Issue 48 AUG 25 web - Flipbook - Page 71
Gillingham using their 5-axis CNC machines. This
provided a consistent and accurate reproduction of the
original finials.
Fabrication of Brass Brackets
The internal brass brackets presented the greatest
fabrication challenge. After reaching out to multiple
casting specialists—none of whom could accommodate
non-ferrous metals—we decided to machine the brackets
from solid brass using 5-axis CNC technology. Each of the
40 brackets was individually cut, taking several days of
precision machining.
Once received, the bracket ends were fluxed and soldered
to enable proper adhesion with lead during casting. Using
a graphite casting block, lead was poured around the
brackets. We then spent an additional two days meticulously cleaning off heat marks caused by the soldering
process.
Assembly and Welding
With Code 8 lead as the base and rear structure, we
worked with a local engineering shop to machine the
edges for a straight finish. Their metal folder was adjusted
to accommodate the thickness of the lead and to prevent
material thinning, allowing for precise bending to the
required angle.
We then:
• Welded the brass brackets to the back of each lead base.
• Lifted and positioned the cast lead faces.
• Welded the faces in place with six welding passes with
a No. 5 tip torch.
• Chamfered external weld areas to allow for shaving
flush, ensuring a clean, flat finish without compromising
the structural integrity.
Formation of New Lead Pipes
As part of our ongoing commitment to high-quality
ornamental leadwork, we also undertook the formation
of new lead pipes to accompany both the restored and
newly fabricated gutters. Although we’ve produced many
bespoke lead pipes and hoppers since our establishment,
each project presents its own set of design and fabrication
challenges that continue to push and refine our
craftsmanship.
For this project, precision and visual consistency with the
original period features were essential. To achieve this, we
collaborated with our local engineering shop to produce
a custom aluminium casting mold, designed specifically
to replicate the original shell-pattern fixing heads. This
mold was co-designed to be bolted and unbolted with
ease, allowing for the safe removal of each newly formed
lead component without damage or distortion.
We selected Code 8 lead as the base material, ensuring
both the structural integrity and longevity required for exterior architectural applications. Each pipe was formed
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