After building the Gingery Furnace, it was finally time to start making stuff out of metal!
11/20/2000 – An 8×10 flask
11/21/2000 – Preparing green sand
I made green sand with play sand and fire clay. Play sand is
too coarse a mesh for molding, I’ll have to look for a finer mesh sand. But it works well enough to start with, and that’s all I have been able to find so far, at the local Home Base.
The important thing about green sand seems to be to not add too
much water. Just enough to give the mix some cohesion, and no more. It’s very easy to overwater it, and it will ruin the castings.
11/24/2000 – First Melt
For my first melt, I didn’t try anything fancy. Just melting some
aluminium and pouring it in an open mold.
|I started the charcoal with the air on fairly low, and that went much better than during the curing.|
Then put in some aluminium scrap in my “crucible” (a coffee can), put the lid on, and started the blast.
The furnace heats up very fast. The can almost immediately started glowing red, and I had to reduce the air to keep it from burning a hole through the bottom.
The furnace melts aluminium very easily. I used some window frames picked up at the scrap yard. You get some amount of slag, but not excessive.
|Inspection of my first blob of aluminium revealed plenty of steam bubbles. My sand was far too wet, and I obviously packed way too hard, almost as hard as the lining. I’ll have to try again.|
11/26/2000 – First Part
For my next project, I decided to try and make a very simple casting from the Gingery lathe project, and (since there was plenty of room in the flask) a small replacement part for my drill press.
11/26/2000 – Casting is HARD
Also, further reading of the book showed that I made no fewer than 4 mistakes: I left the pattern with sharp edges, when they should have been sanded smoother; I also left the pattern in unfinished wood, which heightened its adherence to the sand and made the pattern removal difficult; I did not vent the mold enough; And finally I put the sprue smack in the center of the pattern, instead of to the side with a cutout to the pattern, which caused a lot of shrinkage.
The book also mentions tapping the pattern from below with the venting wire, which is a nice way to both vent the mold and help extract the pattern.