Re: [bolger] lead mold
Gary,
A few more thoughts on casting lead. First, sealing can be accomplished with
high temperature silicone caulk of the type used to seal wood stoves and
chimney pipes. In the colder parts of the world this stuff is available in
any hardware stove. I have also used refractory cement in this application,
which should be available from a mason's supplier in small amounts. Second,
as has been said, once you cast SS rod into the lead, you will not be able
to get it out without destroying the casting. Another alternative for
providing channels in the lead is to use copper tubing with the correct
inside diameter and leave them in. If this dodge is employed, the tubing
should be filled with sand and sealed with silicone or refractory cement
prior to the pour. Yes, copper, like bronze, will form a galvanic couple
with the lead, but because the quantity of copper is so small and that of
the lead is so great, very little of the lead will be lost over time.
Copper tubing cored keel castings have been used successfully by John
Guzzwell, among others,
Good luck,
david
gbship@...wrote:
A few more thoughts on casting lead. First, sealing can be accomplished with
high temperature silicone caulk of the type used to seal wood stoves and
chimney pipes. In the colder parts of the world this stuff is available in
any hardware stove. I have also used refractory cement in this application,
which should be available from a mason's supplier in small amounts. Second,
as has been said, once you cast SS rod into the lead, you will not be able
to get it out without destroying the casting. Another alternative for
providing channels in the lead is to use copper tubing with the correct
inside diameter and leave them in. If this dodge is employed, the tubing
should be filled with sand and sealed with silicone or refractory cement
prior to the pour. Yes, copper, like bronze, will form a galvanic couple
with the lead, but because the quantity of copper is so small and that of
the lead is so great, very little of the lead will be lost over time.
Copper tubing cored keel castings have been used successfully by John
Guzzwell, among others,
Good luck,
david
gbship@...wrote:
> As part of the redesign of my 30-footer, Phil and Susanne have drawn
> up a winged centerboard. I'm working on the mold for the lead wings
> and have a couple technical questions. The mold (which must hold
> 1,000 pounds) is being built out of plywood (minimum 3/4 inch and
> perhaps thicker) and will be implanted in the the gound for extra
> support. It's about 3.5 inches deep at the deepest, and 3 feet long
> by 2 feet wide. What sealant should be used at the joints to prevent
> the lead from running out any cracks? Will epoxy vaporize in the
> heat? Will 3M 2100 work? A polyurethane glue?
>
> Secondly, a couple of stainless steel bars have to be cast into the
> lead so they are precisely placed. That means where they run through
> the mold in a couple places, there will have to be a sealant to
> ensure there's no lead leakage. Thoughts? But once the lead cools,
> the bars have to be driven out, so the sealant can't lock them in
> place. Right now, we think that normal shrinkage of the lead will
> make it fairly easy to remove the bars, but if anyone has
> thoughs/suggestions, I'd appreciate them. This is a job I only want
> to do once....
>
> If I can figure out how to do it, the keel/centerboard drasing may be
> posted in the vault. It's a beaut. This is replacing the fixed keel
> on my boat, for greater convenience in the Gulf of Mexico. (I'm also
> getting a higher and longer cabin, and a fold-down mast...)
>
> Gary Blankenship
>
> ------------------------------------------------------------------------
> Remember four years of good friends, bad clothes, explosive chemistry
> experiments.
>http://click.egroups.com/1/4051/10/_/3457/_/958365249/
> ------------------------------------------------------------------------
Gary:
If you cast SS bars in the lead, you will NOT get them out. Use wood, as
Peter has suggested, or go to a foundry, and get sand cores, or wrap several
layers of paper around the bars - this should add up to a thickness of .030"
per side. You don't want to do the whole thing twice, but you could pour a
small piece to test various coring methods.
One other thing to be careful about, is moisture in the mold. It needs to
be very dry, or steam generated on pouring will be explosive. If the ground
is damp, it can affect the mold. Best to keep the mold dry, and bury it at
the last minute.
Chuck
If you cast SS bars in the lead, you will NOT get them out. Use wood, as
Peter has suggested, or go to a foundry, and get sand cores, or wrap several
layers of paper around the bars - this should add up to a thickness of .030"
per side. You don't want to do the whole thing twice, but you could pour a
small piece to test various coring methods.
One other thing to be careful about, is moisture in the mold. It needs to
be very dry, or steam generated on pouring will be explosive. If the ground
is damp, it can affect the mold. Best to keep the mold dry, and bury it at
the last minute.
Chuck
> As part of the redesign of my 30-footer, Phil and Susanne have drawn
> up a winged centerboard. I'm working on the mold for the lead wings
> and have a couple technical questions. The mold (which must hold
> 1,000 pounds) is being built out of plywood (minimum 3/4 inch and
> perhaps thicker) and will be implanted in the the gound for extra
> support. It's about 3.5 inches deep at the deepest, and 3 feet long
> by 2 feet wide. What sealant should be used at the joints to prevent
> the lead from running out any cracks? Will epoxy vaporize in the
> heat? Will 3M 2100 work? A polyurethane glue?
>
> Secondly, a couple of stainless steel bars have to be cast into the
> lead so they are precisely placed. That means where they run through
> the mold in a couple places, there will have to be a sealant to
> ensure there's no lead leakage. Thoughts? But once the lead cools,
> the bars have to be driven out, so the sealant can't lock them in
> place. Right now, we think that normal shrinkage of the lead will
> make it fairly easy to remove the bars, but if anyone has
> thoughs/suggestions, I'd appreciate them. This is a job I only want
> to do once....
>
> If I can figure out how to do it, the keel/centerboard drasing may be
> posted in the vault. It's a beaut. This is replacing the fixed keel
> on my boat, for greater convenience in the Gulf of Mexico. (I'm also
> getting a higher and longer cabin, and a fold-down mast...)
>
> Gary Blankenship
>
>
>
> ------------------------------------------------------------------------
> Remember four years of good friends, bad clothes, explosive chemistry
> experiments.
>http://click.egroups.com/1/4051/10/_/3457/_/958365249/
> ------------------------------------------------------------------------
>
>
>