Metal Casting: Tips and tricks! (MODS Please Archive!)

[Rook 3]

A while back we had a thread that was started by Hydin, a thread that asked several questions about how to cast items in metal.

Several people (I can only remember Theatrix and Megatron?) posted personal experiences and suggestions on what to do and NOT do, as well as safety concerns/experiences.

And despite repeated requests to archive the thread, it's gone now and the information is lost.

SOOoo... I propose that those in the know please offer their insights again.

Web links to materials or pre-existing tutorials are a plus.

Thanks in advance,

Rook

 

[hydin]

yea

i looked for it when i got back to the board, and apparently a thread that has a lot of information in it isnt worth archiving.

maybe we can start up a new one though, specially since i still dont have any metal casting equipment

chris

 

[replicaprops]

I have been fooling with metal casting for a little while.
I did a few parts in lead from old fishing weights.

I think the best info source on this topic has been www.backyardmetalcasting.com

I have personaly been attempting lost wax casting. I have had some good success with this when I did a vader shroud and some other parts.
Sand casting seems like its made for large objects rather than small detailed parts.

I can tell you that in lost wax casting, you should use the wax made for the process. Candle wax does not burn out clean enough to make a good cast. Also, if your doing anything hotter than 600 degrees use the proper mixture of plaster and sand, The plaster of paris I used tends to get very brittle when burning out the wax.

 

[Scott]

The wax casting, I believe, is what you see in the prologue of LotR, just FYI.

 

[Xeno Kenobi]

I heard from 5postboy that sand is what they use for molds. For High Quality Industrial molds use metal.

 

[Rook 3]

Here's a couple of the sources that were listed in the last discussion.

I found them while crawling through the mountain of forgotten links in my own archives.

Metal Casting Supplies

http://www.miniaturemolds.com/mainframe.htm

They sell a 20/1 by weight RTV siliconewith a max temprature
of about 700 degrees, which should be good for casting pewter.

The small-ish kit (2.2 lbs) is about $45 for the silicone and catalyst.

Other Metal Casting Supplies Sources

http://www.imperialinfo.com/sca/pewter.htm

Metal Casting Tutorial

By Theatrix.

http://home.att.net/~tk1066/Casting.htm

Enjoy!

Rook

 

[TK2692]

The Theatrix tutorial you are looking for the link to is the last link in your post.

TK-2692

 

[CJP]

What's the typical shrinkage rate when casting with metal?

Chris

 

[Cyland Props]

I learned lost wax casting in High School along with aluminum casting, now 14+ years ago ouch! For lost wax casting you want to use investing compound which is a fine grain powder that doesn't shrink with heat and doesn't retain water like plaster. I've always wanted to run into a centrifugal caster at a swapmeet so I could do some killer casts.

For white metals the silicone mold method will work well when you make the mold walls real thick to hold the weight of the metal. Basically the same things used for resin casting is followed. Powder the molds with talc, wire the molds shut or make a metal box to go around it and heat the molds before casting. As for shrinkage the parts tend to expand do to the weight and cooling. For a vader shroud (rotj) I made, the inside shrunk back about a 1/16" so the hole instead of being 1 1/2" it was now 1 5/8"

 

[Rook 3]

How many white metal casts can you do in a row before you start damaging the mold?

Is there a certain length of time you should wait between pours?

Rook

 

[theatrix]

</SPAN><TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD CLASS=$row_color>
Rook 3 wrote:<HR></TD></TR><TR><TD CLASS=$row_color>
How many white metal casts can you do in a row before you start damaging the mold?

Is there a certain length of time you should wait between pours?

Rook
</TD></TR><TR><TD><HR></TD></TR></TABLE><SPAN CLASS=$row_color>

We did approx 1000 castings in 2 molds of 3 copies/positions each. The molds showed little or no deterioration. Regarding how long to wait, I first dust the molds with graphite, rub it in and then start casting. Normally, we get around 5-10 sets of castings from the Silicone RTV (platinum catalyzed) before they molds are "too hot". We then set aside the warm mold and switched over to the cool one. Repeat as needed.

How hot the mold gets depends greatly on how large the cast object is. You can tell the molds are getting too warm for good casting by touch (i.e. how warm they feel through the gloves) and by the fact that the silicone molds start to deflect (i.e. edges don't line up right).

Also, this only applies to the 2 part platinum catalyzed silicone RTV that we use a lot. Other silicone/vulcanized materials can behave differently.

 

[phase pistol]

How can it be the "lost" wax method if YOU guys know how to do it...

- Karl

 

[WolfMorganFX]

Here's my metal casting set up...

Cheap & easy, everything from Home Depot...

I use the same silicone molds I use for my resin pieces, & a propane torch for the heat source... All you have to do is liberaly coat the molds with talcum powder, & prewarm them for about a minute in the microwave...

My crucible, a 1.5" copper endcap, with a dowel handle screwed to the side, the base is a wood block with an old CPU heatsink...

1# roll of silver alloy plumbers solder, solid wire ( No flux!!!) About $12 a pound... This stuff is excellent, & make a very strong, solid casting, that cleans up beautifuly... Looks just like pewter or sterling silver...

Examples, you can do both small & large castings with this setup, with excellent detail...

Any questions, feel free to ask...


Wolf

 

[Dusza Beben]

Would an open face mold made of high fire ceramic (stoneware) work for casting small items in metal? I want to cast my Naboo SOG emblem (Below left in my banner) for use on my armor and as a hat insignia. Sculpting it is no problem. And I've got a kiln and plenty of clay.

DB

(edit; clarified [ I Hope

] )

 

[kimncris]

I tried silver solder a couple of times, but I found that I got much better detail using Kurt's SFProps brand metal.

Otherwise I pretty much do the same thing as above, melting the metal right in the ladle (stainless food ladle) with a propane torch and pouring into regular old silicone molds.

-cris

 

[Rook 3]

Do you have to re-dust the molds after every pull, or can you do a couple before needing to re-dust?

Where do you get "Kurt's SFProps brand metal?" Cost/weight?

The "pewter" metal from miniaturemolds.com is about $7.00/10oz

Rook

 

[WolfMorganFX]

The medallion would be a snap to cast, but a silicone mold is your best bet... I think a clay mold would pretty much be a one shot deal, like casting into plaster molds...
I dust my molds before every pour, keeps them from burning out or losing detail to quickly...
The other solder I use is the 60/40 tin/lead solid wire... It's esentialy the same mix as the casting ingots, & it works extremely well for crisp detail, & costs less than the silver solder... I use both, depending on the castings I'm doing... I've found the tin/lead mix tends to burn out quicker than the silver when remelting scrap pieces or bad casts (meaning the castings get duller & more brittle, & often have more flaws)... Occationaly I'll mix them half & half, to revitalize remelted pieces... I also clean the slag off with pretty much every use, so it keeps the impurities to a minimum...


Wolf

 

[Emuyshondt]

What is best to dust the molds with? Talcum Powder, or this Graphite powder I read about? (Had never heard of graphite powder before).

Are there any particular pros and cons to using one or the other?

Where could graphite powder be bought?

Also, do you dust the molds after each use (I'd assume so), or as needed?

Does anyone here know the heat tolerances of Smooth-On Mold Max and Oomoo series silicones?

A lot of questions, I appreciate the help of you all though.

Thanks!

-EM

 

[Emuyshondt]

-!-

 

[kimncris]

</SPAN><TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD CLASS=$row_color>
Rook 3 wrote:<HR></TD></TR><TR><TD CLASS=$row_color>
Do you have to re-dust the molds after every pull, or can you do a couple before needing to re-dust?

Where do you get "Kurt's SFProps brand metal?" Cost/weight?

The "pewter" metal from miniaturemolds.com is about $7.00/10oz

Rook

</TD></TR><TR><TD><HR></TD></TR></TABLE><SPAN CLASS=$row_color>

I found it best to "dust" with dust made from the same metal I was casting (just rub on some sandpaper) and I did it every time.

Try PM'ing SFProps about his particular formulation. I think it was about $11 per pound. He used to do a bulk order now and again.

Like I said, I found it very easy to work with.

-cris