Monday, August 09, 2010

Get the Lead Out

My second try at a rudder was a big improvement. It's amazing how the details matter, if you put too much pressure on a wedge on one side, then you cut a little deeper with the router. More sanding to do later.

The blade is now glassed, and I'm adding a few extra coats of epoxy. The rest of the rudder assembly is under-coated. This will be my first chance to see how the Paint turns out.

Since the center board is next, I did a trial pour of a lead sink weight. I cut a 1 1/2" hole in 3/4" inch ply, and clamped a backing board with a thin sheet of metal (from the base of a biscuit tin) behind the hole. I melted the lead shot in a cheap saucepan bought for the job. I wore a leather welders apron, leather gloves and a full face shield.

A simple propane camping gas hob easily melted the shot, and the pour went very easily. A bit of an anticlimax. (that's not a bad thing when you are playing with molten lead)

Since I was just running a test, I did not bevel the hole for the lead, and indeed, it shrank as it cooled, and then later simply fell out.

The other thing that I learned was that the metal sheet, aimed at giving me a flat base on the lead, failed miserably. The back of the lead was concave. I guess the metal was too thin, or perhaps the plating on the metal off gassed as the lead was setting. There's some evidence of bubbles. Given a tin plating on the metal from the biscuit tin, that's my best guess right now.

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