Another lightweight fiber blanket furnace

Tobho, good job, you are like the traveling bell maker spreading your expertise!

Not to derail Tobho's thread, but I poured electrodes for a sinker EDM from copper when I was fiddling with the Indian Heads. I think It was HT1 that mentioned crushed glass as a cover but I just dedicated a small crucible for a test pour and cast a couple of shaped pieces. I'll try to get photos later.

 

On rereading my post was a little direct, that was not intended. I have read how hard copper is to cast but has not been my experience. I wound up with a lot of copper and started making ingots to save space. It does oxidize without flux.

http://forums.thehomefoundry.org/index.php?threads/my-new-favorite-photo.672/

 

Saves fuel too.
After seeing the numbers from ironsides, I knew you would get excellent performance out of a very low mass furnace.
Interesting casting for sure.

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I poured these to make a rocker arm for the Indian. I used the one for about an hour and reached the depth indicated by the black discoloration and then decided it was a waste of time cutting bar stock and I could speed up the operation by CNC ing a rough profile before forming the piece. Then never finished.
The pattern was Bondo in petrobond sand and cleaned up in the blast cabinet. I did a little Dremel work to improve the surface on the interior and restore what I might have lost in the shrink. As I mentioned I think the cover flux was ground glass and as I remember it poured similar to cast iron, very fluid.
I had to machine the stem for the holder and do not remember any problems with that either.

 

This is sort of on track for your build—-encouragement that you are on the right track.

I took my old lightweight lid apart today. It was just two layers of 1” wool and Satanite. The wool and Satanite survived well EXCEPT where the chimney I have to use forced hot gas around the vent liner and past the edge of the wool. There the metal covering failed and caused collapse of the area around the vent. But that was not due to some fundamental problem with the wool lining. It is true that the Satanite flaked off some with each firing but it was so easily patched that the flaking was only a minor nuisance. Some of that flaking was due to poor design on the chimney support I used on that lid. That is why i completely redesigned the chimney, the seal around the chimney and extended the vent liner and improved the lid lift mechanism. Inadequate lifting of the lid lifter contributed to the collapse too as after quite a few melts I was at time accidentally dragging the Satanite over the edge of the furnace. Satanite does not like that.

 

ESC: Could you give a little more explanation, I can't understand what you are showing. Did you cast iron in a copper mold?

 

Andy, these are electrodes for the EDM. The rocker in the center is an original and probably forged steel. It was the last part I needed to have a complete reproduction head for the 1914 Indian. The electrodes were also my first pure copper castings. I had poured Silicon Bronze for the domes and so had ventured into some of the copper alloys before did these.

 

Thanks, I glossed over the EDM reference. Very cool. When was this?

 

http://www.alloyavenue.com/vb/showthread.php?11532-1914-Indian-V-twin-heads&highlight=Indian

I think I quit posting when PB jerked us around, but now the photos show.
I crewed on the 2016 Cannonball run with 100+ motorcycles built prior to 1916 from Atlantic City N.J. to Carlsbad , Ca. I cast heads and domes for the 1914 Indian we ran.

 

You may be able to eliminate the propane preheat entirely.
I don't see the need for propane, but I would have to review your burner setup again.

I have seen several people operate furnaces indoors with a solid lid and a rear exhaust out a vertical stack.
This is something that will not be forgiving, and should something go wrong, ie: insufficient ventilation; leaks in the system, etc., and the carbon monoxide get too high, you won't get a second chance to correct the problem.
For a big open shed with ventilation, it could easily be done.

And don't forget you can get into a low oxygen situation too if you don't have adequate combustion air introduced from outside into the space, if the space is somewhat air tight.

Your furnace is looking good.

Edit:
I watched some of the video.
You may be able to switch to diesel right after turning on the propane.
The downside of a very short preheat may be that if the furnace is not quite hot enough, you may get dribble and diesel on the bottom and sides of the furnace.

My guess is that with a rag with diesel on it in the furnace, and some combustion air turned on, you could omit the propane entirely, but it may not be a perfectly clean start.

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I'd sure hate to be without my propane. Sometimes it's handy to just warm stuff up.

Now, if we have a "casting on a desert island with no tools" challenge...

 

Hey, sounds like a throwdown challenge to me.
Which island did you have in mind?
Tropical would be best.

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I was actually thinking Gilligan's Island. Or Fairway Rock.

 

Jeff, fire that first layer before adding more.