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Home Metal Casting
and Machining
Page 3
WARNING! Activities on these pages about foundry work are very dangerous. The chances of having a fire, causing injuries, or even dying are very good if you are not careful. I am not a professional foundryman, and will not attempt to disclose all hazards. If you choose to try this hobby, every precaution must be taken to be safe.
Metal Casting Tips for Gingery Machines
The Gingery lathe bed, base castings
and mill base castings are hollow underneath. The patterns are built this
way in the book but I chose a different route. If the patterns are built
like the book says, the sand in the hollow part often does not want to release
and stay with the pattern. So I made these parts solid and made little core
molds separate shown below.
I
made these core molds out of cheap press board and super glue. I formed
them into strips cut to make the inside the dimension like the cores are in the
books. The top and bottom are open. Coat the inside with parting
dust, ram molding sand into it, push out the core and place it in the mold
cavity where you want it. I think this way is easier than forming your
pattern hollow and trying to get the cores to release from the patterns.
Instead of making the baked sand core
for the tailstock, I took a piece of cold rolled steel the same width of the
core, brushed some high temp never seize all over it and wrapped some
aluminum foil around it to maybe help keep the never seize from washing off with
the molten metal. Once the casting cooled, I pounded out the core with a
hammer and it came out well.
I am pretty sure I get the concept of
scraping, but after filing and scraping on my lathe bed for a while. I
didn't seem to be getting anywhere. I suspect that sometimes internal
stresses in the casting may put some twist on the casting that gets worse as you
file away metal in areas. So instead of scraping more I smeared JB Weld on
the top of the lathe bed and put it face down on my flat surface (a piece of
scrap granite countertop) with some wax paper in between the two to keep them
from sticking together. The pic above shows what I did but what you see is
the bottom of my lathe bed pattern used for demo since I didn't take a picture
at the time. (Notice how the pattern is solid at the bottom. Sand
cores were placed in the molding sand void were they were supposed to be in the
pattern when casting the lathe bed and bases).
For the shim stock called out in the book, I just used aluminum foil.
If I ever cast the lathe cross slide and compound slide again, I would probably make them flat and bolt the end on like the one on the Gingery Mill.
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