Agriculture Reference
In-Depth Information
No matter what shape was used the basic cutting techniques for the bricks
remained the same, and it was here, in the cutting shed provided for this pur-
pose, that the old-time bricklayer jealously kept from his less fortunate work-
mates the art of setting-out, preparing templets, cutting and gauging the arch.
Initially the arch had to be drawn out, full-size, so either individual templets,
or a single and longer 'running templet' could be obtained. In general, only
half the arch needed to be drawn, as the other half was a mirror image. Also
from the drawing the exact number of voussoirs could be determined, the size
of joint, the soffit as well as the extradosial bevels, or the correct curve to the
extrados of the voussoirs. As stated earlier, some arches like the straight (and
its development the camber arch) and the Venetian, or Queen Anne, had a dif-
ferent shaped voussoir for each position, every brick having a different bevel.
This would only apply to one half of the arch, as each voussoir would have
its mirror image in the other half. Therefore it was necessary to number each
brick related to its position and indicate its side and to set the voussoirs out on
the scaffold in order of use.
The setting, or building, of a gauged arch could be accomplished in different
ways according to the situation and number of similar arches needed on a job.
If the arch were large or with voussoirs having each soffit bevel of a different
shape then they were sometimes assembled in small sections in the cutting shed
and then joined together to complete the arch over the opening. If the façade
of the building had many similar arches, as was common, then all the arches
might be complete assembled inside wood jigs. These were then raised into
position over the openings for which they were ultimately intended. The jig was
left securing the arch until it was bonded with mortar into the face: the tech-
nique resembled that of the modern lintel, in that there was no delay on the
progress of the building while the arch was constructed in situ and hardening.
Generally though the method most favoured was to construct the arch in
situ . In this instance the temporary timber support, or centre, was checked for
position, level and plumb, and then the intrados position of the voussoirs were
obtained from the full-size drawing and transferred and marked-out upon the
support; and the all-important centre line too. Lines were then erected across
the opening where the arch was to be turned from the main walling to ensure
the arch would be constructed flush; or perhaps a little proud to allow for it
being so after the final rubbing-up. Also a line, or a thin batten was fixed to the
radius, or striking point, of the arch centre to check that the joints were normal
to the curve and that the extrados height was maintained. Another common
practice, to ensure the accuracy demanded with gauged work, was to erect a
temporary timber beam above the arch, upon which the centre line and all the
voussoir positions were carefully set out, called a 'profile tree'. Nails were then
fixed against these lines to which lines from the striking point could be strained
to accurately line-in each consecutive course. If there was an inaccessible striking
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