The lead bulb for the keel was made by sand casting – a technique developed in the Bronze Age.
(Everything I do here is dangerous!)
The bulb model was 3D-printed in two symmetrical parts. The first part is placed on a flat surface and prepared to be buried in “green sand”.
The other half of the plastic model is perfectly aligned with the first half. The surface is lightly dusted with a powder-based release agent and again, the part will be covered with green sand.
Both plastic parts have been released from the sand molds. Now the molds can be joined together and the cavity between them will be filled with molten lead.
The lead is being melted in electric casting pot and poured into the sand mold.
Goodbye my dive weights!
Here’s the baby!
Another casting done in the same way.