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Had a talk with an old sand molder that made me rethink my whole approach
I was at a shop up in Cleveland last week picking up some cores and got to chatting with this guy who's been running green sand for like 40 years. He saw me struggling with a big casting that kept coming out with gas holes and just laughed. Said I was rushing my compaction and not giving the sand enough time to breathe before the pour. He showed me his method where he takes an extra 2 minutes per mold to vent the deep pockets with a wire. I figured I was saving time by skipping that step but now I'm thinking about the 50 bucks of iron I wasted on bad castings last month alone. Has anyone else had an old timer call out something simple that you were overcomplicating?
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caleb_bell53mo ago
Wait, are you sure he was running green sand for 40 years? Because venting deep pockets with a wire is usually for no-bake or oil sand molds. Green sand already has natural permeability from the clay and water. If you poke wires through it, you can actually seal off the vent paths and make gas holes worse. I had a similar thing happen with a pump housing last year. Turned out I was overworking my muller and collapsing all the pore space. Maybe check your moisture levels and mulling time before you start stabbing holes in everything.
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