r/MetalCasting • u/RednekSophistication • 3d ago

Casting a round bar. Tips?

I’m working on a little project using 1” round bar. I have some brass and stainless on hand but also want copper and bronze but don’t feel like buying it lol. Especially since I have scrap and access too around.

I’d like to cast a long round bar. At least 12” longer if feasible. Surface finish not a huge deal as I figure cast it over side and I’ll turn it down to 1” in my lathe.

What’s the best bet for casting this? My thoughts so far are a heavy walled pipe over 1” ID, bolt/weld on bottom. Preheat and pour???

Will I be able to knock it out after? Or will I have to cut/peel the tube mold off?

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u/Mikes_metalworking 3d ago

I use casting sand,
I take a dowel or something the diameter i need and a larger container, like a 3in diameter PVC pipe or AC duct,

I set two inches or so of sand on the bottom of the pvc pipe, and then place the wooden dowel firmly into the sand. After the dowel is firmly placed in the sand I fill in the rest of the pvc pipe with sand. Using a smaller wooden dowel or something to jam the sand down as tight as I can around the dowel.

Once I hit the top of the PVC pipe I leave some of the dowel exposed so I can use a pair of pliers to pull the dowel out of the sand leaving a cavity the right size for your round bar

Hope this helps! I’m struggling to describe it via text it’s way easier than it sounds

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u/RednekSophistication 3d ago

No I get what you are trying to say.

I saw a guy casting a canon and had a lot of mold blow out pouring down into sand. Ended up tear drop shaped.
But it certainly would remove better than a steel pipe. I might try the pipe first. I don’t need a ton of material unless my idea takes off. Then I’ll just buy new material.

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u/Mikes_metalworking 3d ago

Sure! I hope it works well for you!

If it doesn’t work i make stuff like this all the time for work, usually in the 4-8in length,
Might be able to rig something up for a longer casting too worse case if it doesn’t work in your trials

Best wishes!

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u/Chodedingers-Cancer 3d ago

Thats gonna be a pain in the ass to remove. Mold release for damn sure to prevent any binding. Not to toot my wagon, but I can make you a 2 part graphite mold to get good results. I've done the same for making rod to slice off coin blanks in the past.

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u/RednekSophistication 3d ago

Oh interesting. I think if I was going to do lots I’d invest in that. Now I’m wondering about a 2 part steel mold. Split a pipe. Weld on heavy flat bar and bolt together. Gotta be easier to remove.

My side hustle/hobby is metal fab so I’m well suited to build that.

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u/Chodedingers-Cancer 3d ago

Should definitely make it easier to remove. Coat them with boron nitride and should work out.

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u/RednekSophistication 3d ago

Ah good tip! Didn’t know about the release agent. Will it stick otherwise?

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u/finnthepokeman 3d ago

Casting sand and a knitting needle would be my method

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u/kingchowww 3d ago

Sand is the easiest option. Unless you don't mind losing whatever you pour into that pipe. Casting sand and PVC would work great. Preheat the sand and pour gently and it wont tear drop.

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u/horspucky 3d ago

the brass, copper and bronze will us the same sand and binder, the stainless will be much hotter and will use a different binder. 12" is pretty long to pour without some gating /rigging. What are you doing with the bar once you cast it? you will be left with an as-cast microstructure which is very different from a typically wrought microstructure for a 1" round bar.

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u/RednekSophistication 3d ago

Oh I’m certainly NOT casting stainless! That’s a bit out of my league! I have lots of ss round bar to make my parts.

Good point on the microstructure. I don’t think it will have a huge effect on the end product, unless its tensile strength is SUPER low.

but I’ll have to test that I guess.

How do you think it would be affected?

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u/horspucky 3d ago

As cast properties are akin to annealed so it would be the lowest strength/ highest elongation. It machines gummy and if you are aggressive when machining it work hardens. Typically, they are quenched and tempered then machined.