Manual of Purpose-Made Woodworking Joinery

Designing, setting out and making stairs 109

the housings would be cut by hand methods (referred

to as ‘trenching’) and two more templates would be

required. The first, illustrated in Figure 6.35, is a tread

template, which includes the nosing shape, the exact

projection past the face of the riser and the wedge

shape. The second template in Figure 6.35 is for the

riser, which also includes the wedge shape. The tem-

plates’ lengths purposely exceeded the actual width of

the treads and risers slightly, beyond the bottom edge

of the strings to enable the marking out of the hous-

ings to run- off the edge.

Template details

Even though only the pitch- board template described

at 6.34(d) above is likely to be used nowadays for

marking out the stair strings prior to attaching a stair-

case jig, it should either be made with good- quality

6mm plywood, a dense grade of 3mm hardboard, or

4mm MDF. It must be carefully prepared to shape

and size, as accuracy is vital in setting out – especially

with a pitch board; even 0.5mm more or less in riser-

height will have a cumulative effect of a 7mm error on

the total rise of a stair with 14 risers.

The top of the pitch- board above the margin allow-

ance must be fitted with a double, wooden fence – as

at 34(d) – to rest against the top edge of the strings.

The fence material, of not- less- than 20 × 20mm

prepared sectional size, can be glued and pinned, or

screwed – but must be accurately positioned in rela-

tion to each other.

Margins

Figure 6.34(d): The margin indicated in Figures 6.34(a)

to (d) is a variable measurement, usually set at not-

less- than 50mm, but it is dependent on the width

of timber being used for the strings and the edge-

treatment required, if any, on the top edge of the inner

Preparation of material for steps

After selection of the timber and the necessary
machining – including surface- and thickness-
planing – the treads and riser boards should be cut
accurately to length. This can be done by hand or on
a dimension saw- bench, if available. The edge treat-
ment of tongues and/or grooves and the nosing- shape
is next. Again, these can of course be done by hand
with a variety of traditional planes, otherwise a vertical
spindle moulder machine or a heavy- duty portable
powered- router is needed.

Preparation of Strings

Figure 6.35: Next, the inner and outer strings need to
be prepared for housing or trenching to receive the
steps. Traditionally, in the absence of powered routers,

Figure 6.34 (c) The combined pitch- board and margin
template; and (d) the updated version of the pitch- board,
made of thin plywood, hardboard or 4mm MDF. Note
that the extended rise- and going- edges allow the pencil
to run on and – once the pitch- board is moved to the
next consecutive step- position – the crossed lines create a
better intersection at the critical extremes of the hypotenuse
on the margin line.

Margin

line

Margin

Going

R

i

s

e

(c) (d)

Figure 6.34 (e) An isometric impression of a Trend ‘A’

plastic- laminate staircase jig clamped in position on a

marked stair- string, ready for the step- housings to be

formed with a heavy- duty portable powered- router.

Tread template

Riser template

Allow 9 mm sloping to 15 mm

for wedge, then use same

angle for shorter riser

template to avoid using

different shaped wedges

at the assembly stage

Figure 6.35 Over- long Tread- and Riser- templates.

(e)