The Shop > Metal Stuff
New lining for the iron furnace
vtsteam:
That's Plan C. :dremel:
I might do a furnace run-up to check for leaks today if precipitation holds off.
vtsteam:
I made up some new small molding boxes to do a piston casting. Smaller boxes are easier to roll, and use less sand, so I can mold two at once from the same pattern with the 50 pounds of sand I have.
vtsteam:
Wooden flasks don't last long when pouring iron. Generally it happens when there's an overflow from the sprue basin that reaches an edge, or a spill at the edge, or often just touching the crucible to the edge of the flask while pouring. Generally the rest of the box suffers less. It's mainly the top edge where the crucible is being poured from.
I do have some steel flasks that I built years ago. They are heavy and, as in this case, they aren't always ideal for the shape of the pattern you want to pour. So it's easy to quickly put some wooden boxes togetherfor a special need, but it would be nice if they lasted longer. Their light weight makes molding easier, particularly if the pattern is tall or large and you have to roll a few times.
I've thought about keeping the lightt weight of wood but adding more heat resistance by inlaying a flat metal edge. Better would be a channel shape, Though that would need to be flush with the wood on all three edges. So, it's impractical.
Then this morning I thought, why does the metal protector have to be attached to the flask? Just use a piece of heavy angle iron,cut to size and lay it on top of the pouring edge after the mold is made up. That will protect the edge the side, and also stop any sprue overflow. Adds weight, too when it's needed, Simple!! :doh:
And that's just what I did.
btw. poured iron today........
tom osselton:
I was going to mention that to protect the wood. I’ve never painted my boxes but do have places on the sides to bolt both sides together in case of separation on larger pours.
vtsteam:
I did a third iron melt in a week today. I timed it at 15 minutes from start to melting 6 lbs of iron in an A6 crucible, and with slagging and ferrosilicon addition, plus bringing it up to pouring heat, it was 21 minutes total from lighting the furnace.to pouring iron.
I used about a gallon of diesel fuel for that, now in winter, when heavier oils would not flow or atomize as well. I'm guessing there's enough heat in the furnace after to probably do a zinc melt with no more fuel, or an aluminum or brass melt within a few minutes of lighting up again. I imagine a second iron melt might be 10 minutes more.
This same furnace and same burner, with 4" of firebrick and ganister insulation took 1-1/2 to 2 hours to pour iron 9 years ago, and those were borderline hot enough sometimes.
The only problem I've had so far is that a small piece of the lid blanket, (which was pieced together from leftovers of the main furnace lining), has come loose twice. That didn't happen during a melt, but after cooling. The blanket tends to shrink a litlle after an initial melt, and where once it was packed in place at the edges, it loosens. I did cement all edges with sodium silicate, per Ironman's video, and covered the joints with the hot face compound, but the blanket still shrank and loosened.
Today I put positive retaining in by screwing with self tapping metal roofing screws from the sides of the lid into the looser blanket pieces. I hope that holds better.
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