An alloying session today

Alloys and alloying your own
Rasper
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An alloying session today

Post by Rasper »

I melted three #8 pots of copper wire today, added some silicon and manganese, and poured ingots. I need Everdur to cast "The New Girl" and I don't like alloying and then pouring directly into an investment; I prefer to see what I have first. There is about 50 pounds here.

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I poured this too. I'll break it out tomorrow.

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It's a piece for the exhibit we have here every February. There are usually about twelve participating artists, and each of us gives a piece of our work for the raffle. The money from the raffle goes to cover the expenses. This is the raffle piece.

Richard
dallen
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Re: An alloying session today

Post by dallen »

they ingots look pretty good, can't say about the pour its hiding in plaster
David and Charlie aka the shop monster

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Rasper
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Re: An alloying session today

Post by Rasper »

can't say about the pour its hiding in plaster
It busted itself out today.

Image
dallen
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Re: An alloying session today

Post by dallen »

nice looking cup. I tried to mold one up in sand one time, never could get the sand to work right around the handle, so I gave it up.
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
F.C.
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Re: An alloying session today

Post by F.C. »

One of the most challenging feats in the Navy foundry school is to use sand (only) to pack and pour a cup/saucer/spoon (all together in place as if setting on a table ready to use). It wasn't a requirement but those who could figure out how to do it and accomplish it were considered masters of the art of mold making. I know "how" it's done but not had the desire (yet) to do it, myself. Suffice to say it involves sand cores that you'd make using a mix of dry (mixed w/bentonite) sand and 3% linseed oil which you would pack as the necessary cores then bake like cookies to a light caramel brown which would harden them for use and resist damage from packing the bulk of remaining necessary sand for the overall mold. Chills inserted into the mold (adjacent to the cup and saucer) at strategic points to help control cooling and give the cast a more sheen luster than would otherwise occur in the cast and help in cleaning it up (polish) to a mirror luster. The more complete, without imperfections, the more beautiful finish, the greater one's skills would be demonstrated. The end product is supposed to appear as a compiled set of cup, saucer & spoon all in the same metal, without welds or glue utilized.

I know full well (though unproven as yet) I can do it with plaster as a mold medium (because I've made once a 15 piece mold to cast a 3" rose, stem, leaves and thorns as one cast in silver years ago in college). But the idea to do it in sand still has a mental draw to me to step up to one of these days. LOL...
Rasper
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Re: An alloying session today

Post by Rasper »

Chills inserted into the mold (adjacent to the cup and saucer) at strategic points to help control cooling and give the cast a more sheen luster than would otherwise occur in the cast and help in cleaning it up (polish) to a mirror luster.
Can you say more about that?

I am never satisfied with the surface of my castings.I get tiny potatoes, which are not much of a problem, but I also get tiny pits. And the surface is generally rough, definitely not a sheen lustre. I use brush-on coats of investment that contain enough extremely fine particles to give a good finish. I have learned not to pour too hot, and to let the casting cool completely before breaking it out.

Am I dreaming the impossible?

Richard
F.C.
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Re: An alloying session today

Post by F.C. »

I was referring to sand molds, Richard. Investment molds (requiring burn out and pouring while hot) is totally different. Sand molds are somewhat cold and porous when pouring metal in. As long as you have a uniform (near as possible) thickness to the overall item being cast you get a uniform finish. Chills (nuts, bolts, bits of steel or steel plate, etc.) placed inside the sand adjacent to the thick portions of the cast will aid in solidifying the thick cast areas first while the rest (thinner areas) are still molten and drawing from the pour cup as they chill on their own. These chills should be stored in a deep freezer to keep them cold as they can get before use. If the piece is uniform in thickness throughout (such as a table trivot) you can also aid the overall freeze of metal by use of chills which will reduce the amount sand detail the metal receives as it sits molten for a bit capturing the mold surfaces it's within. I'd also recommend adding to your sand (in doing sand molds) 3% corn flour to your overall mix. This will cause a subtle light flaring in the sand mold finish that creates a nice layer of carbon fines that will damn near eliminate surface scale on a bronze cast, and make aluminum casts equally as shiny. The flaring is not eruptive in any way, but it'll make the sand mold's interior layering of sand much blacker with carbon fines.

In plaster molds, you already have the wax carbon fines from the burnout inside the mold.
Rasper
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Re: An alloying session today

Post by Rasper »

My little pits seem to be from bits of trash or whatever rather than shrinkage or gas. I have begun using a glass cover which is great at collecting up all of the trash on the surface of the melt, and I am careful to eliminate sharp pointed edges of investment that can break off.

I am thinking about trying a higher percentage of plaster in my initial brush-on coats. Perhaps that will make more solid the investment that contacts the casting. I currently use about 2 parts plaster to 3 parts other stuff (by volume) for the brush-on coats.

Richard
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Re: An alloying session today

Post by Rasper »

The coffee cup is getting some class.

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Now all that remains is to put some hot chocolate in it. I'm figuring some tinted plaster for the chocolate and a plaster saturated cotton ball for the dollop of whipped cream.

Richard
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Jammer
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Re: An alloying session today

Post by Jammer »

That doesn't sound very appetizing. How big is the cup? Kind of hard to tell with you, it may be 3 feet tall. :D
quando omni flunkus moritati 8-)
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