I Was Thinking Of Casting My Own Geocoin, Using a TB numer to track it. Options

[SomewhereInND]

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.

[ar_kayaker]

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....

[NFA]

try tin or pewter...I bought some off of Ebay, and cast the coins in molds dremmel-ed out of soapstone...I think they look cool.

Jamie - NFA

[welch]

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.

[darus67]

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

Excellent series of books for the resourceful DIYer. I have the first 2.

If you want to do a 1 shot experiment at melting aluminum with little investment necessary check out my
Coffe Can foundry

[Team JSAM]

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?

[ar_kayaker]

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.

[SomewhereInND]

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)

This post has been edited by SomewhereInND: Jun 2 2006, 03:29 PM

[Totem Clan]

Hey Somewhere, If you do get this going give me a yell. I'll throw in with you as much as I can. I've been thinking of make a personal coin anyway.

[dhenninger]

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.

This post has been edited by dhenninger: Jun 1 2006, 06:45 PM

[Eartha]

Definitely don't use lead! Not that you were going to.....

[SomewhereInND]

UPDATE # 2 FROM ORIGINAL SENDER

After previous replies, and after looking into it more, I found a place that will sell me 25 lbs of casting sand for $40.

Another alternative to aluminium is tin, it has a lower melting point. But is apperently is not very easy to come by.

[SomewhereInND]

I am going for it, here is a link to a webpage about my casting of a geocoin
http://www.geocities.com/bryhar0/geocoin.html

The server has a 4meg/hour download limit, so if it doesn't work for you, come back later.

This post has been edited by SomewhereInND: Jun 4 2006, 08:01 PM

[Nacaya]

I am going for it, here is a link to a webpage about my casting of a geocoin
http://www.geocities.com/bryhar0/geocoin.html

The server has a 4meg/hour download limit, so if it doesn't work for you, come back later.

No images there? Or is it just my PC that is angry with me?

[SomewhereInND]

No images there? Or is it just my PC that is angry with me?

Because I haven't got that far yet, I will fill in images as I complete them.

On the webpage it in red, it says something like the following

The rest are my plans, or parts on oreder....

[SomewhereInND]

FIRST MELT
http://www.geocities.com/bryhar0/geocoin.html

Haven't cast a coin yet, but I did make a muffin that will last for ever (or until next melt)

Ran into some problems with the crucible, will have to work them out. Still waiting for casting sand.

[BlueDeuce]

Some of those final pictures aren't coming up for me.

[SomewhereInND]

Some of those final pictures aren't coming up for me.

Becuase just above those missing pictures, in big red letters it says

"THIS IS AS FAR AS I HAVE GOT, THE REST ARE PLANS, OR PARTS ON ORDER"

This post has been edited by SomewhereInND: Jun 13 2006, 03:36 PM

[Billy Goatee]

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.

[BlueDeuce]

Some of those final pictures aren't coming up for me.

Becuase just above those missing pictures, in big red letters it says

"THIS IS AS FAR AS I HAVE GOT, THE REST ARE PLANS, OR PARTS ON ORDER"

Me no read, me like pictures.

[SomewhereInND]

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

I am just making a one sided open face mold, I want to keep it simple. Another words, there will only be an image on one side or the coin.

[Midway Cafe]

Hi,

Lots of good info in this old thread. Casting Geocoins

I would recommend working your way through several metals starting with the lowest melt points and getting progressively hotter. Mistakes will happen and there is less time and money invested in the lower melt point metals.

MC

[2cvdriver]

Brobdingnagian Geocoin, LE (Gold)

[b]How about this geocoin! It is listed as a geocoin but has a TB tag stuck to the back. BTW - Makes it an interesting hike carrying it in/out.