Manual of Purpose-Made Woodworking Joinery

Jointing Casement Frames and Sashes 67

tenoning machine) to fit the ovolo- moulded shape.
The other difference is that haunching spurs and
franked haunches do not fit easily into machin-
ing operations, so these would be common tenon-
haunches mortised into the stiles – as shown at (a).

(a) (b)

Figure 4.13 (a) Sash stile mortised and haunched to
receive a tenon with a machine- scribed shoulder; and (b)
Sash stile mortised, ovolo partly removed and haunching
spur formed to receive a minimal hand- scribed shoulder.
Note the end- grain removal for wedges, which should be
done by hand after mortising, to approx one- third of the
tenon’s thickness, sloping to not- more- than two- thirds of the
tenon’s depth.

(c) (d)

Figure 4.13 (c) The inner shoulder of the tenoned jamb
is machine- scribed to fit the ovolo- moulded sill; and (d)
the inner shoulder of the tenoned jamb is hand- scribed to
fit the ovolo- moulded head. Note the position and size of
the mortise- and- tenons: they are governed by the rebate
and formed in the thicker part of the components – and
do not conform to the third- of- thickness rule. The above
mortise- size is scaled at 22mm, an approx quarter of the
overall thickness.

above for sashes. One variation, though, is that the

relatively narrow jamb tenons into the sill and the

head were left in their full width and not haunched.

This was possible because horn- projections were

traditionally left on the sills and the head (to be

built- in to the brickwork). Nowadays, the horns are

removed and these un- haunched joints would require

strengthening with draw- bore dowels. Figure 4.13(c)

indicates machine- scribing and (d) indicates hand-

scribing.

Hand- scribing technique

Figures 4.13(e)(f )(g): The hand- scribing technique

for fitting ovolo- (and other) moulds to each other in

right- angled, obtuse- or acute- angled internal corners

is simply based on the shoulder- end of the moulding

being first mitred (at 45° for right- angles, or other

bisected angles for obtuse- or acute- angled intersec-

tions). The mitring of a moulded shape produces

the elongated profile to be removed by chisel- paring

with a scribing gouge and (occasionally) bevel- edged

chisels. The illustrations below show the inner shoul-

der of the tenoned casement- jamb marked and mitred

by chisel- paring with the aid of a mitring template –

and the mitred profile scribed out by vertical paring to

about 3 or 4mm below the ovolo- quirk on the jamb’s

face- edge.

Frames

Figures 4.13(c)(d): Because the frames are ovolo-
moulded and rebated, the techniques of mortising,
tenoning and scribing are similar to those described

(e)

(f)

(g)

Figure 4.13 (e) A hand- made hardwood mitre- template

(similar metal types are widely available) positioned for

mitring the jamb’s ovolo mould. This is done by graduated

bevel- edged chisel- paring against the template, working

back from the top, shouldered corner to the final position

shown in the illustration; (f) the completed mitre, ready for

scribing; and (g) the scribed area removed by graduated

vertical- paring with an in- cannel scribing gouge and a

firmer – or bevel- edged – chisel.