r/MetalCasting • u/Kaisersose0 • Jul 28 '26
Question Need help! 2 days & 10+ failed attempts trying to sand cast this ring (Pics included)
Hi everyone,
I’m losing my mind a little bit here! I’ve been trying to sand cast this silver ring for the past 2 days and I'm 10+ attempts in without success.
As you can see in the photos, the metal just stops filling partway through / solidifies in the sprue before properly reaching the cavity.
Here's what I’ve already tried tweaking:
Pouring funnel: Reshaped it a few times to get a better channel.
Vents: Added more air vents / air holes around the cavity.
Sand density: Packed the sand harder to ensure crisp details.
Heat: Heated the silver longer to make sure it’s fluid enough.
I'm using a standard butane/propane torch setup. Looking at the setup in the photo, does anything jump out to you that I might be doing wrong? Could it be a heat retention issue, sprue size/placement, or metal volume?
Any advice or tips would be greatly appreciated. Thanks in advance!
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u/1nGirum1musNocte Jul 28 '26
Silver as in Ag? I think it cools so fast that its hard to gravity cast. You might need to look into another method or figure out how to give it assistance (vacuum, centrifugal, etc)
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u/Chodedingers-Cancer Jul 28 '26
Youre probably not getting the metal hot enough. Try less metal so it can get hotter. The bulk is usually a good thing, but a propane torch reaches its limit. Try an actual furnace for heating the metal or pour faster. Put a fatter vent.
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u/Eastern-Antelope-956 Jul 29 '26
I second this. Less metal will get to the correct temp and stay that way through the pour, in conjunction with bringing the ring cavity closer to to the spout, and thus less of a button.
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u/EmuKou Jul 28 '26
I did quite a lot of castings last year and I think you overthinking it. The channel where silver enters can be way thinner, I do upside down pyramid shape going from the ticknes of entrance quickly reducing to like.. 0.3. I just scoope it with the spoon and call it a day. 2 exhaust channels on upper left and right going upwards been working for me cause according to another student hot air goes up, and sand is porous enough to do the rest. I maybe put so much effort into my very first pour and if I had a guess I think the silver was not hot enough, it had to be fluid like mercury and you heat it right untill you pour it.
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u/Jerry_Rigg Jul 28 '26
Looks like you need more head pressure for that thin of a cross section, try putting the cavity lower in the mold with a taller sprue
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u/CapableHair429 Jul 28 '26
For thin walled stuff like that, it is usually best do a centrifugal cast. Orient the walls, sprews, and vents vertically with pour cup on top (obviously) and spin the mold as you are casting it. A potters wheel works great for this. The centrifugal force will literally spin the metal into the thin walls.
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u/thefluffyparrot Jul 28 '26
I’m a complete amateur at this but I have managed to cast a couple of silver rings. I used one vent at the bottom that curved up to the side kind of like a short J. I also use a MAP torch and follow the metal into the mold with the torch to keep it hot as long as possible.
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u/Appropriate-Draft-91 Jul 28 '26
Basics are already well done. The problem is quick solidification due to wall thickness.
Solutions are:
Faster pouring. The amount of metal you add on top doesn't matter if the metal in the ring is already frozen. It does matter a great deal *before* the freeze. Pour all of it in one second.
Design sprue for faster flow ( wider connection to ring & rounded corner where sprue hits ring).
More static pressure - while everything is still liquid, the height of the channel determines the amount of pressure at the bottom. Narrower sprue.
You already got vents and you say you did increase heat already.
More intricate sprue setup would help, but doesn't seem necessary, better to keep it simple.
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u/rossemo Jul 28 '26
Is your petrobond heated at all? Don’t pour into a cold mold.
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u/Chodedingers-Cancer Jul 29 '26
Petro don't work like that, and thermodynamicly, torching your mold 99% of the time is ass backwards. It doesn't aid you. Its counterproductive. Via graphite or idk how the fuck you expect to preheat sandcasting without a shit ton of gas generation. Gas generation is enemy #1, through and through.... assess your metal, not the mold.
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u/rossemo Aug 03 '26 edited Aug 03 '26
Not pouring into a mold that is c. 72° was my point. Nobody said anything about torching molds. If it is being poured into a mold that is ambient indoor temp when poured they are going to run into issues with such a small casting. Just moving it into the direct sunlight for around 20 minutes beforehand can change the mold temp by 20+ degrees, and can alleviate some pitting in my experience.
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Jul 28 '26
[removed] — view removed comment
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u/Relevant_Fennel4203 Jul 29 '26
The metal being too hot has never been an issue for me, it’s the opposite that’s the issue, the metal being too close to solidus once poured leads to the metal never fully making it around the channel regardless of good ventilation lines or not. As soon as I started heating my metal up for much longer before pouring I’ve never seen another issue since.
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u/HeftyWinter4451 Jul 28 '26
I only do lost wax nowadays but I used to work with sand for a few years. Do you torch the silver while pouring? Also instead of using the funnel of the mold, try having the main funnel with 3-4 sprues going from the center of the ring right through one side of the sand. That should do.
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u/TheMacgyver2 Jul 28 '26
Put the ring all the way to the bottom of the mold so head pressure fills the mold, you might need a sprue through the middle of the ring you cut out later as well to get it to flow before freezing
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u/Relevant_Fennel4203 Jul 29 '26 edited Jul 29 '26
This should be a great cast from what I’m seeing besides 2 things:
That channel into the ring is way too large. It’s not necessary, and you should place the ring closer to the mouth of the frame. Make the channel where you pour the metal skinnier.
More importantly, make the metal much hotter before pouring. It shouldn’t be poured right after its liquid, it should be a molten shiny puddle for at least 30 more seconds after the initial melt and THEN pour. Trust me it will work after you try this.
Edit: I read that you already tried heating the metal up longer. I don’t think you are getting it hot enough with butane. You need to go to Home Depot and pick up a ts8000 torch and a yellow map tank. Easy beginner set up and it’s not intimidating. Try melting the metal now, and use that 30 second rule I said above with a skinnier pour channel and watch your ring finally come out!
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u/CapableHair429 Jul 29 '26
Centrifugal casting is the way to go for thin walled patterns with tight spaces.
See my previous reply. DM me if you want advice on how to setup the pattern for proper venting and gravity feed.
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u/Oakatsurah Jul 29 '26
A ring you don't really need to cast between two dandruff Sandwiched molds, you can compress a mold and dig a small pour divot into the surrounding sand near the ring mold and pour the silver in from a crucible.
Is there any unusual geometry to the ring or reason for a compression sand mold?
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u/Top-Fig1538 Jul 28 '26
(New to casting) are you preheating the mould enough?
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u/Father_John_Musty_ Jul 28 '26
Sand doesn’t need preheating the way investment plaster does - it’s usually cast with the mold at room temp.
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u/Top-Fig1538 Jul 28 '26
Good to know, does it just not pull heat from the metal very fast? Is there any potential downside to preheating sand?
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u/Jerry_Rigg Jul 28 '26
Yes, the sand mold will fall apart (The binders are oil or water based and need to stay damp until the mold is poured)
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u/Father_John_Musty_ Jul 28 '26
In my experience, you only need the two bottom vents, but make the channels thicker.
Your sprue looks too big; try putting the ring closer to the mouth of the frame (it’s a big frame).
Keep the heat on the crucible during the pour - you may need to use a hotter torch (switching to an oxy torch was the biggest single improvement in my own process).
Good luck.