Manual of Purpose-Made Woodworking Joinery

Designing, setting out and making stairs 111

of any perceived ugliness or aesthetic appeal, add
greater strength and rigidity to the post. This is
because the post is supported higher up by the string’s
tenons and by the screwed end of the second riser. In
marking out the oblique stub- tenons, the position of
the shoulder line is determined by the key rule that
the face of the riser (marked on the strings from the
pitch- board) equals the centre of the newel. Therefore,
as indicated in Figure 6.38(a), the shoulder line is
marked back (into the string) at half the newel’s thick-
ness from the riser- face, then the tenon- projection
is marked forward at two- thirds the newel- thickness
from the shoulder line. After the bare- faced tenons
have been shouldered to thickness (usually 16mm for
a 28mm finished string), the double stub- tenons are
set out as shown below in Figures 6.38(a) to (e).

Removing tenon- cheeks from strings

Figure 6.38(b): The deep, oblique stub- tenon area – as
seen free of marking out at 6.38(b) – is reduced on the
step- side by 12mm to leave a bare- faced tenon area
of 16mm. This reduction can be done on a tenoning
machine, by using either the bottom- or top- tenoning
head – otherwise such a deep, oblique tenon is
awkward to reduce and various techniques are used to
achieve this, including: 1) Reduce the area to a 12mm
depth by a series of portable powered- router cuts; 2)
Cut the shoulder- line with a tenon saw, remove about
an 8mm depth of waste wood by chisel- chopping
across the short end- grain (providing the grain is
straight), then (having now produced a shoulder to
run against) remove the remaining waste down to the
gauge lines with hand tools such as a Stanley No.78
rebate plane and/or a No.073 shoulder plane, finish-
ing in mid- area with a Stanley 04 or 04½ smoothing
plane – or a 5½ jack plane.

Outer string

Inner (wall) string

Margin-line marks squared across from the wall string to the outer string, prior to pitch-board marking

Figure 6.37 This illustration of a pair of stair- strings positioned edge- to- edge highlights the method of transferring the hypot-
enuse divider- marks from the wall- string to the outer- string – and also shows the position of the outer- string’s tenons, which
have evolved from the pitch- board’s initial face marks – explained in the setting out details in Figures 6.38(a) to (e). It can
also be seen here (on the left) that the inner wall- string runs past the bottom newel- post tenons, this being for the inclusion of
a bottom bullnose- ended step that protrudes past the newel post.

Face of riser equals

centre of newel post

FFL

Top of

outer

string

16

12 28

Mark ½ of newel thickness

to establish shoulder line

Then go forward^2 ⁄ 3 of newel

to estsblish tenon projection

Figures 6.38 (a) to (f) The part elevations of the outer

string at the top- end, above a plan view of the newel post

and bare- faced, stub- tenoned string in- line below, shows

the step- by- step setting out of the oblique, double tenons

required. The same procedure for this setting out can also

be applied to the tenons at the bottom of this string. Note,

however, that when there is no protruding bottom step, the

outer string touches the floor and the tenon needs to be

divided by 4 instead of 3, to provide a base haunch. Note

also that, as shown at (f), these wide double- tenons theoreti-

cally should have a 5mm reduction at their extremities (back

to the shoulder line) to guard against the mortise holes

appearing via string- and tenon- width shrinkage. However,

to my knowledge, this is rarely done; partly because the top

edge of the outer string is covered with a grooved string-

capping (to receive the balusters) and partly because the

acute angle formed on the underside abutment to the newel

makes it virtually impossible to detect any shrinkage gaps.