vertical
plane) and the other two were extended up further
into the vertical plane. The stair- pitch line (C) was
drawn on the left until it struck the line extended up
from a, to create the bevel required for the wreath.
From this point, horizontal line (B) was formed. Line
(A) was then drawn to create the important trapezoi-
dal shape which provided the three lengths (at A, B,
C) of the axes for the quarter ellipse required to draw
the face mould.
Figure 6.58(e): With reference to Figure 6.58(d)’s
trapezoid, to develop the face- mould template’s shape,
the length of inclined line (A) was measured and
drawn horizontally in the development below. Next, a
compass was set up to represent the length of inclined
line (C) and arcs were struck above and below line (A);
first, above from the left extremity of line (A), then,
below from the right extremity. A similar technique
was used for trapezoid line (B) and, again, arcs were
struck above and below line (A), but from the opposite
ends to intersect with the arcs struck previously. Lines
B^1 C^1 B^2 C^2 were drawn carefully through the arcs
to form the rectangular prism. Lines B^1 and C^1 were
the axes for forming the two quarter- ellipses of the
face mould by the short- trammel method (illustrated
in Chapter 8: Geometry for Curved Joinery). Lines B^2
C^2 are marked on the face mould to identify the posi-
tion of the wreath’s central tangents.

Making the twisted wreath

Figure 6.59: The piece of thick (or built- up) timber
for the wreath should be straight- grained, knot- free
and, obviously, of the same species as the adjoining

Newel cap

dc

a

A

VP

HP

B

*

*

*

C

Pitch

Bevel

required

b

Figure 6.58 (d) The geometrical development of the

widest width of the face- mould template at the three aster-

isks and the lengths of the face- mould axes at A, B, C.

Initial plank/wreath

thickness each end

C' B'

A

Face

B Mould

(^2) C^2
B' is the semi-
minor axis
C' is the
semi-major axis
Figure 6.58 (e) The development of the face- mould tem-
plate and – as seen in the top left corner – the develop-
ment of the wreath’s initial plank thickness by applying the
plumb bevel through the drawn handrail’s centre line.