An idea: A LEGO Casting Clamshell

[Dopug]

i'm dying to knoiw if that key worked? i bet it would with a little bit of filing here and there. good work

[aka.decoy]

Looks cool man...great idea.

[mister sour]

This should be sticky'd!!! I'm going to make one also. Thanks for the cool idea!!

[MBI]

Wood's metal is one of the lowest priced fusible alloys so it is commonly used in casting applications like this. Like I mentioned in the chat window the other night, also consider trying Cerrosafe. It's a little more expensive than Wood's metal but it delivers very accurate castings.

Cerrosafe is used by gunsmiths to make extremely precise casts of gun chambers because it has interesting expansion and contraction properties. After casting, once it solidifies it contracts slightly, making it easy to remove it from the mold. Once it's cooled after about an hour, it's precisely the dimensions of the original. This is the best time to take measurements of the casting if you need to keep a record of the information. This is also a good time to use the casting in a key duplicator to make a proper working copy of the key. After that time, the casting will slowly expand over the course of a week until it reaches it's final size, which should be around a couple thousandths of an inch larger than the original.

As a safety note, both Wood's metal and Cerrosafe are toxic and contain lead and cadmium. You shouldn't cast either of them unless you're in a well ventilated are (preferably outdoors, with a fan or breeze blowing any fumes direcly away from you). Also avoid allowing the temperature to get too high, in the case of Cerrosafe, keep the temp below 195 °F. Wash well with soap and water after handling the metal, or any of your casting equipment.

A non-toxic alternative is Field's Metal but it's rather pricey. It also has a much higher bismuth content so it probably contracts after cooling more than Field's or Cerrosafe. If you decide to go this route you should probably take measurements of a test copy at periodic intervals after casting to compare to the original to see if it will be accurate enough to make a reliable duplicate.

I don't know if this is the best price for Cerrosafe, but it's available in 1 lb ingots for $46 and 1/2 lb ingots for $29 at Brownell's, a gunsmith supply place.
http://www.brownells.com/.aspx/pid=384/ ... TING_ALLOY

[macgng]

THANKS for the link MBI! Yo Chem, see how it goes with the resin. The reason I didn't buy the casting resin is because I knew it was probably gonna cost just as much as the casting metal (and I was right).

My friend makes jewelry so I'm going to call the art supply store this week and see what kind of low temp casting metals they have. If they don't have the right metal, they will definitely have the other supplies I will need: Oil based modeling clay and the casting ladle.

EDIT: ooh found this place to buy CerroSafe: http://www.rotometals.com/Low-Melting-Alloys-s/21.htm Low 144 and everything above Low 281 are LEAD FREE. Thanks barbarian for that first link, but I just don't want to be melting it in the house if it has lead in it.

[MBI]

THANKS for the link MBI! Yo Chem, see how it goes with the resin. The reason I didn't buy the casting resin is because I knew it was probably gonna cost just as much as the casting metal (and I was right).

EDIT: ooh found this place to buy CerroSafe: http://www.rotometals.com/Low-Melting-Alloys-s/21.htm Low 144 and everything above Low 281 are LEAD FREE. Thanks barbarian for that first link, but I just don't want to be melting it in the house if it has lead in it.

Thanks for the link. They have some very low prices.

Low 158-190 is Cerrosafe.
Low 158 is Wood's Metal.
Low 144 is going to be Field's Metal, thus the higher price.

I just researched it a little more and found a few places that said Wood's Metal expands a lot more than Cerrosafe as it cools. No one seemed to have any specific data as to how much though, so I don't know if it would rule it out for key casting.

Here is a chart I found for Cerrosafe with specific contraction and expansion rates, over time, measured in inches per square inch.

•2 minutes -.0004"
•6 minutes -.0007"
•30 minutes -.0009"
•1 hour +-.0000"
•2 hours +.0016"
•5 hours +.0018"
•7 hours +.0019"
•10 hours +.0019"
•24 hours +.0022"
•96 hours +.0025"
•200 hours +.0025"
•500 hours +.0025"

I also found an MSDS for Cerrosafe, file attached.

Low 158-190 (CerroSafe) MSDS.pdf

[Alera]

Great, now my little brothers will be able to get into my door with compliant ease. Much appreciated ~_~