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I Was Thinking Of Casting My Own Geocoin

SomewhereInND

By SomewhereInND
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SomewhereInND

+SomewhereInND

Posted
Posted

A few years back, while sitting at a campfire, a fellow hiker had a melting pot that he put in the campfire, and melted down a alum. can. I dont remember how 'liquid' it got, but it gave me an idea that maybe I could do the same, and cast my own geo coin/TB, reusing my TB numbers that are no longer in this realm.

 

I could always use coal and/or an airsupply to get a hotter temp, maybe bronze is easier.

 

I could also run a test using lead free solder, that would probably make it really easy.

 

Has anyone done something like this?

 

I am about to start searching the internet, I will let you know if it goes anywhere.

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ar_kayaker

+ar_kayaker

Posted
Posted

I've considered something like that myself, though my plan was to use new TB numbers. I basically haven't gotten around to it yet because it's been kayaking season for the past several months and geocaching has taken a back seat.

 

Lead is easy to melt and easy to find (any tire shop has pounds and pounds of used wheel weights) but is kinda soft and not so good for the enviroment. (melting point 327)

 

Tin and zinc are harder to come by but also have real low melting points (232 & 419 respectively) not sure how well they hold up to handling but they at least aren't toxic.

 

Now if you have good hot coals rather than a common fire, Aluminum melts at 660. It's about as common as grass, stands up to reasonable abuse and can be engraved pretty easily. I haven't tried casting with it so I'm not sure how well it takes to a mold, but no special equiptment is needed, just a good bed of coals and something to melt it in.

 

After that things get a little harder and more expensive. Silver has the next best melting point at 893 (sterling, pure siler is 860) and gold melts at 1063 (24k). On the other hand if you have the means of reaching 1100 degrees copper is much, much cheaper and melts at 1083.

 

Brass is an alloy of copper and zinc (85/15 mix) that melts around 950 and bronze is a mix of copper and tin (90/10) that melts right around 1000. I don't know if simply melting and mixing the metals would be enough to make the alloys or not.

 

Hope this helps..it has certainly refreshed my own memory and renewed my interest in casting some TB's....

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welch

+welch

Posted
Posted

A few years back, while sitting at a campfire, a fellow hiker had a melting pot that he put in the campfire, and melted down a alum. can. I dont remember how 'liquid' it got, but it gave me an idea that maybe I could do the same, and cast my own geo coin/TB, reusing my TB numbers that are no longer in this realm.

 

I could always use coal and/or an airsupply to get a hotter temp, maybe bronze is easier.

 

I could also run a test using lead free solder, that would probably make it really easy.

 

Has anyone done something like this?

 

I am about to start searching the internet, I will let you know if it goes anywhere.

Never done it, you made me think of this book.

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Team JSAM

+Team JSAM

Posted
Posted

I've considered something like that myself, though my plan was to use new TB numbers. I basically haven't gotten around to it yet because it's been kayaking season for the past several months and geocaching has taken a back seat.

 

Lead is easy to melt and easy to find (any tire shop has pounds and pounds of used wheel weights) but is kinda soft and not so good for the enviroment. (melting point 327)

 

Tin and zinc are harder to come by but also have real low melting points (232 & 419 respectively) not sure how well they hold up to handling but they at least aren't toxic.

 

Now if you have good hot coals rather than a common fire, Aluminum melts at 660. It's about as common as grass, stands up to reasonable abuse and can be engraved pretty easily. I haven't tried casting with it so I'm not sure how well it takes to a mold, but no special equiptment is needed, just a good bed of coals and something to melt it in.

 

After that things get a little harder and more expensive. Silver has the next best melting point at 893 (sterling, pure siler is 860) and gold melts at 1063 (24k). On the other hand if you have the means of reaching 1100 degrees copper is much, much cheaper and melts at 1083.

 

Brass is an alloy of copper and zinc (85/15 mix) that melts around 950 and bronze is a mix of copper and tin (90/10) that melts right around 1000. I don't know if simply melting and mixing the metals would be enough to make the alloys or not.

 

Hope this helps..it has certainly refreshed my own memory and renewed my interest in casting some TB's....

 

How many total coins are you making?

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ar_kayaker

+ar_kayaker

Posted
Posted

How many total coins are you making?

 

I'm not sure if you were asking me or the original poster, but I only plan to make a few, at least at any one time. My general plan was to make unique items (not necessarily coins) cast in metal with the TB number either stamped, engraved, or cast directly into the item. I might make repeats of designs I really like, but not likely more than five of any one design.

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SomewhereInND

+SomewhereInND

Posted
  • Author
Posted (edited)

UPDATE #1 FROM ORIGINAL SENDER

After looking into this, I will try the following hopefully within the next month, the following is information I obtained from the web (how reliable is it? I don't know!).

 

I am going to use aluminum, and a high btu propane burner, and a small cast iron dutch oven.

Does anyone know how many btu I am going to need? I saw a website where someone used a propane fishj fryer, and that it melted easy.

 

I was also told the best aluminium to recycle, is aluminium that was originally cast. I have an old subaru engine sitting in my yard, the overhead cam, and pistons are cast aluminium. I should be able to break off a few reasonably sized pieces with a sludge hammer. Cans produce only 40% aluminium, and does not cast very well.

 

When melting the aluminum, you should put an agent into the mix so that it is easier to remove the slag. I found a website, but can't find it again. If I remember right, it said to add Mortans salt substitution, which makes the slag easier to remove. If anyone runs across this site, or has other suggestions about this, please post it.

 

The one sided mold is going to be made out of plaster of paris. PLEASE READ REST OF PARAGRAPH, BECAUSE THIS CAN BE DANGEROUS. If there is any water in the plaster, it will explode when hot aluminium is pored on it. To prevent this, I am going to make a very thin mold that is 1/4" high 4" X 4" and make an impression in the mold. To prevent the explosion, I am going to bake it overnight in an oven at 150, this should get the moisture out. I am also going to keep the mold hot until the pour, so that it does not absorb any moisture. You should use casting sand, but I can't find any in the area. There is special plaster designed for casting, but of course IO can't find any in the area. Ill try normal plaster, being EXTRA careful. Some people say they get great results, Others say that the normal ingrediants in plaster have a lower melting point the alum and mold will degrade, or mold will crack/explode, etc... So I don't know what results will be.

 

I will post results (if I am alive, and still have fingers)

Edited by SomewhereInND
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dhenninger

+dhenninger

Posted
Posted (edited)

Update from original sender.

After looking into this, I will try the following hopefully within the next month, the following is information I obtained from the web (how reliable is it? I don't know!).

 

I am going to use aluminum, and a high btu propane burner, and a small cast iron dutch oven.

Does anyone know how many btu I am going to need? I saw a website where someone used a propane fishj fryer, and that it melted easy.

 

I was also told the best aluminium to recycle, is aluminium that was originally cast. I have an old subaru engine sitting in my yard, the overhead cam, and pistons are cast aluminium. I should be able to break off a few reasonably sized pieces with a sludge hammer. Cans produce only 40% aluminium, and does not cast very well.

 

When melting the aluminum, you should put an agent into the mix so that it is easier to remove the slag. I found a website, but can't find it again. If I remember right, it said to add Mortans salt substitution, which makes the slag easier to remove. If anyone runs across this site, or has other suggestions about this, please post it.

 

The one sided mold is going to be made out of plaster of paris. PLEASE READ REST OF PARAGRAPH, BECAUSE THIS CAN BE DANGEROUS. If there is any water in the plaster, it will explode when hot aluminium is pored on it. To prevent this, I am going to make a very thin mold that is 1/4" high 4" X 4" and make an impression in the mold. To prevent the explosion, I am going to bake it overnight in an oven at 150, this should get the moisture out. I am also going to keep the mold hot until the pour, so that it does not absorb any moisture. You should use casting sand, but I can't find any in the area. There is special plaster designed for casting, but of course IO can't find any in the area. Ill try normal plaster, being EXTRA careful. Some people say they get great results, Others say that the normal ingrediants in plaster have a lower melting point the alum and mold will degrade, or mold will crack/explode, etc... So I don't know what results will be.

 

I will post results (if I am alive, and still have fingers)

 

I did this with lead-free silver solder and a plaster mold. you can check out my coin

 

I made about 15 of them, the first one being trackable with a number recycled from a lost USA geocoin

 

I baked the plaster casts in the oven at least over night 250+ degrees, then i heated them to about 700 degrees in a small furnace borrowed from work, and I still had some problems with the molds bubbling the solder and especially cracking. The plaster I used was "casting" plaster from a local art store. I made the molds by cutting my design out of stamp material (carvable rubber) and used that to make the plaster molds.

 

If you have any questions i might have a little insite, but I never perfected it. I really wanted to make a few out of silver (1450' F), but I never did it.

Edited by dhenninger
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Billy Goatee

+Billy Goatee

Posted
Posted

The first foundry I used was a metal 5-gallon bucket lined with refactory cement, and a hole in the bottom, which a propane weed burner was inserted. It got hot enough to melt brass.

 

If you plan on brass, the sand molds tend to 'float' so you will need to tie them together.

 

remember to use a sprue and riser, so you know that the mold took (the metal will rise in the riser)

 

There are plans you may find on the internet that you can make a forge out of scrap pipe. (The one I have is 10" pipe, about 2' long.

 

For a crucible, you can weld a bottom on some heavy-gauge pipe, any more heat than what aluminum needs, you will need graphite.

 

Also, the lost wax method will give you even more detail than sand casting.

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