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Author Topic: How'd they do that?  (Read 568 times)

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Offline Cornbelt

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How'd they do that?
« on: January 09, 2009, 06:48:23 AM »
How in the world did they manage to cast hollow shells out of cast iron? Was it some kind of process like a ceramic slip mold, or some kind of decomposible core, or ...????
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Offline Artilleryman

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Re: How'd they do that?
« Reply #1 on: January 09, 2009, 07:42:14 AM »
Sand core. 
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Offline Cornbelt

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Re: How'd they do that?
« Reply #2 on: January 09, 2009, 07:54:51 AM »
They use some kind of water soluable sand glue to be able to get it out of that little bitty hole?
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Offline KABAR2

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Re: How'd they do that?
« Reply #3 on: January 09, 2009, 08:39:07 AM »
No glue, sand is compressed to hold it's shape the little bittey hole is how it attaches to and is supported in the mold molten iron is then
cast into the mold and allowed to cool, the sand is then broken up and shaken out of the ball, the little bittey hole is usually reamed with a taper to hold the wooden fuse holder. hope that helps.


Allen <><
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Offline dan610324

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Re: How'd they do that?
« Reply #4 on: January 09, 2009, 09:18:11 AM »
they mix a little syrup or oil to the sand to help it hold together during the pour
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Dan Pettersson
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interested in early bronze guns

better safe than sorry

Offline Artilleryman

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Re: How'd they do that?
« Reply #5 on: January 09, 2009, 09:51:14 AM »
Too much moisture content in the sand will cause a casting problem.  When the moisture is heated to steam it has to go someplace.
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Offline dan610324

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Re: How'd they do that?
« Reply #6 on: January 09, 2009, 10:03:24 AM »
yes , but its absolutely impossible to use only dry sand , and water is not good .
very little oil or syrup is whats used today and it was even used back then
today they also use some other chemicals some times thats hardened with gas , but I dont know exactly what it is or the english names , in swedish its called waterglass and hardened by carbonmonoxide I believe .
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Dan Pettersson
a swedish cannon maniac
interested in early bronze guns

better safe than sorry

Offline Cat Whisperer

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Re: How'd they do that?
« Reply #7 on: January 09, 2009, 11:07:43 AM »
The sand used for the core is generally different from the sand for the rest of the mould.

Core pieces are made up, sometimes baked, and then suspended inside the cavity.  Easier to do if you can suspend the core in more than one place.

After casting and cooling the flask is dumped, the green sand broken off and oil added for future use.  Then the core is broken up - sometimes not easy, it takes some work to get it all out.  The core sand is not reused to my knowledge.

There is a foundary in the town where I work - half owned by Ford - that makes exhaust manifolds, transmission housings, differential housings and such.  They have some wonderfully curved and intricate cores and moulds.  Production line.  3 pots of iron - each 10-12' in diameter and about that deep.  Quite and event when the pour.  Dirty filthy work - they go at it 8 hour shifts, 3 shifts a day, 7 days a week.  Shut down 2 weeks every 6 months and maintenance folks replace every motor they have time for.  Makes me enjoy being able to cast bullets once a week or so.



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Offline GGaskill

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Re: How'd they do that?
« Reply #8 on: January 09, 2009, 11:22:01 AM »
Chemically, waterglass is sodium silicate, and it is hardened with carbon dioxide.
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Offline dan610324

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Re: How'd they do that?
« Reply #9 on: January 09, 2009, 11:29:19 AM »
ok then I was close   ;D
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Dan Pettersson
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better safe than sorry

Offline Cornbelt

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Re: How'd they do that?
« Reply #10 on: January 09, 2009, 11:43:20 AM »
Well I learned something today. Thanks for the knowledge. Even found out something else to do with waterglass besides soak eggs.
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