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Construction Notes |
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The
Dome
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| I
started with this because I knew it HAD to be
made from fibreglass as there was no other
practical way, and I thought - it's a nice
simple shape to practice on - you know,
straightforward, no awkward shapes to work
around - HAH! |
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| The
former was made from 3/8" MDF with a copper
strap 'hinge' which slotted over a 1/2" dowel
fixed vertically to the baseboard. This allowed
the former to rotate 360 degrees, forming the
required shape of the dome as I built up layers
of plaster. |
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| The dome
plug was made up from a wire mesh/paper mache
base and built up using old plaster until the
shape of the dome was achieved. Unfortunately
the plaster plug would not sand down to a fine
enough finish. |
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| As luck
would have it, the plug wasn't the right
diameter anyway, so I was able to clad it in P40
fibreglass filler and remake the former to the
correct profile. The finished plug was sanded to
a fine finish with 600 grit wet & dry and given
a coat of G4 sealer and a final light sand down
with 1200 grit wet & dry. |
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| To make
the mould, the plug was given repeated coats of
Carnuba mould release wax, each coat being
buffed before applying the next. |
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| Then it
was time to make the mould - this was done by
applying a coat of PVA release agent, followed
by a thick coat of yellow gelcoat to the plug,
and 25mm around the base to form a lip for
stability and to create a level edge when making
the final casting. |
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| When
dry, a layer of fibreglass tissue mat was laid
in, using yellow pigmented resin, and built up
with coarse mat to a thickness of around 1/8". |
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| This
turned out to be the easy bit - separating the
plug from the mould was a different matter - the
lip I had created certainly retained the shape
of the plug, but it limited the flexibility of
the mould - in other words it was well stuck in!
- It took over an hour to separate using a well
tried method called "ooops I dropped it" (loads
of times) |
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| The 2005
series dome has indented lines and panels
around. These were added to the mould in
reverse, using 3mm plastic 'D' strips and 1mm
plasticard sheet. |
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| Once
these were in place, the mould was given a good
polish with Carnuba wax and prepared for lay-up.
I had difficulty in keeping the mould steady
(being a dome it's not surprising) so wooden
feet were fitted to the base. |
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| A coat
of PVA release agent was applied, followed by a
thick even coat of black gelcoat. When this was
touch dry, a layer of fine tissue mat was
applied with black resin, followed by 4 -5
layers of coarse mat, again using black
pigmented resin. |
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| When
cured, 25mm angle brackets were added for the
later mounting of the dome's inner ring. These
were fibreglassed in place with resin and coarse
mat. |
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| In an
attempt to 'melt' the release agent and wax and
release the cast from the mould it was immersed
in warm water - didn't work! - Eventually, I had
to cut through the mould's lip in order to give
some flexibility to insert wooden wedges and
release the cast. |
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| When it
finally came away I was delighted to see that it
was so good it needed no touching up - it was so
good I didn't even bother painting it. |
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Go to Part 2
- Dome Cowl and lights |
