Sand Casting Marine Hardware and Other Useful Skills

Sand casting is a metal casting process characterized by using sand as the mould material. It involves the pouring of molten metal into a cavity-shaped sand mould where it solidifies. The mould itself is made of sand particles held together with an inorganic binding agent. After the metal has cooled to room temperature, the sand mould is broken open to remove the casting.

In this latest episode, Kevin Carney, Shop Director at the famed Apprenticeshop in Rockland, Maine for over 30 years, will demonstrate the safe, fairly easy steps to producing castings free of defects. The process of sand casting starts with a simple form and casting sand. The form is made up of two small plywood boxes with the top (cope) and bottom (drag ) keyed in some fashion so that they align when stacked.  Sand is packed in the lower part, the pattern (a wooden facsimile of the piece we want) is pressed into the sand up to a parting line. Powder is applied to ensure the pattern and top part of the mould don’t stick together. The top part of the form is positioned on the bottom half. Sand is packed in this upper section. Once well packed, the top form is lifted, the pattern is removed, leaving a void for the molten metal to fill. A channel (sprue) is made in the top part of the form for the molten metal to flow into the cavity. Vents are added where needed to prevent  air from being trapped in the cavity, and the two parts are stacked and ready for pouring. Silicon Bronze is heated to approximately 2,000 degrees in a crucible inside a furnace and is then poured into the mould through the sprue. The mould is left to cool at which time the two parts are separated exposing the finished piece.

The entire set up that Kevin uses in this episode is one that the viewer can easily put together at home. He’ll explain the function of each tool and where they can be purchased or some made from scratch. Practice makes perfect and as one becomes more confident in their sand casting skills over time, he or she will discover, with pleasure and satisfaction, that they can become their own teacher.

As a bonus, Kevin also takes time to demonstrate to our viewers how to deal with knots in the woods you may be working with. In addition, A-shop boatbuilding instructor Owen Page shares his techniques for making and inserting bungs and how to accurately cut and fit gains in your lapstrake planking.