Danderdude
07-10-2012, 12:35 AM
It stopped raining enough this afternoon to try firing up my smelting rig to turn a bunch of soft lead sheeting into ingots. The last run I made ended up ruining my cruddy aluminum muffin pans, so I decided to try my hand at making a pair of wooden ingot molds.
Last week I grabbed 4 scrap 2x6 cutoffs I had laying around, one pair 18" long, the other 24". One would be left whole and serve as the bottom of the mold, while I sawed up the other with a circular saw set at 30 degrees. Everything cut easily and fit back together as well as could be hoped. Wood glue was applied to all the wood-on-wood contact surfaces, holes were drilled and screws were screwed. There was nary a crack or seam that water could leak from, much less lead, or so I thought. Even so, I only estimated a 1 in 3 chance of working.
One set was designed to make small pyramids, while the other was to make long sticks.
Fast forward to this afternoon. I lit my propane-fired smelter, which still works so darned well I can't believe I built it myself, much less from scrap and junk, and had around 80lbs of molten lead ready to pour in 10 minutes. The ingot molds held up! They worked! The slow smoldering of the pine and sap bubbled up through the slowly cooling ingots and bathed me in satisfaction. I topped the pot off, dumped the first set and poured the second.
The first thing you'll realize is that lead doesn't just take a lot longer to cool in a wooden mold... it takes a WHOLE LOT longer. In my impatience, I picked up the stick-style mold and slammed it on the ground. I was met with a beautiful splattering of lead coating the bermudagrass, as the still-molten cores of the ingots blew out the sides. Then the remainder just didn't want to drop out. It took slamming the mold onto concrete to release the hollow husks, and it was quickly evident why: the thin parts of the wood, where two pieces meet, char back much faster than the bulky parts.
And here are the molds after three pours each.
http://i.imgur.com/Wi4YG.jpg
As the moisture cooks out of the wood, the pieces shrink, and substantially. If it tries to shrink around a screw shank, it just splits.
http://i.imgur.com/0l15k.jpg
As the wood shrinks, the thin edges allow molten lead to flow under and around them, burning them faster than the rest and recreating an hourglass shape rather than a nice, easy to release ingot.
http://i.imgur.com/XoNu8.jpg
In the end I had to revert to using my lone Lee ingot mold and a bucket of water to quickly cool it.
The pyramidal ingots came out to 3.5-4lbs a piece, and the sticks weigh out at 4lbs.
Moral of the story: Wood might make a decent ingot mold, and certainly a cheap one, but this isn't how you do it.
http://i.imgur.com/OJp5T.jpg
Last week I grabbed 4 scrap 2x6 cutoffs I had laying around, one pair 18" long, the other 24". One would be left whole and serve as the bottom of the mold, while I sawed up the other with a circular saw set at 30 degrees. Everything cut easily and fit back together as well as could be hoped. Wood glue was applied to all the wood-on-wood contact surfaces, holes were drilled and screws were screwed. There was nary a crack or seam that water could leak from, much less lead, or so I thought. Even so, I only estimated a 1 in 3 chance of working.
One set was designed to make small pyramids, while the other was to make long sticks.
Fast forward to this afternoon. I lit my propane-fired smelter, which still works so darned well I can't believe I built it myself, much less from scrap and junk, and had around 80lbs of molten lead ready to pour in 10 minutes. The ingot molds held up! They worked! The slow smoldering of the pine and sap bubbled up through the slowly cooling ingots and bathed me in satisfaction. I topped the pot off, dumped the first set and poured the second.
The first thing you'll realize is that lead doesn't just take a lot longer to cool in a wooden mold... it takes a WHOLE LOT longer. In my impatience, I picked up the stick-style mold and slammed it on the ground. I was met with a beautiful splattering of lead coating the bermudagrass, as the still-molten cores of the ingots blew out the sides. Then the remainder just didn't want to drop out. It took slamming the mold onto concrete to release the hollow husks, and it was quickly evident why: the thin parts of the wood, where two pieces meet, char back much faster than the bulky parts.
And here are the molds after three pours each.
http://i.imgur.com/Wi4YG.jpg
As the moisture cooks out of the wood, the pieces shrink, and substantially. If it tries to shrink around a screw shank, it just splits.
http://i.imgur.com/0l15k.jpg
As the wood shrinks, the thin edges allow molten lead to flow under and around them, burning them faster than the rest and recreating an hourglass shape rather than a nice, easy to release ingot.
http://i.imgur.com/XoNu8.jpg
In the end I had to revert to using my lone Lee ingot mold and a bucket of water to quickly cool it.
The pyramidal ingots came out to 3.5-4lbs a piece, and the sticks weigh out at 4lbs.
Moral of the story: Wood might make a decent ingot mold, and certainly a cheap one, but this isn't how you do it.
http://i.imgur.com/OJp5T.jpg