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