More centerboard weight

Before I glued in the centerboard weights I put them on the scale to see how far off my target of 22 lbs I ended up.  I found they weighed 20 1/4 lbs, which was not too far off.  However, I decided that at this stage I could easily get closer than that, and by doing so I wouldn't always have a nagging feeling that I was a little light in the centerboard!

I had gathered up a bunch of the lead shavings from the initial machining (see one of the first posts in this blog), and I melted those down with a propane torch and a little cast iron ladle I picked up at an antique store once.

I drilled two test holes with Forstner bits, 3/4" and 1", and filled them with lead.  I then weighed the slugs and calculated how many I would need to make up the 1 3/4 lb deficit.  I ended up needing about 20 of the larger size, so I drilled 10 holes in each of  the two halves of the centerboard to a depth of about 5/16".

And poured them full of lead.  I had shavings enough for only about half the job, so I melted the remainder off of one of my leftover ingots by putting it in the flame and catching the drips in the ladle.  That worked out smoother than I expected.

One job for tomorrow is to scrape these down to level, and then these halves will be ready for assembly.

Graphite pinholes, centerboard fairing and weights

I had noticed as I had been coating the inside of the centerboard case parts with epoxy thickened with graphite that there were some places that weren't taking the epoxy.  I don't know why that happened.  I thought they would fill on subsequent coats, but they didn't.  

Probably not a big deal, but I wanted a smooth surface in these areas that would be inaccessible once assembled.

I sanded the shine off to make the spots more visible, mixed up some epoxy/microballoon fairing mix, and filled in the little holes.  Hopefully the filler will adhere OK and will give a smooth appearance when I add the next coat.

Tonight I also finished up the fairing work on the centerboard and rudder pieces.  I used a homemade longboard as well as the random orbit sander.  These pieces are now ready to be covered with fiberglass after the halves are glued together.

And to get another step closer to that, I glued the weights in the centerboard.

Rudder weights glued in

Tonight the various pieces I had epoxied last evening were not cured enough to sand.  I did a little hand sanding on one side of the centerboard, but needs to cure further.  Since the fairing work on the rudder halves is about done I decided it was time to epoxy in the weights, so I did that with some thickened epoxy. 

And then I did another coat of epoxy/graphite  on the two pieces that make up the centerboard case.  I coated over what I had done last night without sanding.  I think since the previous coat is not fully cured that I'll get good adhesion.

This is as much as I will have time for before Jan 1.  Happy New Year!

Trimming weight

I spent much of the day today trimming down the centerboard and rudder weights.  The top surface is not smooth as poured and if there is extra lead the halves don't fit together well.

The lead is soft and can be worked with woodworking tools like scraper, bench plane, etc., but that's a lot more work than I thought it would be.

I resorted to my old Atlas shaper to do the job.

I had to reposition the weights to get the parts that were under the clamps.  And the centerboard weights exceeded the capacity of the machine, so had to move them around a couple times.

Here's a shot of the underside of a centerboard weight as poured.  I ended up filling in some of the larger voids with fresh lead.

This whole process took a lot longer than I had hoped, and it will be good to have it all glued together.

Lead Pour - centerboard and rudder

Thanksgiving Day in the shop - I worked today on adding lead ballast to the centerboard (22 lbs) and the rudder (2 1/2 lbs).  The latest plans addendum was published just in time.

Starting with the centerboard, I used a large calipers to verify the thickness, marking the 13mm contour so the router would not break through at a depth of 10mm.  

I calculated how much space was needed and built a template for the router out of one of the offcuts from the kit.  I fastened the the template on with 1/2" pins driven with my Cadex 23 gauge pin nailer, which worked great.  When done, the template pulled off, leaving the pins, which I pulled with a pliers.  I cut to a depth of 10mm and left an island in the middle so the router wouldn't dive in, and later put a big base on the router and removed the island.

I did the same for the rudder, but cut these only 7.5 mm deep.

I got out my little aluminum foundry and fired it up to melt the lead.

Fun to pour metal...

There must be a bit of moisture in the plywood, as the lead bubbled and boiled.  This was a much bigger issue on the centerboard pours which have a lot more metal in them.  

Due to the bubbling, there are some voids in the underside that I may fill in after I get things smoothed out and check the final weight.

So, I'm happy with this progress today!