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I Forge Iron

Melting Silicon Bronze Rods (Bad or Good idea?)


intrex

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Hey Everyone, 

My brother wants me to forge a bronze bracelet for his 10 year anniversary.  Unfortunately he told me this today and his anniversary is Monday. After checking with all local suppliers and hardware stores the only way I find any silicon bronze is by using pure bronze brazing/welding rods.   The problem is that they are only 3/32 in diameter and I really need about 1/4 square bar to forge what he wants.  

I know that I could try to wrap the rods together and forge fuse them together but I am worried that this is going to be a tricky process.  I have done something similar to this with silver wire before.

The other option I can think of is to weld up a mild steel box that is roughly the volume of the stock size I want.  Put the box into the forge to heat it up to red then start slowly adding in the rods.  I may end up doing the heating with the oxy torch while adding the rods.  Has anyone on here attempted to do something like this? I obviously don't have a proper foundry setup in the shop. 

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I melted my copper wire that way. I made a "crucible" out of mild steel, then made a mild steel mold. One thing that I was told, put borax in the crucible to help drive out impurities. I scraped the "junk" off the top before my pour. Then the mold, light a candle and coat the mold in the soot from the candle. It helps it from sticking and will come out easier. Hope that helps some. 

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Bronze and copper actually "forge" weld quite easily. However if you have a brazing torch melting them together is really easy.

Angle iron makes an easy mold, dust it with talcum powder as the release agent or "smoke it with soot  from the acet torch and no oxy. One good thing about angle iron is, if the ingot gets stuck just grind through the angle and you can beat them apart by laying the angle iron (ground off) angle up on a solid surface and smack it with a hammer. So long as you didn't get the mold high red hot the ingot won't be brazed to it and it'll just come apart with some blacksmitherly persuasion.

Carved fire brick works well but dust it first so loose particles don't end up in the billet. 

If you melt the rod in a crucible you can simply make a trench in dry (powder) clay, plaster of paris, etc. and gently pour into it.

Lots of ways to do this just be CAREFUL molten metal is inherently dangerous and a steam explosion can maim or cripple you. You'll also want to use good ventilation and respirator, just because the package says what's in it doesn't mean any bronze alloy doesn't contain some zinc. Good PPE, careful handling and good ventilation.

Frosty The Lucky.

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Thanks for all of the info frosty.  

I am going to be doing this outside and wearing a respirator.  We are going to be super careful about moisture as well.  After all of the feedback and thinking about this in detail the plan is going to be to carve out the shape I want in fire brick.  Cut the rods up and place them in the mold and throw the whole thing in the forge.  Then I can just turn on the forge until they melt and let it cool hard in the forge before moving.  That way I avoid having to deal with molten metal with improper tools and lack of a real crucible.

I will be also be purchasing a crucible this weekend in case I run into this situation again :)

My bro will take pictures so you guy scan see how this goes. 

 

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It's probably going to take quite a while to heat the brick up and the bronze might absorb bad things. I think sprinkling some borax on the melt will take care of that. I wish I remembered what we used to carve molds from in high school.

It'll work fine, don't forget the pics please., we LOVE pics. :)

Frosty The Lucky.

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  • 2 weeks later...

Hey Everyone, 

Thanks for all of the pointers.  This worked out fine and we completely smelted and forged the bracelet in one night which I thought was pretty impressive considering we started at 6pm and took a break for dinner.  

The first try without borax was a complete failure for smelting.  The picture below will show all of the crud.  After adding borax and putting it back in the forge everything melted like butter.  Forging bronze without overheating it is pretty tricky.  I ruined the first run.  Thankfully I smelted enough bronze for two tries and the second one turned out just fine. 

 

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