Agriculture Reference
In-Depth Information
at the expense of handpicked rubbers selected out of a general firing, creat-
ing unique tones and textures that were important in creating the cut, rubbed,
and gauged work of previous centuries. The tendency to fire rubbers at higher
temperatures is also of concern, not only for the loss of any pozzolanic benefit
that diminishes markedly beyond 900ºC (Baronio and Binda, 1197, 41), but
also for those wishing to continue executing traditional hand-crafting skills on
soft rubbing bricks.
The move by some brick companies towards using mechanically cut and/
or abraded rubbers for on-site assembly has led to the production of a harder
brick. This enables it to withstand the spinning force of a cutting disc or pro-
filed carborundum wheel, whereas a soft rubber would lose its all-important
sharp arrises with the high-speed air vortex created by and ahead of the cut-
ting or abrading heads. From an economic point of view, the softer rubber,
ironically, causes excessive wear on these tools.
Several other brick or building product companies advertise the supply of
machine-cut voussoirs for gauged arch sets for on-site assembly or as gauged-
faced lintels. These are either a brick of their own or one from another sup-
plier; some of which have a tenuous claim to being an authentic rubber.
A lot of designers today use computer-aided design (CAD) programs rather
than the time-tested geometrical methods of setting out and establishing work-
ing templets for arches practised by experienced craftsmen. This can be used
successfully but can and does sometimes lead to on-site assembly problems.
Although CAD can be used to produce full-size drawings for templets or set-
ting out, careful checking for accuracy should always be undertaken before use
and in consultation with the designer.
Tests on the efficacy of the use of CAD drawings for fine gauged work was
undertaken by architect Simon Douch with the author, alongside a traditional
drawing of elevation, plans and section of the small-scale niche (see Fig. 171).
From the CAD drawing the necessary templets were obtained and the results
were very good, but as Mr Douch emphasised the all-important accuracy in
the use of CAD is dependent on the quality of the computer software and the
level of knowledge and skill of the designer operating the system. In respect of
the accuracy of a computer print-out, from which to obtain precise templets,
it is dependent on both the quality of the software and hardware of the system
employed.
Gauged work demands accurate drawings from which all necessary informa-
tion can be obtained by the cutter and setter. It is unforgiving of error and
any deviation, especially when working to finer traditional tolerances, as these
become exaggerated if the setter tries to build-out the mistake.
Bricklayers can sometimes find that delivered pre-assembled units do not
fit precisely together and resort to rubbing-up individual bricks to resolve the
problem. This should never be done as, after due consideration, one might
