Casting your own parts

[Mario Lucchini]

Finally I discovered a high temp rare earth that withstands some 2500 ºC....

Easy to find and mighty cheap, it's found where the ceramists buy their goodies....it's a mixture of 4 or 5 special sands that are mixed in some strange proportions, anyway, they sell it ready to use and already mixed....

On the other hand, as metal, I'm using zamak , which is a mixture of tin, lead and bismuth, and which has a melting point of about 300 ºC, it will melt with any household torch....I used a jewellers minitorch which works with lighter gas....by the way, this metal can be polished to a high shine and will keep it, can be painted, lacquered, tampered with, drilled, tapped, you name it!

In a copper gas cap (Or any other suitable metal container), you put the sand (Which comes moistened), and using any styrene part of any kit you want to reproduce, you give the plastic part a shot of WD-40, blow out the excess and carefully press it into the sand ...more carefully withdraw it...if you comitt an error you just reasemble the sand and try again...

This mould should be left to air dry at least 48 hours, melting metal on it with just any hint of moisture in it can lead to a most nasty explosion!...BEWARE and use gloves and goggles every time...

Once the mould is dry, the torch is applied to the mould itself and you bring the metal bar until it melts and fills the mould....the mould gets red hot in this operation and this ensures the metal will get in all the crevises....to enhance this effect, I give the mould some taps holding it with a small plier, on the surface I'm working on....

Let this apart to cold naturally, it takes about 15 minutes (Depending on the mould's size)

Now you can pry your part off the mould and the best parts begins....the cleaning, deflashing and polishing of your cast part.....Most rewarding!

In pic 1 you can see the misterious mixture of sands...

Pics 2 & 3 shows a mould ready to be used...

Pics 4 & 5 shows the finished part once cleaned, polished, drilled and tapped ...

Pic 6 shows the mini torch I'm using...

And the last pics shows the part in use, in combination with scale hardware, turned aluminum part, attaching bracket, and else, reproducing a gasoline filter found on some Alfas of the era...
This is to show that the mixing of scratchbuilt parts can give your model that different look and make yourself most happy....

Mario

[sydeem]

WOW - that is an impressive tutorial. You did forget to mention the name of the mysterious sand

"it's a mixture of 4 or 5 special sands that are mixed in some strange proportions, anyway, they sell it ready to use and already mixed...."

Sounds like it is key to the process. Also when I looked up Zamak - there are some 7 different varieties. I assume you are using Zamak 2?

[46SuperDeluxe]

I'm interested in finding out more about this molding product. From Art School and my early career with ceramic molds, I am pretty familiar with different ceramic clay mixtures. The temp range that you gave indicates probably a porcelain clay body which is a mixture of different clay bodies but primarily kaolin clay. I see that you are in Chile, and I'm wondering what I could find in California US that would be the same. In a foundry, sand with a binder is used in the cope and drag process to cast,say, aluminum. But your product doesn't appear to be sand but rather [I]plastilina ceramica[/I] or special ceramic mud that cracks and shrinks a little as it dries. Is this correct? Is it sold in the can as you pictured? Is it intended for casting or for art projects? anything more that you could tell me about this would be appreciated. Thanks,- Gary

[Mario Lucchini]

WOW - that is an impressive tutorial. You did forget to mention the name of the mysterious sand

"it's a mixture of 4 or 5 special sands that are mixed in some strange proportions, anyway, they sell it ready to use and already mixed...."

Sounds like it is key to the process. Also when I looked up Zamak - there are some 7 different varieties. I assume you are using Zamak 2?

Hey Syd!
After looking at the various Zamak alloys I would say Zamak 3 is the closest to the one I'm using....

Good castings!

Mario

[Mario Lucchini]

I'm interested in finding out more about this molding product. From Art School and my early career with ceramic molds, I am pretty familiar with different ceramic clay mixtures. The temp range that you gave indicates probably a porcelain clay body which is a mixture of different clay bodies but primarily kaolin clay. I see that you are in Chile, and I'm wondering what I could find in California US that would be the same. In a foundry, sand with a binder is used in the cope and drag process to cast,say, aluminum. But your product doesn't appear to be sand but rather [I]plastilina ceramica[/I] or special ceramic mud that cracks and shrinks a little as it dries. Is this correct? Is it sold in the can as you pictured? Is it intended for casting or for art projects? anything more that you could tell me about this would be appreciated. Thanks,- Gary

Hey SuperDeluxe!

The ceramic sand I bought is rather what you call "plastilina ceramica", which shrinks a bit when drying. It also cracks sometimes but very little.
The guy who sells it here told me it has more than 6 components, but not even with a pistol at his head he was going to tell, hee,hee...

It is very finely grained, so the mould resolution is very good in detail...

They sell it to ceramists to make moulds that they put in the oven over 1000 ºC....
That's all I can tell you....

Other that it's very cheap, 500 grams of it costs here your equivalent of US $ 25.00
( 500 grams makes a LOT of parts)

Hope this enlightens the subject a bit more...

Cheers

Mario

P.S. The pics shows other parts made with this method...

[RC-Archer]

That's very cool!! I've done some small metal casting using RTV and lead free solder (aka silver solder)

So what are those parts?

[hot ford coupe]

Outstanding. This looks ideal for my applications. The castings look perfect.

[Switchback]

What about two part molds?

[flamefink]

I have some parts this would be perfect for.

Has anyone here in the US had any luck finding the "plastilina ceramica"? I've been searching google for a possible outlet but can't find any websites in english that make mention of it.

[RC-Archer]

Try here:

Modeling Clays - BLICK art materials

I'm still not sure WHICH clay would be suitable.

[Mario Lucchini]

Try here:

Modeling Clays - BLICK art materials

I'm still not sure WHICH clay would be suitable.

I think non of those products withstands 2500 ºC...

[46SuperDeluxe]

I'm sorry but i've misused the term plastilina ceramica. I thought this term meant literally "ceramic clay." My Bad! Plastilina modeling clay is not suitable for this application- it is not a ceramic clay. I ran a conversion on the temp range and its about 1800+F which is considered lowfire in ceramics. There are pottery clays in this range available at potters supply places in plastic bags that are sold ready to use. I guess as long as the clay is given time to dry, pouring Zamak , white metal, lead, tin etc. into one of these molds would be similar to Mario's mold material since these alloys and metals all melt in the hundreds of degrees where these clays are intended to be fired in a kiln oven to over 1800 degrees or hotter which turns the clay hard like coffee cups and dinner ware. I have used a lowfire modeling clay for small sculpture. Does anybody remember ever making stuff for their parents in grade school or Indian Guides? I think the stuff that I used was from Laguna Clay Co. in southern Cal. but they distribute nationally. I was surprised when I saw Mario's post because I would never have considered using clay in this manner. But if it works- Wow. I'm not sure how a two piece mold would be made. Maybe put some kiln wash on the dry side then put wet clay onto it for the back side. The first side would probably absorb moisture from the second side and crumble though. Again- sorry for the confusion-Gary

[hot ford coupe]

Keep up the great work, guys. Keep coming up with suggestions for this application. You can also look at a few dental lab supply companies that sell casting investment. They're made to cast gold and metals that melt even higher than gold. They'll definitely stand up to the low fusing metals.

[Don Garrett]

Good stuff Mario...this is basically sand casting or investment casting .
You guys may have better luck googling "sand casting " or "investment casting " instead of searching for the brand that Mario is using.

Here' a sample of what I found.......
PetroBond Foundry Casting Sand

[ScaleMotorcars]

Ive used ashtray sand and 30w motor oil with good results. No water to steam off so you can usually get a good casting with fine detail and minor surface defects.

Also Ive read that ground up cat litter is perfect for sand casting . Its made up of bentonite clay and if I'm not mistaken that's the same stuff used in most industrial sand casting .

For for my 2 cents. Most pewter/lead/tin based metals melts under or around 400* so you can use a wide variety of materials. Regular old plaster and many RTV rubbers are good for at least a few castings. Cast resin wil work a few times but do it outside. Some release toxic fumes. Silicone chalking will work but keep the thickness to a minimum and use something like cast resin or plaster as a backing for support. I could go on and on but you get the ideal.