Instructables

Metal Casting with SUGRU

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YOU CAN CAST ACCURATE TIN REPLICAS OF OBJECTS USING SUGRU

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Not to long ago, I started my ventures into metal casting. My early molds were made of plaster, but I quickly learned that silicone epoxy makes GREAT metal casting molds. Unfortunately, the silicone epoxy I was using was not designed for casting metal, and was too soft and flexible. My early silicone molds were not tough enough for lots of repeated use.

But Sugru, on the other hand, is a very durable silicone mold making material. It makes molds just as good as the silicone epoxy I used previously, except Sugru is WAY more durable, and will make molds that will last dozens of casts.

The cast quality of this skull isn't quite exactly what I'm after, but I was in a hurry. Molds need to be broken in before they with make great casts, so the first, second, or even third castings may have bubbles or vacancies. The skull in the main picture is the second cast. You shoulda seen the first one ;)

Ok, this goes without saying (but I'll say it anyway)...
Casting metal involves the use of butane torches. Butane torches have fire. Fire can burn you. So can hot metal. Got it?

If you want to cast high temp metals, just use the sugru molds for wax, then use the lost wax casting process.

There are several people in the comments arguing about fumes. They have not actually done this instructable, so they wouldn't know. Anyway, if you use solid lead free solder, there will not be any fumes. I know this from experience. Please, though, trust your own judgement and use common sense!

 
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jamob9 months ago
I have 2 questions. If this works with lead and tin would it work with zinc from pennies? Just wondering because I find zinc to be safer than lead. Also what stores sell Sugru?
stoobers jamob6 months ago
Zinc melts a few hundred degrees hotter than lead or tin. Sugru probably wouldn't hold up to zinc.

Lead is not dangerous unless you dump it on yourself, eat ground lead dust or acid soaked lead, or breath excessive fumes. Probably avoid it if you are a child or are pregnant. Lead toxicity is mostly just a scam. People live their entire lives with lead bullets stuck in their bodies. You don't hear about them whining.

A zinc melt of pennies has WAY more heat in it than lead, so I would rate it as more dangerous than lead, by a long shot. HOWEVER, it pours like silver vodka so it is awesome. You really need to protect against spills, since there is so much more heat - you don't want it to drop onto sneakers or that space between your shoe and ankle.
noahspurrier11 months ago
Don't use a copper pipe endcap as a crucible or ladle. The pool of molten tin will disolve the copper walls of the cap and eventually spill out. While the melting point temperature of pure copper may be higher than your propane or butane torch, the melting point temperature of a copper/tin alloy is not. I have attached some photos that shows what happens when a small amount of tin is melted in copper. I used an ordinary propane torch with no additional oxygen.

An "iron bottom-pour casting ladle" is the best thing to use for this kind of work, but I just use a "4 inch cast iron DWV blind plug" as a crucible and ladle. I welded on steel rods for handles. DWV stands for "Drain Waste Vent". This kind of pipe is also sometimes called "Soil Pipe". Cast-iron DWV fittings are available at any hardware store. DWV fittings don't use threads. In the old days cast iron soil pipe was soldered together with big pools of lead. You can still find "plumbers ladles", which are perfect for tin. Also search for "cast-iron lead pots", "cast-iron lead dippers" and "bottom pour casting ladle".
copper_tin_1.jpgcopper_tin_2.jpgcopper_tin_3.jpgcrucible_2.jpg
ithica20121 year ago
oh sorry forgot vasaline (patroulem jelly) should not effect the casting
ithica20121 year ago
hi new here but try heating your mold in an oven till its bout 200 f should help a lot mettel binds up in cold molds
Rowen271 year ago
I realize this comment is extremely late, but in reading this, it occurs to me that the reason your castings are odd for the first few runs is likely due to the mineral oil used in the initial molding process... You might get better results if you use a degreaser in the mold before the first cast. This of course is all speculation on my part, so take it as you will... I'll be giving this instructable a try in the near future, so hopefully I will be able to get back to you with a definitive answer before long...
chamunks3 years ago
Would you not suggest using silver solder?
It would be cheaper to buy silver casting grains - Silver solder is not pure and will contain other metals.

It would also be very expensive.
Foxtrot702 years ago
I like the Instructable. I find that I can use this info readily for a new employment I am about to start which involves prototyping and fabrication of obsolete parts. I also have a silver plated wine decanter set that needs two of three replacement stopper caps, fortunately I can use the remaining one as a my pattern, wish me luck.

As to concerns by folks about fumes, some are real and not immagined. The thing is for anyone do your homework on the materials you are using. Next there are Instructables that show how to build a power ventilated work area that address these very issues. If you have an old range hood vent these can easily be converted to provide a power ventilated work area. Remember, "Nothing, is not impossible... Nothing, just takes longer to accomplish." Keep up the good work!
Be cautious - the solder is in fact largely lead with a small amount of tin added.

This would not be suitable for food use.
evindrews2 years ago
You know... I wonder if you could make key "molds" so if you lost your key to your house, you wouldn't need to buy a new key..?
The metal in use wouldn't be strong enough.
samark25862 years ago
Can anybody tell me what material should i use to make a mold for aluminium melting? I need a mold to be re-useble.
Sand casting? you don't say how big the mold is.
When the weather gets a bit warmer I plan to do aluminum casting using charcoal soldering blocks. You carve your design in one charcoal block, melt the metal directly in the mould you have created then use another block to force the metal into all the crevices of the mould. (place uncarved block on top of molten metal and push down) . You will want to make sure you have a stable work surface so that when you apply pressure you don't end up spilling the molten aluminum. Years ago, when I worked at a jewelry store I used this technique to cast gold jewelry so I think aluminum will be easy enough. I think the charcoal block would hold up to several castings but size may be a problem as the charcoal blocks I have seen were designed to do soldering on and were not overly large. If someone knows how to make a charcoal soldering block I'd sure like to hear how.
nepheron (author)  samark25862 years ago
For aluminum you will need to use some kind of clay or oil sand. Molten aluminum will destroy sugru.
doesent tin have a higher melting point? so why does aluminum destroy it but not tin?
nepheron (author)  curvy772 years ago
Nope, tin melts at 232 C and aluminum melts at 660 C.
but iv melted aluminum soda cans in a tin soup can before.
Most "tin cans" aren't really made of tin. Most modern soup cans are made of steel, which melts at approximately 1370 C.
tinker2342 years ago
wow thanks is there a way i could use a tin soda can as a source of metal
Your soda can is either steel or Aluminium!
FrozenIce2 years ago
okay so i wanna make a mold for a hotwheels car, and i only need the top metal part. how do u sugest i do it using sugru?? (yes i will dismantle it first
klayla2 years ago
So you're casting with solder? That doesn't seem like a very good idea as solder tends to pit when casted. Just curious, interesting instructable though.
larryihnots2 years ago
Simple and motivating for beginners as I !! Definately on my way to the blog now. Thanks for your innovativness !.
small skull bead is an understatement. look at that thing! its like the size of an led head!
jimmiek3 years ago
How high a temp will this material stand before it won't work (in degrees F please, I don't do Euro measurements)
You can use google for many things including unit conversions. for instance if you type the following in to google's search bar; "204.44 degrees celcius into degrees fahrenheit" you will get the conversion. or go here for even more google awesomeness; http://www.google.com/help/features.html I even use google to translate languages into english, and if you use google chrome as your web browser, it will ask you if you would like a foreign website translated in the browser...... Hope this opens up some doors for you Jimmiek! Rog
nepheron (author)  jimmiek3 years ago
A naked flam will instantly wreck the Sugru.However, the Sugru website says it can withstand 400 degrees F or so. It certainly withstood molten metal being poured in...it's pretty tough stuff!
TIP: if you make semi-random cuts in the sugru to split it it'll go back together a lot more accurately!
stormende3 years ago
Nice ible, you got my vote.
I do lead castings for solders as a hobby, and there are always little things that I would love to add on, but most DIY casting kits cost about $60 and will only make one or two good molds. This method is awesome. As if I didn't need yet another reason to get Surgu.

One tip for this. Where you have a space in the back of your skull for the pour to go, you can always just place a spacer there and mold around it.
nepheron (author)  atombomb19453 years ago
I'm really glad you like this!
All those lead casting kits are is an ''epoxy-silicone'. Nothing special, but at the prices they sell it for you'd think it made of diamonds or something.

Sugru is the same material as the silicone in the soldier casting kits, except sugru has a solvent that evaporates instead of a chemical reaction. The end result, in either case, is just plain old silicon.
Just as a friendly correction, silicone rubbers aren't epoxies. Epoxies are specific family of organic resins. Silicone polymers are a different kettle 'o monkeys entirely.

This is the second time I've seen mold making silicones referred to as "silicone epoxy" or "epoxy silicone" here on Instructables. Never seen that miss-term before anywhere else, dunno how it came about.
nepheron (author)  nepheron3 years ago
ahem, the last word 'silicon' was meant to be 'silicone'. Silicone is not equal to silicon LOL
dhfj
the $60 DIY MOLDING KIT IS NOW DIAMONDS!!!
quote: Where you have a space in the back of your skull for the pour to go...

firstly you'd have to drill a hole in your skull, you'd need a mirror, but usually such procedures are handled by a neurosurgeon, and the person is under general anesthesia... LOL!  Gotcha!  :):):)

I use Freeman V330 / CA45 silicone rubber with a shore A30 for my low temp castings and epoxy resin castings. The 1 kg (2.2 lb) kit only cost $35 US and holds up great for many many castings. Also you can use Amazing Mold Putty for low temp metals as well and you get 1/2 lb for around $20 US and is very flexible for those bad undercuts.

@nepheron - Great instructable and LMAO at all of the Lead issues people are talking about. I say if your afraid then you should not be doing this in the first place :)
Jax
Man! That is awesome!!!! nice job!!!
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