|Dave has written to tell me that he uses a far different
process than the one I’ve described -- which was more oriented toward model
makers who cast a great deal in situ – such as Navis/Neptun. But we will
let Dave's word's tell the story:
“Something I forgot to mention, all our moulds are taken directly from the master, it has proved to be so robust that there is no need to use submasters, though I have 5 perfect castings set aside should I need them."
Using the master to make a mold is unusual, and may have something to do with how the mold is formed in this case. The photographs show the basic master Dave used, and the molds made from it. Dave tells us exactly how he makes his molds for the Lion:
"This might surprise you, but the Lion is cast from a single mould which ensures no join lines. I've not found the need to use a multiple mould yet. The difficulty is removing the casting without damage, especially with opposite facing undercuts from the upper pom-pom mounts and the deck section the mast protrudes through. By filling from the bottom there is no need to worry about any air escaping.”
“The hull, when cured, is mounted in a jig, aligned via the turret holes
and machined flat. Smaller models can be smoothed with sandpaper/wet and
dry. If I added more detail to the hull like the fwd funnel and bridge
section I would then have to use a multiple/split mould. I've attached
some photos of a mould and one showing the underside of a casting after
|It is difficult to make out, but one can see portholes,
deck fixtures, and superstructure bits. The mold's flexibility allows the
casting to be removed, but as Dave indicates -- getting the undercuts out
must be very difficult indeed. Once again, Dave tells us in his own
words how he molds small parts:
"The smaller mould will give people an idea of using a simple mould to make multiple identical pieces for the master. This one has the star, which was used to test multiple pre-production masts, a liferaft, needed in various locations, and the searchlight platform needed for the fwd and aft funnels. Just for interest I've cast a hull in black resin, I'll add all the fittings in light grey. It will give a good graphic illustration as to the breakdown of the master."
I want to thank Dave for sharing this material. We seldom get to see this side of the game!