Tuesday, February 22, 2011

Not Quite Led Zeppelin...

...would you believe, Lead Keel?  Companionway to Heaven?  No?  Doesn't have quite the same ring to it.  At any rate, I have started to pour lead into my keel. This process has been a little more troublesome than it really has needed to be.  More on that later.

Before starting the pour, I have some cleanup to do.  A bit of work with the belt sander cleaned up some drips from the glue-up.  I then took my router and rounded over forward edges of the centerboard trunk.  These edges will be exposed in the cabin, so it is good to make them nice and smooth.  I also rounded over the bottom edge of the keel, which will come in handy much, much, much later in the build, when the bottom of the hull get sheathed in fiberglass.

Test fit of the centerboard.  It slides in and out really nicely.

I screwed down a plate of plywood to one side of the cavity in the centerboard to enable the pouring of lead into it. 

I also took advantage of the keel assembly being light enough to lift onto the workbench to round over thebottom of the keel and the edges of the centerboard trunk that'll be exposed in the cabin.

I bought a small propane burner to melt the lead on.  I lit 'er up, filled my pot with the lead shot that I had purchased online, and waited.  And waited.  And waited.  The lead started to melt maybe a little, but never  really developed into a pourable pool of molten metal.  I tried for longer than I probably should have (the timescale is measured in hours).  Unfortunately, the little burner just didn't have BTU's to get the job done.  Also, the pot I'm using just isn't thick enough to hold the heat, so anything not directly exposed to the flame just wouldn't get hot.

I rectified the BTU problem by switching to an electric hotplate that I bought a while back for use in a steam box.  This little guy could melt the lead ok, but the pot is still a limiting factor.  Right now I'm just planning to live with that.

The next problem is with my lead.  When I ordered the lead shot online, I ordered the "unwashed" variety (they also sold "washed").  Big mistake.  There is so much gunk that floats up (carrying with is unmelted lead shot) that it really makes it difficult to get all the shot melted.  Right now my method is dump in a bunch of shot, melt it as much as possible, spoon off the gunk and whatever unmelted shot that go along with it into another container, pour the molten lead, and then drop the stuff I spooned off back into the pot to get as much of the rest of the lead out of it as possible.  This works ok, but is a little frustrating and time consuming.

At any rate, I've started pouring the lead.  I have the cavity in the centerboard filled, along with the area of the keel  forward of the centerboard (actually, a little overfilled in one spot) and have make 20lbs of the requisite 91 lbs in the compartment aft of the centerboard trunk.  I had to stop a little early today because, of all things, it started snowing in the middle of my smelting fun.  It is supposed to snow the next few days too, is the lead pour is now on hold for a little bit.

My first lead smelter.  This propane burner was too wimpy, so I switched to an electric hotplate.

Suited up and ready to go

The keel set up outside, ready for lead.

The lead shot, ready to melt

Melting underway.  Anything not silvery is dirt and dross

Adding lead to the forward compartment..

Getting lead into the aft compartment.   Still have a long way to go.


There were some gaps and voids in the lead pour in the centerboard that had to be filled with thickened epoxy before the centerboard can get 'glassed. 
Filling the gaps on one side
Filling the gaps in the other

One more minor setback/problem.  I've decided that I'm not really happy with all of my scarf joint.  My plane-cut scarf for the keelson turned out perfect.  My chicken-out, jig-cut scarfs for the panels...well...didn't.  At least the ones in the boards that became the lower side panels just ugly along one edge.  The strength seems ok, but there are just gaps in the veneer.  After assessing the situation carefully, I decided to do the only logical thing and fill the gaps with thickened epoxy.  I'll sand it smooth once it's dry.  Hopefully that'll fix the problem.  I haven't inspected the other panels, but I wouldn't be surprised to find similar issues there. 

Filling the gaps in the scarfs.
It'll probably be a few weeks before I start stitching the hull together, but it is definitely getting closer.  And exciting.  I'm looking forward to it.

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