Making bell metal bronze for bolsters

M

MoSmith

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May 28, 2017
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I've been using brass for bolsters on my knives and it works well but I don't care for the looks of it that much and thought I'd try original bronze instead. I'm not really interested in most of the other copper alloys such as aluminum bronze, phosphor bronze, etc. I'm going to try making the traditional bronze tomorrow, 78% Cu and 22% Sn and see what I can do with it. Does anyone else do this or have any idea of the pros and cons of this material as bolsters?
 
I do it quite a bit. Be carfule with the tin. A little tin goes a LONG ways. And you can add to much to where the bronze becomes brittle. Also when making your copper ingots watch out for desolved oxygen in the copper. This happens normaly but gets even worse if you over heat the copper. As tgecopper cools it try’s to let go of the gas and makes big voids and bubbles. Once you get your copper melted you want to clean all the dross off the top. Use alittle flux to sheald the top of the copper from the atmosphere gasses. Copper melts right at 2000° so I normaly run the forge at 2200° and not a deg over. Pull your crucible out of the forge and scrape the surface of the copper clean with a little scoop. Then let it cool just alittle. You dont want to cast it while it as 2200°. The trick is to wait till it’s right above the melting point. The quickly pore it into your ingot mold. Once it’s hardened up quench the ingot in water and that will clean the copper and blow off any flux that came out. Now you measure out your ingredients and get that sorted. You then heat your crucible back up. Make sure it’s clean and does not have any copper or gunk in it from the copper melt. Then put your clean copper in the crucible and get it melted. Once it’s liquid I add a tiny pinch of flux and add the tin. Use a graphite rod to mix it in and skim off any gunk that floats up. Then drop the forge temp to around 2000° and put it the crucible back in. Once it’s at temp you pore the bronze into your ingot mold. If your using steel for a mold becatfule bevaus if you over heat the bronze it will solder it’s self to the steel making it a pain in the ass to get the ingot free from the mold.
 
JTknives said:
I do it quite a bit. Be carfule with the tin. A little tin goes a LONG ways. And you can add to much to where the bronze becomes brittle. Also when making your copper ingots watch out for desolved oxygen in the copper. This happens normaly but gets even worse if you over heat the copper. As tgecopper cools it try’s to let go of the gas and makes big voids and bubbles. Once you get your copper melted you want to clean all the dross off the top. Use alittle flux to sheald the top of the copper from the atmosphere gasses. Copper melts right at 2000° so I normaly run the forge at 2200° and not a deg over. Pull your crucible out of the forge and scrape the surface of the copper clean with a little scoop. Then let it cool just alittle. You dont want to cast it while it as 2200°. The trick is to wait till it’s right above the melting point. The quickly pore it into your ingot mold. Once it’s hardened up quench the ingot in water and that will clean the copper and blow off any flux that came out. Now you measure out your ingredients and get that sorted. You then heat your crucible back up. Make sure it’s clean and does not have any copper or gunk in it from the copper melt. Then put your clean copper in the crucible and get it melted. Once it’s liquid I add a tiny pinch of flux and add the tin. Use a graphite rod to mix it in and skim off any gunk that floats up. Then drop the forge temp to around 2000° and put it the crucible back in. Once it’s at temp you pore the bronze into your ingot mold. If your using steel for a mold becatfule bevaus if you over heat the bronze it will solder it’s self to the steel making it a pain in the ass to get the ingot free from the mold.
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Thank you! I haven't done any of this kind of work before and can't tell you how much I appreciate the practical advice. So far, I haven't found any useful procedures for making this. Most sources just imply that you mix some tin and copper and melt it without mentioning any of the "gotchas" that are gonna come up in the process. Thank you again.
 
I think you have too much tin in your alloy. "Historic" bronze was 88/12% mix, "Classic" bronze was 90/10%. Classic bronze was used for weapons. Bell metal bronze is too hard and brittle to work and make anything but cast fittings.

I used to make it and used the same basic methods JT gave, but used an oven.
Only additional advice is I used a boric acid borax blend as flux. about 1/4 cup boric acid to a cup of anhydrous borax. Sometimes I added an ounce or so of finely powdered charcoal to consume oxygen.

Nowadays, I just buy good bronze on ebay or from a metals supplier.
 
I have seen some data on swords that was measured at 13% tin. Tin is powerful stuff and a little goes along way. Silicon is even more powerful, a little pinch of that and your good to go. All the bronze I have been making is of the silacon variety. I use alittle tin in replacement of the manganese. My stuff comes out great but it does have a warmer color then 655 sibronze. But man can you work harden it to a rather impressive degree.

If you need anymore help let me know I would be glad to assist.
 
Stacy E. Apelt - Bladesmith said:
I think you have too much tin in your alloy. "Historic" bronze was 88/12% mix, "Classic" bronze was 90/10%. Classic bronze was used for weapons. Bell metal bronze is too hard and brittle to work and make anything but cast fittings.

I used to make it and used the same basic methods JT gave, but used an oven.
Only additional advice is I used a boric acid borax blend as flux. about 1/4 cup boric acid to a cup of anhydrous borax. Sometimes I added an ounce or so of finely powdered charcoal to consume oxygen.

Nowadays, I just buy good bronze on ebay or from a metals supplier.
Click to expand...
Thank you. Maybe I'll have to back off on the bell metal and try the weapons bronze instead. Strange how a 2% change in the tin component makes such a difference. As JTknives said, tin seems to be some potent stuff.
 
JTknives said:
Here is a real short video I put togather of casting up an ingot for Salem.

Click to expand...
I loved the video, thanks for that. I need to make something a bit better for a mold as well. The more I learn the more work there is to do! *S*
Thanks again, I'll let you know how this turns out.
 
Why not use waterworks bronze? It looks good, is easily machinable, and readily available. Just go to a waterworks supply house and buy some corp stops, curb stops, angle meter stops. Just make sure you get 85% Cu, 5% Tn, 5% Z, and 5% Pb.
 
tim37a said:
Why not use waterworks bronze? It looks good, is easily machinable, and readily available. Just go to a waterworks supply house and buy some corp stops, curb stops, angle meter stops. Just make sure you get 85% Cu, 5% Tn, 5% Z, and 5% Pb.
Click to expand...
That would probably be a LOT easier. *S* I'm making a knife for a friend of mine who has a transplanted kidney. Something I didn't know was that lead is VERY bad for a person's kidneys so I'm trying to avoid that.
Thanks for the idea though.
 
The lead tends to make a brittle alloy .Si bronze is easy to find ,good color. BTW many blades in the bronze age were work hardened to thin the edge and harden them.
 
I would stay away from bronze with lead in it. I’m not a metallurgist but the reading I have done says that the lead does not alloy with the bronze. It’s kinda suspended around the alloy. This is why it machines so nice. This makes me think that it can come out a lot easier then if it actualy became part of the alloy.
 
Thanks to you all. I've been trying to avoid zinc as that stuff just isn't good for you when it gets hot. I've never worked with bronze that much but I've certainly work-hardened my share of copper and that was all kinds of fun when the work piece got a huge crack down the center. LOL
 
Contrary to popular beliefs zing really is not that bad for you. Sure you don’t want to breath it in if you don’t have to. But that goes for anything that’s not clean air. But zinc does not have any lasting affects or cause any permanent bodily harm.
 
I have a real cool vid I’m working on about making bronze and ingots. Keep your eyes pealed
 
Yes, I regularly make a long post about how people misunderstand zinc poisoning in animals with contact with zinc by humans. Metal fume fever, which is a name for the illness welders and other metal workers can get burning on galvanized metal is not fatal ... or particularly harmful.
Zinc forms zinc oxide when heated … which is nearly inert to humans. If it was harmful, it wouldn't be spread all over every kid and lifeguard in America. Any fume is bad to breath -- be it a campfire, frying bacon, or zinc fumes from welding.
 
Thanks, and of course you're right that it isn't terribly toxic. Its possible I'm overly concerned by breathing zinc oxide fumes. It's not something I'm terrified of, just rather not if I can avoid it.
Thanks again.
 
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