melting copper question...

A

Allan Molstad

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Where I work we always end up with small sections of left over copper 1/2" pipe.
We also end up with lots of left over copper wire once in a while.
Some of it is new, some of it is old.
The longer lengths the boss will take with him to get money for, but the shorter stuff gets tossed.

I wanted to find a way to use this left over junk to make a guard for my knives.

MY IDEA:
I want to melt the copper!
First I get some of the craft clay that is of the type that you can fire it in a normal kitchen oven and get it hard.
Next I get a pluming pipe end, perhaps a 1&1/2" end cap.

HOW TO GET READY:
Now what I do with the clay is to make a mold of it to roughly the size of the guard I want.
It might be 1/2" high, by 3/4" wide, and about 2" long.
I fire it in the oven to make a mold thats hard clay on the bottom,sides and ends, but is open on the top
I then weld a rod onto the pipe end cap to serve as a handle.

HOW TO DO IT:
Then all I have to do is cut small sections of the copper pipe and place into the inside of the metal pipe end cap and heat until it melts. I could keep adding copper untill I had enough to fill my mold.
Then all I have to do is pull the end cap out of the forge by the welded rod handle and pour the melted copper into the mold and allow to cool.

QUESTION> Would it work?
 
No.
Polymer clays decompose at elevated temperature somewhat above 300 deg F. Way lower than the melting point of copper.
Try sand casting, maybe?
 
copper likes to get a lot of porosity when cast. This is one of the reasons that bronze is cast far more than copper.

WS
 
No, the melting point of the copper is much higher than the steel, mostly due to the higher thermal conductivity. Not to mention as already stated the porsity asssociated with smelting coppper, and the FUMES!!! HIGHLY TOXIC!!! The workers in Peru where they make copper have lifespans that are staggeringly low, but due to the poverty there, they still have no trouble finding workers???:(
It's too cheap to F around with. Just buy the bar stock at any knifemaking supplyhouse.
Matt Doyle
 
The melting point of copper is no where near that of steel. Copper is close to 2000 degrees F and steel is closer to 3000 degrees F.

You can certainly melt copper the way you have described. Your main problem will be that you will loose a lot of it to oxidation, perhaps as much as 50% or more with the wire. At elevated temperature copper really likes oxygen so finding a way to protect the melt is a must. I've heard of people pounding their wire into as solid a lump as possible. A flux of some kind may be necessary, perhaps a pinch of borax and a cover of crushed charcoal may help with the oxidation.

Give it a try, it can't hurt. I did the same trying to make a bit of copper/tin bronze but lost so much copper to oxidation the final melt came out to around 60% copper and 40% tin instead of the 90% copper, 10% tin alloy I was shooting for.
 
Geez, don't be so cheap!

Just buy a little ceramic melting 'crucible with handle--the type with a little spout so you can pour it eaisly. --what are they $20? --while your at it, spring $5 for some graphite stirring rods. (Boric acid is a common casting flux, BTW.)

In addition to the problems Guy has mentioned, if you use a steel crucible, I would expect a lot of contamination because your steel will be scaling pretty heavily before the copper is melted. Those bits will be in your melt.

Just use one of those ladle-shaped ceramic crucibles. You can torch your metal right from the top. You won't be burning holes in a steel can and it will be clean. You just sprinkle a little flux on, torch and pour.

Looks something like this:

http://www.rjsintl.com/productDetails.asp?product_id=C238-4
 
The steel is for the ingot mold. You melt the metal in a crucible or a depression on a charcoal block and pour it into the ingot mold.

All that said, purchasing sheet/bar copper for making mokume, or other knife work is a far better idea than any of this alchemy.
Stacy
 
This is a classic case of "spending a dollar to save a dime". Save your time and buy some barstock and make some knives.Dave:rolleyes:
 
DC KNIVES said:
This is a classic case of "spending a dollar to save a dime". Save your time and buy some barstock and make some knives.Dave:rolleyes:
Click to expand...
well....it just seems a shame to toss this stuff out.

Lets say at work we dig up about 100 ft of 1" copper pipe.
Many times we dig the stuff up in small 1" - 3"sections that due to how busy we are it just is not worth attempting to dig out of the berm pile,save, clean, cut to the correct size and cart down to the place that returns money for it.

many times we just dont pay any attention to the smaller sections of copper we run into.

I just felt that I could have a use for it.
I know that old copper has a lot of junk in it, but I had the hope that a little wirebrush action, and a little cleaning and a 2 foot long section of 1" pipe could be converted into a nice copper guard once melted and cooled in a casting.

And it would make a cool story to tell of my next work knife.
 
well,,,,yes,,,,

That would be smart money-wise,,,,

but a bit of a poor story to tell later...Wheres the magic?...
+++
Here is another idea I think would be cool to be able to do: is to take all the brass sheel caseings left over from deer hunting from all my friends and co-workers, cut the bottoms off, clean real good, melt and turn into something else.

or...

I think it would be a cool story to tell about:
a hunting knife that was made from the truck spring from a truck of your grand dad's,
Brass guard from the shell caseings from your dad,
and an antler handle from the deer you shot...

That would be a hunting knife with a cool story to tell....
 
Well.. While having stories to tell is all nice and good, what if, while attemtping this metallic alchemy, something goes horribly wrong, and blows up in your face? Or anything similar?

Wouldn`t it be better to have some less adventurous stories to tell people yourself,
rather than have some really adventurous stories told about you posthumously?
 
Copper prices are high so sell the scrap and buy some good stuff...Tonight's news had a story about a church where someone cut out the church's water pipes to sell !! Storms in the NW took down many power lines which people took to sell .Some were live and there were at least three deaths from this !!
 
Alan - I gave a long winded explaination to this in your previous thread.

Mokumé gane / Forging Copper

You can form copper pipe into a solid ingot simply by melting and pouring into a small homemade mould.

However, Joe-Caswell is right, if you just want solid copper, it is so much easier to buy a hunk than to fool with copper pipe.

Alan- especially considering your interest in the katana, some research into mokumé gane may be interesting for you as a traditional guard material.

It is essentially a Damascus steel - like material made up of non-ferrous materials, usually copper-based alloys.

The info given was gained from my interest in mokumé gane

In making up the traditional Japanese alloys of Shakudo and Shibuichi, they are both copper based. Some practice in melting pure copper can be useful as a precursor to making the other alloys

Your idea is actually not as far off as you might think, copper tubing as used in plumbing supply pipe is alloy
# ETP 110
Electrolytic Tough Pitch # 110.
It is the recommended alloy for mokumé gane.


Get Steve Midgett’s video & book– (I got it from my college through a loan between colleges)
http://www.mokume.com/bookvid3.html
He shows how to make mokumé as well as prep alloys.

“The Complete Metalsmith” by Tim McCreight is also a good source of general metal working info for jeweler/cutler.

Now the how to ... this is quick & dirty so I recommend the books and videos but that said...

Clean the copper pipe inside & out to reduce scale formation. (I split the pipe with a hacksaw, pound flat and sand inside & outside with abrasive cloth.
Cut up the cleaned copper pipe with tin snips into little bits...
Create a charcoal block from hardwood. Half burn some wood.
Carve a depression in the charcoal to melt into (and a grooved spout to pour with. -Optional)
Make this thicker than you think; the charcoal will burn off as you use it.
Using a REDUCING flame on your Oxy acetylene torch, melt little bits of copper in the depression keeping the torch on it the whole time.
The reducing flame acts as a barrier and protects against oxidation (oxidation = brittleness)
Add a bit of flux such as borax. If pipe is clean, charcoal block & reducing flame mean flux may not be needed.
After it is all melted, the surface shows shiny bright, if not- flux it.

Reduce your oxygen to get a cooler flame and allow the melted copper to solidify.
(keeping flame covering it until solid and cool)


You have the option of carving the depression in the block to semi shape,
or, pouring into a mould you have made of plaster, steel, sand, soft firebrick...

A simple ingot mould can be made from two mild steel plates ¼" thick, a bit of square rod bent into a U shape and a small c clamp.
The thickness of the rod determines the thickness of the ingot.
Flare out the top of the U – provides a sprue and improves density...
Clean the steel,
Coat all pieces contacting the copper with carbon by flaming the steel with a dirty acetylene flame.
-this acts as a release agent to prevent sticking.
Put the U between the plates and clamp together.
Preheat the mould in a toaster oven at 350F to ensure it is dry- improves density, reduces voids
Pour into the mould, keeping the reducing flame covering the copper at all times.

After the cast, the ingot will be a bit porous and will benefit from a light cold forging.

When planning your ingot, keep in mind 1” x 1” x ¼” solid lump will weigh about 1.4 oz (40 grams)


When forging copper,
Annealing and forging are opposite to steel.
Heating to red then slow air cooling hardens, not softens,
Cold forging causes work hardening and requires annealing on reductions of approx 1/3.
To anneal- heat to a red heat and quench in water.

Copper alloys are considered“hot short” - meaning it is brittle at red heat.
Forging to shape is done cold, or at a black heat (colder then red heat-hard to judge-work in the dark)

This info all applies to silver as well.


Steven Penner
 
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