[Jonathon G]

I am currently tring to forge a dagger from a copper alloy and would greatly appreciate any help someone could supply in the way of forging techniques. This alloy is roughly 60 % copper and 40 % aluminum.

Thank you for any help or info you can give

[B. Stark]

Forging as in shaping the blade?

[Chris M.]

well your dealing with an aloy that wasnt available in the copper period being that theres aluminum in it. so i dont know how it would hammer forge.
copper anneals the oposite of steel. heat it to a medium red and quench it. then you can hammer forge it if you wish. be carefull because the melting point is not to far from the red hot point.
traditionally many cultures made a stone mold (just called a stone)and poured melted bronze and copper (whichever you were using)into it. after it cooled the stone was unbound and pulled apart and the sword removed. the mold was then put together for another go.
again im sorry i cant comment on how cold forging aluminum copper alloy would work. copper is easy with a ball peen hammer. but i think the aluminum would offer alot of resistance and possible be toxic if heated in a forge.

[Jonathon G]

thank you both, and yes, to shape the blade.
All that i have available in my area is 'most likely' industrial grade copper alloy. I am not even sure that this is an alloy at this point, and i don't know how to determine this other than a general idea of what it was used as before. My only 'real' source for materials that i know of is my local recycling center. I had thought a bit about aluminum being toxic but was unsure as to weather it would produce harmful fumes when heated.

Even ANY general tips on cold forging would be of great help because i can't find any literiture on the subject and this would be my first time crafting anything from a metal.

Thank you again,
Jonathon

[Chris M.]

www.anvilfire.com go to the iforge section

cold forging is just forging with no heat. quite popular for bending sheet steel around a form to make armor with a rubber mallet/hammer these days.
as for material, junk yards will give you old leaf springs and sheet metal just to get rid of it or at a very low price. mine thanks me for helping him clean up and get rid of disposal fees

[Jeroen Zuiderwijk]

If you've got traditional tin bronze, it's hot short. This means you can only shape it cold, and by repetitive annealings to remove the workhardening. I don't know if aluminium bronze is hot-short. You could try a small piece, heat it up and see if you can shape it without it falling apart. Cold working can be very tricky, especially when the metal workhardens fast. The faster it hardens, the more unpredictible it will be when the material cracks. So if the material doesn't have hot-shortness, you'd probably be better off forging it at high temperatures, which will also take a lot less force. But of course you have to keep in mind the melting point of the material.

[Peter Johnsson]

Aluminium bronze can be hot forged.

I am not sure about the alloy you have. It might have a higher aluminium content than the type I have used.

The thing to be mindful about is that overheating will make the material crumble like cake. Forging too cold is hard work and demands frequent annealing (I would say it is just about impossible to do any real shaping of this material with cold workng).

At a solid strawberry red, the bronze will forge easily with a feeling of tough toffey. It flows much easier under the hamer than iron or steel, as long as you do not overheat. Heating up till orange red might damage the material and result in grain growth and fracture.
At a duller red the material still flows nicely under the hammer. You can forge dimensions by hand that would need a powerhammer f you would be using steel or iron.

It is a good idea to forge at increasingly lower temperatures as you come closer to final dimensions.
You can then cold forge the edges to work harden them.

The blade will still be soft enough to be fileable, but because of the special character of bronze you will need a good new sharp file to remove material without too much frustration.
With a less than sharp file it s like trying to file hardened steel: the file will slide over the surface only making slight surface scratches, without removing any material.
I also recommend having a good honing stone at hand for final surface finish. Emery paper wrapped around wood slats is also fine for removing coarser marks.

You can get a pretty decent edge on a blade of aluminum bronze. It will also be strangely difficult to bend, even in thinner dimensions. Small deformations when hitting harder targets is to be expected, but it is possible to cut knotty wood without much dulling or damage to the sharp edge. You can restore full sharpness with a honing stone and a leather strop to hair popping sharp. Depending on what things you cut, you will have to resharpen more or less often. Wth materials like bronze, the truth that the effectivness of the tool depends on the skil of the user is quite evident.
You need a blunter final edge angle on bronze than you would on steel. Experinment with the correlation between main bevel and final sharpness. Different tools need different combinations. For a dagger purely to be used as a weapon I would suggest a strong mid rib, thin main bevels that go down to less than a milimeter before the final sharpness is shaped. Such a blade is not good at chopping hard wood, but will slice and cut softer materials very well.

Aluminum bronze resist most common patiantion methods as it is a type of "stainless" alloy used for things like propellers on sea going ships. Expect your blade to remain a golden yellow hue with very little darkening over time.

Again: I am not sure about the alloy you have got, but you should be able to get a fairly good idea after some testing. Take a small sample and test forge it att increasingly higher temperatures: you will notice where the window of working temperature is, its upper and lower borders. Final cold workng is not so much about shaping: the material is too tough for that. You might compress a one milimeter edge into almost sharp, but do not expect to do much plastic deformation in overall shaping while working cold.

If you cannot get a good heat source for hot forging (I like using my popane forge for this, as it is easy to see the temperature of the blade n the open furnace), try grinding the piece to shape and only cold work the edge bevels and mostly the last 5 mm towards the edge.

Good luck, and do let us know the result!

[Jonathon G]

I am not really sure how hard the bronze alloys are for comparison but what i currently have is about the same hardness as gold, the final blade wont really see combat but be more of a religious tool so i don't need it to have a razor edge. As for heating the metal i only have access to an oxygen/acetalyn torch and a propane torch so any recommendations would be great. When i finish with it i will be sure to post a few pic here.

[Shawn Shaw]

A propane torch is more than adequate for heating up copper. I've used a small gas torch to make copper bracelets and such with no trouble at all.

[M. Eversberg II]

Check out

http://s8.invisionfree.com/bronze_age_center

They're mostly bronze age guys but we sometimes talk copper.

M.

[Jonathon G]

Also, does anyone know if a pure or almost pure copper NEEDS to be tempered or if it will be fine if just hardened?

[Dan Howard]

Does anyone know of an example of an extant weapon that was made of pure copper? Even the earliest blades seem to have been alloyed with arsenic.

[Shawn Shaw]

Just for yucks...what kind of alloy is a penny? I think there's a lot of nickel but I'm wondering if I'd get anything workable by melting some pennies in my forge and hammering the result into a blade?

[Bryce Felperin]

[Shawn Shaw]

Here's a related question-how does one weld copper? Suppose I had a copper sheet and wanted to fold it and thereby make it thicker, what would I do? I presume you would need some sort of flux to inhibit oxidation but I don't know...

Any thoughts?

[Jeroen Zuiderwijk]

[Jeroen Zuiderwijk]

[Jonathon G]

I have looked into where it came from and have learned that it a VERY good chance what i have is 99.9% pure copper (it was a bus bar from a GE warehouse)

[Chris M.]

braising is the only way i know to join copper but it would leave an air pocket

[Douglas S]