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Oil fired crucible furnace

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This is an extension of the Sawed Off Cupola thread I started earlier, since that furnace is no longer being tried as a single charge charcoal cupola.

Its now an oil fired crucible furnace, so I thought it deserved a new thread.

Recent events:

Yesterday I had a missrun in pouring the mold  -- the pour was cold. The burner I made wasn't able to feed fuel at a high enough rate to get the iron fluid, though it did melt. Three hours of heating finally resulted in the fuel running out and  forced pour. The result -- no casting, only a sprue.

Today I took the burner off of the furnace and checked it out. The same burner more or less had successfully melted my first iron a couple weeks ago, but that one leaked oil. The burner was a Kwikie burner design. This atomizing burner was set too far back in the pipe housing in a 4" thick refractory lining (by design), so the spray impinged on the pipe walls and dripped out.

I re-built it with a longer and larger diameter spray tube extension that brought the nozzle 2" closer to the furnace barrel. Otherwise the design was unchanged. But new delivery problems arose -- traced at first to a bad silver braze joint. With that repaired I tried yesterday's melt. That was the missrun.

Today, after taking it out I couldn't see anything wrong with the burner. So I figured that the nozzle was just screwed in too close to the jet orifice to allow enough fuel to pass. I opened it a quarter turn and re-installed in the furnace. The difference was dramatic! It was back to being a jet engine!

So with that worked out at 3:30, I thought I'd give it another try before dinner. I broke up some cast iron, loaded the crucible and fueled the burner with an container of old diesel fuel -- about 3 gallons worth that I found in the shed.

The burn went great! I molded up a flask while the furnace was heating, with a very healthy roar. I had to stop the burn a couple times to add iron, as I couldn't fit it all in at once. I needed about 7 pounds for this casting.

Finally the metal seemed readyafter dipping a rod in and having it come out pretty clean -- a little thin shiny slag and that was it.

When I went to lift the crucible, it stuck to the wall and plinth, and I couldn't get the tongs around it. The crucible seemed fairly plastic -- temps must have been high! Finally I maneuvered it off of the wall, but carried the plinth out with it. When I set it down in  the sand to skim off the slag the plinth released, and I pushed it out of the way. it was then easy to lift it in  the shank and pour. Very fluid this time, I filled the mold, and still fluid the excess splashed a little out of the ingot mould while pouring.

Great pour! Man iron is exciting! A real high to get it to melt and fill a mold.

All in all, it took an hour and a half exactly from lighting the furnace until the pour was done. I'm sorry I didn't measure the fuel beforehand, but I think it took around a gallon or gallon and a half. Just a great day!  :ddb:

Pictures when I can get them up.

Plinth comes free of crucible ...

The pour....

All in, time to shut it down....

The shake out.....


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