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I was packing my sand molds way too tight for years

A guy from the old Johnson Foundry in Toledo showed me his method last month. He just presses firm but doesn't ram it down hard. I tried it on a set of six small gear blanks and the surface finish was way better, with less gas holes. How do you all judge the right packing pressure?
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3 Comments
grant.zara
grant.zara22h ago
What's your trick for knowing when to stop pressing?
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cameronjenkins
Listen for the hiss to fade out.
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wesley385
wesley38522h ago
A podcast said to stop when the grounds look like wet sand. It's a simple visual cue that works better than timing for me. That tip changed my whole routine.
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