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Author Topic: Investment Casting a Tarantula  (Read 4351 times)

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MrsWTownsend

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Investment Casting a Tarantula
« on: March 08, 2015, 03:15:48 PM »

Here are pics of casting my tiger rump.  These were used in an article a gal on an artsy fartsy forum I used to frequest did around Halloween one year.  I may or may not be able to find that link...  it was a few years back.

My poor dead Tiger Rump, buttless.  He was a good little T, unfortunately males are much shorter lived than females.



Melting a wax sprue on dead T's body- this is the channel for the melted silver to flow into the cavity



In the base mount and in the flask


This the silver button, after the T has encased in casting investment and then burned out in the kiln.  You ramp up the heat over about 2 hours per temperature incrementt, to what the temperature of the metal you are using is in it's liquid state then let the flask soak in the kiln for several hours.  You have to make sure whatever is inside has enough time to burn out completely before you try to cast- most organic things can be used.  Often times skulls tend to have a thicker area that does not burn out which will leave an area inside the investment cavity where metal can not flow and/or the liquid metal will encase the leftover part, probably leaving some of it exposed.


The cast tarantula, after it has had the majority of investment removed.  Basically, you give the flask time to set, until you see the metal button has cooled to a non-glowing state, then you quench it _we use a 10 gallon trash can) and the bulk of the investment boils off in the water.


Using my Foredom, I cut the cast piece from the sprue and grind down and blend the gate, then depending on the item I have cast, tumble it in stainless steel shot or use my ultrasonic tumbler (designed for preserving detail, it uses basically small pieces of guitar string for the tumbling media).  In this case, I use the ultrasonic tumbler and burnishing liquid.


Then of course, give my T a butt and he is memorialized forever in sterling silver.



Well I found the page on the forum where I originally posted pics back in 2009 but I can't find the lady's Halloween blog article.  Oh well.  :)
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Enchantra

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Re: Investment Casting a Tarantula
« Reply #1 on: March 08, 2015, 04:05:46 PM »

Awesome!  Thanks for posting this Gina!  I remember when you first posted this online.   :headbang:
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Bentiron

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Re: Investment Casting a Tarantula
« Reply #2 on: March 08, 2015, 05:42:03 PM »

nice job on the spider :headbang:
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iceopals

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Re: Investment Casting a Tarantula
« Reply #3 on: March 08, 2015, 06:36:17 PM »

I love it!  Still need me one of those!
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wampidy

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Re: Investment Casting a Tarantula
« Reply #4 on: March 08, 2015, 11:39:11 PM »

Wow, that is way cool. Can you make one of my brother? He is still living, would that make a difference?
Jim
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iceopals

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Re: Investment Casting a Tarantula
« Reply #5 on: March 09, 2015, 06:53:38 AM »

Ha!  Yeah, I've got a brother that needs...  No, never mind.   :LOLOL:
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Enchantra

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Re: Investment Casting a Tarantula
« Reply #6 on: March 09, 2015, 07:04:04 AM »

LOL!!!!
I created a forum of wise crackers!  I love it!   :LOLOL: :LOLOL: :LOLOL: :DRUNKS:
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A man wearing a helmet defending his country should make more money than a man with a helmet defending a football!!!  (From an email message I received - so true!)

MrsWTownsend

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Re: Investment Casting a Tarantula
« Reply #7 on: March 13, 2015, 01:47:15 PM »

Wow, that is way cool. Can you make one of my brother? He is still living, would that make a difference?
Jim

I will need a bigger flask

and kiln

and crucible

but once he is in the investment he will probably stop moving  :)  it could be doable
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PhilNM

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Re: Investment Casting a Tarantula
« Reply #8 on: March 13, 2015, 02:39:45 PM »

Hi. great..... but a couple questions....
Did you pre coat the T with anything pre investment?
And you skipped the wax impression completely so the silver melted and birned out the organic matter for a one time piece?
Thanks!
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MrsWTownsend

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Re: Investment Casting a Tarantula
« Reply #9 on: March 13, 2015, 08:26:09 PM »

Hi. great..... but a couple questions....
Did you pre coat the T with anything pre investment?
And you skipped the wax impression completely so the silver melted and birned out the organic matter for a one time piece?
Thanks!


Hi Phil!

I did spritz the T with an anti-bubble solution prior to investing.  This is a one shot deal- how it works is, the organic matter actually burns out at a lesser temperature than what is required to heat the flask to in order to allow the metal to flow through the investment, so during the time you are ramping up the kiln and allowing the invested flask to soak in the kiln, the wax or whatever you have encased in the investment burns out.  I am doing centrifugal casting, so at the time I take the flask from the kiln to slam that molten silver into it at the speed of liquid metal light (:D), there is actually an empty cavity which is [hopefully] perfectly formed to the shape of what was once inside it.

This is why it is important to assure that whatever you encase in the investment isn't too thick to not burn out at the melting point of your chosen metal- skulls, for example, have an area where the bone is too thick to burn away completely, that is the same reason why after cremation they have to pulverize the remaining pieces.  A mouse skull would probably burn out...  Leaves, wax, fabric...  I have never tried like a plastic thing- I am not sure that would work out well either...  It would stink, that's for sure...

When I do the scorpions, I sometimes use super glue on the leg joints to sort of reinforce their little legs as they are posed when the investment is poured over them.  I use the anti-bubble solution on everything that I can if I am sure it will not ruin the piece, to prevent air bubbles from sticking to it.  I keep it in a spray bottle and apply it that way.
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RxScram

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Re: Investment Casting a Tarantula
« Reply #10 on: March 13, 2015, 08:40:53 PM »

Very cool!
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iceopals

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Re: Investment Casting a Tarantula
« Reply #11 on: March 14, 2015, 07:11:00 AM »

Aha!  So you are not using your original casting to create molds?  I just assumed.  Sorry!  I did some casting years ago.  I have all of the rigs, vacuum casting, mold making.  But I went chicken-shit.  (I can say that here, right?). I was heating the metal before casting and apparently my hose had a micro-leak near the torch.  My hand lit up and I was known as the blister queen by the Dr. and hospital.  It covered the entirety of my palm, one blister.  So I have been afraid to go back.  I really want someone who is comfortable with casting to come hold my hand a few times.  Oh well, eventually.   :glasses9:
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MrsWTownsend

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Re: Investment Casting a Tarantula
« Reply #12 on: March 14, 2015, 01:32:55 PM »

No.  While I do have the technology, I have not actually made any vulcanized rubber molds. 

Really sorry to hear about YOUR experience!  How horrible and painful that must have been!!!  :(
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PhilNM

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Re: Investment Casting a Tarantula
« Reply #13 on: March 14, 2015, 01:50:39 PM »

Thanks. all the lost wax casting I've ever done (very little) used molds to create many wax "masters". Nice to know for things that would be difficult (like hairy spiders, crickets, other insects, etc) I can "go direct".
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Sandsave

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Re: Investment Casting a Tarantula
« Reply #14 on: March 14, 2015, 03:42:58 PM »

Great info, I was trying to figure out how you replace the t with metal. So they have to be dried out first? Or be small enough to burn up?
I can't think of anyone I want a cast of lol
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PhilNM

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Re: Investment Casting a Tarantula
« Reply #15 on: March 15, 2015, 11:30:44 AM »

Another question, if I may.... when you did the burn out, did you have to do it upside down so all the ashes and etc fall out or just leave them in there to be encased in the metal?  Are you using silver or german silver? White bronze maybe? Silver is getting so darn expensive, but white bronze is only $13/lb approx. I want to do some bees..... and maybe a beetle or two...
Thanks!
Phil
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MrsWTownsend

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Re: Investment Casting a Tarantula
« Reply #16 on: March 15, 2015, 08:33:25 PM »

I use sterling silver casting grain metal and once in a while silver scraps get mixed in.  Here are a couple of sources for casting grain metal:

http://www.hauserandmiller.com/fab/grain.html
http://www.gsgold.com/casting-grain/casting-grain.html

I did buy brass to cast with, but that was for the stick bugs that turned out to be too big for my flask.  :(

Here are some more pics to help explain the flask orientation a little bit:

The items being cast get fused onto a sprue, which is then mounted into a rubber base


The flask is then seated over the sprued items on the rubber base, which closes one end of the flask.  The flask is basically a metal pipe cut to length.



The item is encased in investement, which is basically super fine material very similar to plaster.   After the investment has sat for 24 hours and had plenty of time to cure, you remove the rubber base.  The button is placed on the bottom side in the kiln.  I should mention here that we use a vacuum shaker table to pull all of the air out of the investment immediately after pouring.



Heated to temperature


Husband using borax to clean the crucible before we melt the metal.  We also use the borax to burn out impurities in the silver while we melt it




Place the heated flask directly from the kiln to the cradle, keeping the metal heated


Then using centrifugal force it is spun into the flask cavity


Our highly technical set up


Give the metal time to set in


Then quench the flask



And fish your item out of the bottom of the bucket to see if it turned out good



On this one, they didn't all fill in.  I put A LOT of items on one sprue though. LOL  To ensure a good cast, make sure each sprue is constructed to each item in such a way to allow the metal to flow without much obstruction, make multiple if need be, and don't overload it.

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iceopals

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Re: Investment Casting a Tarantula
« Reply #17 on: March 16, 2015, 06:53:48 AM »

Ha!  You forgot the most important part!!   That centrifugal caster is scarier than hell!!!   :LOLOL:
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RxScram

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Re: Investment Casting a Tarantula
« Reply #18 on: March 16, 2015, 07:25:42 AM »

Wow... just... wow.  I have a long way to go!
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Helene Fielder

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Re: Investment Casting a Tarantula
« Reply #19 on: March 16, 2015, 09:14:41 AM »

This could go under tutorials.  Its a great one thanks.
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Helene

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Re: Investment Casting a Tarantula
« Reply #20 on: March 16, 2015, 11:15:05 AM »

This could go under tutorials.  Its a great one thanks.

Done.
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Re: Investment Casting a Tarantula
« Reply #21 on: March 16, 2015, 04:34:17 PM »

Thanks!
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