Ideas needed for alloying project

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  • Last Post 26 May 2013
vmwilson posted this 19 March 2013

18 lbs lead BHN 8  126,000 grains Super Hard Ingot  10,500 antimony     24,500 lead 7.4 oz tin   3220 grains     ____ TOTAL WEIGHT  164,2220 grains

    6.4% antimony     1.9% tin     91.7% lead

From Roto Metals formula 8 +.6 +5.9 =   14.5 BHN

Plan is to make four batches and then feed the pot with 4@ l lb. ingots at a time when I actually cast the bullets for my 9mm carry gun. Hope to get the mix in the 14-15 BHN range.

What I need is input on tips for smelting the mix.  Have a 40-45 lb. pot with a LP gas furnace and own a good thermometer.  Have melted a lot of lead with that setup over the years. 

Will a good stirring of the mix get the 3 elements blended sufficiently or is something additional required?  Plan on adding the “warm” ingot of Super Hard and the tin after the lead is up in the 700 degree range.

I figure I should get around 90+ ingots of around 14 BHN.  Anyone have any input on what I'm doing and any corrections needed?

Oh, and what's the best way to cut the tin ingot into smaller weights?

Mike

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onondaga posted this 19 March 2013

http://www.castbulletassoc.org/view_user.php?id=974>vmwilson:

One procedure that really helps to alloy bullet metals well is to melt the heaviest, highest melting temperature metal first by itself. when completely fluid then add, melt and flux each additional metal progressively to the lightest, lowest melting temperature metals.. In your case first melt the BHN-8 lead, flux, then add the super hard, melt, flux and last add the tin, melt and flux.

If you do this out of order you can get an oatmeal looking higher temperature mush floating on top that will be hard to get into alloy unless you use extreme temperatures that will oxidize a lot of tin that you can only return to alloy with a specific reduction fluxing method and fire.

Understand that if you mistakenly melted the tin first, you would have to superheat it to be hot enough to melt the lead into it. That is a mess, avoid that. the same will happen if you melt the superhard first and try to get the BHN-8 into it. Start with the BHN-8 and melt it first. Definitely don't just throw everything in the pot and crank it up. you would oxidize a lot of tin doing that and require a lot of heat to get the mix to melt and then reduction fluxing with fire to get the tin oxide back into alloy.

If you don't thoroughly understand what reduction fluxing with fire is and don't do it correctly, again you will have a mess with oxidized tin that looks like dross but is not and oatmeal floating on top that you may not be able to alloy without extreme heat and reduction fluxing..

The most common mistake is skimming the top and tossing a lot of tin out because it wasn't hot enough to flux in the first place. Tin oxide is a fine dust on top of a melt, not a heavy glop. If you have a heavy glop, you have not gotten your melt hot enough to flux....don't throw the glop out---that will ruin your formula. Melt it and flux it correctly till there is just dust. Even most of the dust can be reduction fluxed back into alloy.

Your 7.4 oz of tin should be added last. If you have to cut it to pieces, I find using an axe held in place and struck with a sledge hammer over a stump to work fine.

Gary

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delmarskid1 posted this 20 March 2013

I did it just as Gary described. I should say that I didn't get it right the first time and he's right about the mush on top. I got this glop to melt in with a propane bottle torch.

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vmwilson posted this 20 March 2013

Figured somebody had done this before and would have some tips for me.  Thank you fellows!

 

 

Mike

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onondaga posted this 20 March 2013

http://www.castbulletassoc.org/view_user.php?id=974>vmwilson:

Your 700 degrees is a good temperature. Just remember that Tin in the alloy oxidizes instantly at 800 degrees when exposed to air, so stay away from excessive heat when making alloy or casting.

Gary

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Lee Wiggins posted this 20 March 2013

As to “Cutting the tin ingot into pieces” Melt it and pour it on a clean dry concrete floor. Pick up the metal sheet and cut it up with sissors. I do this with WW and Lino to get small pieces to add to my scale along with ingots to get exact weights of each for my alloys.

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vmwilson posted this 11 April 2013

Mixed my metals 3-24-13 and measured 15 BHN today (4-11-13). My lead initially was 7 BHN and I weighed the ingots in ounces before settling on this blend.

1398 oz. lead - 31 oz tin - 302 oz. Rotometals Super Hard

FWIW

Mike

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delmarskid1 posted this 12 April 2013

That is a nice sounding alloy. I'll bet it was easy wasn't it?

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vmwilson posted this 14 April 2013

delmarskid1 wrote: That is a nice sounding alloy. I'll bet it was easy wasn't it? Actually had a nice time doing it.  Wanted it for my LC9 mainly but have probably 10K of bullets lubed and sized for it already so unless I can't stand it some rainy day I likely won't actually cast anything with it for the time being. 

Mike

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Tuner posted this 26 May 2013

Onondaga: Let me make sure I have the info in your post #2 above correct.
1. If I am alloying WW and 2% tin I should melt the WW first then add the tin. 2. If I want to make a softer alloy for hollow points and add some lead I should melt the lead first, then add the WW, and then add the tin. BTW, if it makes any difference the tin I am using is 95/5, Tin/Antimony.

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onondaga posted this 26 May 2013

http://www.castbulletassoc.org/view_user.php?id=5118>Tuner:

Yes, you are completely correct.

Melt the higher temp stuff first, then add each lower melt metal in order by next lower melt temp order....you got it right.

Gary

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Tuner posted this 26 May 2013

Onondaga:
Thank you, when it comes to the Pb's, Sb's, Sn's, etc. I can be a bit of a slow learner. As luck would have it I have been doing the WW and tin in the proper sequence probably as a result of the quantities of each. I do want to try a more malleable mix for some hollow points and would have never thought of starting with the pure lead first. Your post and my reading of your post was most timely.

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