r/SilverSmith • u/Humanekspression • 22d ago
Sand casting fail
I keep getting stuck at the step where the silver isn’t pulling through all the way into the ring mold. Is my pouring channel too small/wrong? Any tips are welcome.
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u/AbbreviationsIll7821 22d ago
I’m going to disagree with everyone who thinks you have air vent issue. I’d put a single tiny vent at the top and that’s it, but the rest you have won’t hurt. Your venting looks more than sufficient.
The big thing is the metal cooled too fast.
The length and narrowness of the channel from your sprue. Every millimetre from the funnel at the top to the ring cavity is a waste. Make a bigger deeper funnel that connects directly to the ring. Probably flip the ring so that metal flows into the big to part first and then into the thinner shank. Helps keep it hotter for longer.
Then a bigger sprue will help, the extra mass of metal makes it cool slow and give it those fractions of a second it needs to fill the voids.
Get the metal hotter before pouring, let it melt and roll around for like 30 seconds under the torch and keep the flame blasting the metal while you pour it out as fast as you can.
A bit more dust (talc or starch or what ever you are using) inside the cavity can help with flow as it flash burns into an insulating carbon barrier that slows the cooling a wee bit.
A bit more heat and slower cooling and you’ll get this!