The Shop > Metal Stuff
Sawed off cupola
vtsteam:
Backside when first broken out -- you can see the channel from the greensand core -- also how very close I was to running out of metal in this pour! The sprue was full when poured, and did shrink down on cooling -- but I don't want to cut it that close again!
Total metal loaded in the crucible was 5 pounds. Total weight of casting and sprue was 4 pounds 3 ounces. I don't know where the other 13 oz. went as I didn't scrape a lot of slag, just a reasonable amount. Maybe I mis-measured?
Also -- just checked the iron with a file -- it files "like buttah". Nice grey iron.
dsquire:
Steve
I'm glad to see that all your hard work and research has paid off. The anticipation of knowing it is going to work but not having proved it yet can get the adrenaline flowing.
Thank you so much for taking the time to document all of the steps that you have taken to get to this stage of casting iron. For many it was a very good lesson in back yard DIY casting. I have enjoyed following along and will continue to look for more posts on this and other subjects.
Good luck and pour safe. :D :D
Cheers :beer:
Don
vtsteam:
Don, thanks!
And on the "pour safe" well wishes, -- very apropos -- I do want to point out that it was just a test, and I plan to rebuild most of the burner assembly since what I have here is clearly temporary makeshift. I don't favor open plastic tanks, clear vinyl fuel line, my present loose mounting plate with a couple of screws, etc. But in the interests of a preliminary test It was handy to see the fuel flow and change from kero to waste oil, etc. I don't recommend anyone else copy what I did today.
I'll be improving the whole setup -- and in fact making an improved burner as this one could be better in some respects. Also a new blower, mount, tanks, and better ducting and plumbing, now that I know it works.
And of course, I haven't yet succeeded with charcoal, the original intended fuel, or as a cupola. I'm still going to take a shot at that.
vtsteam:
Worked on improving the oil burner today.
One problem with the Kwiky burner on this furnace is a result of its construction. The oil orifice is located in a Tee fitting and a leg of that fitting comes out of the burner tube and connects to the oil supply. What this means is that the orifice is located right at the outer skin. The leg prevents you from pushing the burner nozzle further in.
My furnace shell and lining is 4" thick, so the atomized jet has to travel 4" in to reach the furnace interior.
The original Kwiky also has a nice small size tube housing -- 1-1/4" in diameter. And this size suits the size of the 1/8" plumbing fittings to center the orifice in the tube in a very simple manner.
The problem for me comes because of the long distance and narrow diameter of the tube. The orifice effectively sprays a fan, hitting the tube walls, and spray condenses there and flows down into a drip. That effectively defeats a lot of the purpose of an atomized spray. Probably half of the oils is simply dripping into the furnace, or, worse dripping back out along the bottom of the pipe, unless it is oriented downhill inwards.
The designer of the Kwiky also noted a drip and mentions orienting the tube down and in.
I decided that I wanted to extend the orifice away from the oil inlet tee almost all the way into the furnace so that the spray pattern does not hit the walls of the housing.
The problem with extending with 1/8"pipe is that the tee gives lots of clearance for the oil, but the 1/8" pipe does not -- it is a fairly close fit to the 1/4" copper tube airline which runs inside, concentric with the oil flow.
Here's a pic of the air line inside the oil line:
vtsteam:
So the only way to extend the nozzle into the furnce would be to increase the oil feed pipe size from 1/8" to 1/4" ID.
The problem with that was that the pipe fittings would be that much larger and would block more airflow through the outer blower pipe.
I decided to see if I could eliminate any 1/4" pipe fittings but still use a 1/4" iron pipe. The first thing was to check to see if I could internally thread a 1/4" iron pipe to take the 1/8" pipe plug that is used as an oil nozzle in the original Kwiky. I suspected this could be done but had never tried to internally thread one pipe size to fit another. If it wasn't possible, I decided I'd make a press in plug for the pipe, and drill and tap that to fit the nozzle plug.
Internal threads would eliminate the need for an air inhibiting 1/4" pipe coupler (and 1/4" plug nozzle).
I also decided to silver braze the 1/4" pipe to the existing 1/8" oil tee. This would eliminate a 1/4" to 1/8" reducer.
Here is a picture of the setup for brazing these two.
Oh, it also turned out that, yes, the 1/4" iron pipe could be successfully threaded internally to take the pipe plug nozzle -- shown here on top:
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