I plan on casting my own keel, And I want to use a bathtub as the
crucible { Like Glen Ashmore] My question is how is the elbow attached
to the Tubs drain hole? Also For the tub to hold the volume of lead
that I need, I need to plug the overflow hole. What would be the best
way ? Can I use firewood for the heat

I had the advantage of owning a metal turning lathe but you may be able to
cobble something similar together. I took a 2 x 2 1/2" pipe reducing bush
and turned down the hex to approximately fit the taper of the drain hole,
set it in Duraseal 1531 high temperature silicone putty and screwed a 2 1/5"
elbow on from below. You may have to trim off a little of the end of the
bushing or slip a couple of big washers on the bushing to get the elbow
tight against the bottom of the tub. Then ran some 2 1/2" pipe over to the
mold and added another elbow. The high temp silicone is important because
it stays reasonably flexible. Refractory cement will crack as soon as the
lead weighs down the pipe and you will get a spray of hot lead.

One thing I should have done is add another piece of pipe about 3" long to
the second elbow. The lead is going to come through the pipe amazingly fast
and when it hits that elbow it is only going to turn about 30 degrees and
spray everywhere but into the mold.

You can put about 4,000 pounds of lead in a standard 5' tub which is about
11 times as much weight as it was designed for so it needs to be well
supported on all edges and a couple of pillars down the middle. I used fire
brick set in refractory mortar for the pillars and set the tub in wet
mortar.

I suppose you could use wood but it will take a lot longer and tending the
fire under the tub supports will be a problem. With propane I could
completely close up the fire box and control the air. You want only enough
air to support the flame. Any extra does nothing but carry off the heat. I
fired it through holes in the drain end and had a couple of loose bricks at
the top of the far end that I could remove as needed to control the draft.

I made my burners from a couple of old vacuum cleaner motors and some 2"
pipe fittings. Just remember to start a pilot fire (oily rag) in front of
the burners first. Then turn on the blower and finally the gas. When
shutting down turn the gas off before the blower. If the gas comes on first
it will back up into the fan motor with somewhat undesirable results.

It only took about 20 pounds of propane to melt 4,000 pounds of lead but the
blowers require a pretty high rate of withdrawal so I used two 40 pound
cylinders on each burner to keep them from frosting up. The new OPD valves
may not allow fast enough withdrawal so it might be better to use a 100
pound cylinder. They are exempt from the valve requirement.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Hess cutter 56" wrote in message
ups.com...
I plan on casting my own keel, And I want to use a bathtub as the
crucible { Like Glen Ashmore] My question is how is the elbow attached
to the Tubs drain hole? Also For the tub to hold the volume of lead
that I need, I need to plug the overflow hole. What would be the best
way ? Can I use firewood for the heat

There is a very good description of the process in BOATBUILDING by Howard
Chapelle. Wood as fuel to melt lead is entirely satisfactory, it has been
used for years. Beware of using concrete blocks to support the tub;
firebrick is much better as suggested above. If you really want to cast a
keel larger than a bathtub can hold, finding a foundry may be a good (safe)
alternative.

What works against a wood fire is that it takes a pretty big fire and you
can't control the air so it waste a lot of heat. Melting a couple of tons
of lead is hot enough and skimming the dross without melting yourself can be
a real challenge.

The old guys casting ballast would rig a big iron pot beside the mold and
build a fire under it. When the pot was ready they knocked out a plug and
let her rip. That is fine for simple ballast but if you are casting a fin
you need to remove the dross to prevent weakening inclusions and more
control over the pour which means you have to get close to the pot.. I
would not have attempted my pour with a wood fire.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Dave W" wrote in message
...
There is a very good description of the process in BOATBUILDING by Howard
Chapelle. Wood as fuel to melt lead is entirely satisfactory, it has been
used for years. Beware of using concrete blocks to support the tub;
firebrick is much better as suggested above. If you really want to cast a
keel larger than a bathtub can hold, finding a foundry may be a good
(safe) alternative.

I like the Idea of using Propane Burners! There are some good examples
on The Backyard meatelcastimg web site. Glenn how much air { CFM]
do you think you where moving through the Burners? And what size
orifice ? Can you give me a more detailed deception of the Burner set
up? Thank You CW

My burners, starting from the business end, are a 1"x 1 1/2" female reducer
on the end of a 12" piece of 1 1/2" galvanized pipe. Then a Tee, 6" more
inches of pipe and a floor flange that the blower mounts to. The reducer
on the front end has four 1/8" holes drilled around the shoulder for a
little gas/air mix to leak out and make small stabilizing flames around the
main opening. A piece of 2" conduit slips over it to shield the little
flames. The side port of the Tee is bushed down to 1/4" with the threads
drilled out so a 1/4" nipple can be pushed through until the inside end is
just shy of the middle of the main pipe. It needs to be a pretty tight fit
so put a pipe cap on the end to protect the threads and hammer it in. The
gas hose fits to the other end.

I drove a couple of pipes into the ground at the drain end of the tub and
mounted the burners on them with a block of wood and U-bolts.

I already had the blowers salvaged from the solar wood kiln. They came
from Grainger
http://www.grainger.com/Grainger/wwg...mId=1611663777
They put out 60CFM but I ran them with the intake about half covered. You
have to adjust the propane regulator and the blower intake so the flame is a
loud steady roar. If the flame pulses or blows out you have to much air.
If it turns yellow you have to much gas for the air. Start with a clean
blue flame and gradually increase the gas until the flame gets a yellow edge
then open the air a little and slowly increase the gas until you see the
yellow again. Keep doing that until the flame starts pulsing and then turn
everything down a notch until it stabilizes.

Now start slowly closing up the vents on the other end of the tub until you
feel hot air coming back out around the burners and then open them up
slightly. Check the flame again and adjust so there is no yellow. Now you
have the burners working at their maximum output and only enough air needed
for combustion entering he firebox.

You might get by with a single burner but I melted 4,000 pounds in a little
over 90 minutes using two. I also had a couple of sheets of mineral fiber
cloth salvaged from a closed neon sign shop that I covered the tub with to
try and keep the heat in. It seems to have helped a little. You can also
use it to cover any openings in the sides to help control air flow. You
might be able to bum some used cloth from a neon shop. They use it to
sketch out tube designs and form the tubes on it. Once it gets to scorched
up they throw it out.

One more trick. Cut a fresh straight green stick about 1" thick off of a
nearby bush. Crape Myrtle is ideal. Strip the branches and leaves but
leave the bark. When the melt is about ready, stir it with the stick and
the stick will start to "sing". As the moisture in the wood boils out in
little microburst it sets up ultrasonic vibrations in the molten lead and
the dross will magically rise to the top so you can skim it off.

Needless to say the mold must be ABSOLUTELY DRY and ALWAYS remember, pilot
fire first, then blower and finally gas.


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Hess cutter 56" wrote in message
ups.com...
I like the Idea of using Propane Burners! There are some good examples
on The Backyard meatelcastimg web site. Glenn how much air { CFM]
do you think you where moving through the Burners? And what size
orifice ? Can you give me a more detailed deception of the Burner set
up? Thank You CW

Another alternative is to use a burner (or perhaps two for a big job)
from an oil furnace as a heat source. I bought three for $10 at a
country auction- lots of spares. You will have the blower/fuel pump
situation already worked out and the fuel is more compact and easier to
handle than propane. If you are pouring a substantial keel (mine was a
traditional-shaped 4200 pounder) it might be worthwhile to have a
melter welded up from steel plate. Then you can incorporate legs, etc
in the design. One of the early WoodenBoat mags had some details.
You might also want to have an oxy-acetylene torch on hand to preheat
the various spouts and pipe to make sure you don't get lead freezing
enroute to your mold.

Best to keep the whole operation quiet as the neighbours are apt to get
upset and blame their kid's defects on your lead project!

John

A second hand oil burner would be excellent if you can find one. Down here
in Georgia though they are hard to come by because everyone heats with gas
or electricity.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com