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I gotz a foundry!

A place to ask general spud cannon related questions.
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I gotz a foundry!

Unread postAuthor: Brian the brain » Sun Jan 29, 2012 1:38 pm

Yes!!

Thanks to youtube ( and after being motivated right here!) I learned how to make a charcoal fournace capable of melting aluminium!!

My Fridgy died on me so I cut off the top and used the shell as the main body of the fournace.
The aluminium plug through wich the wires connected was drilled out to serve as the air intake.

I put it in an old oildrum filled with dirt and put a pipe through it and hooked that up to the motor and fan out of an old paintstrippergun.

I put in the coals and lit her up.

After about an hour I discovered that I needed to put charcoal underneath the crusible aswell...anyway...I took just 2 pictures when the actual melting had begun...I pured some in a pipe..wich failed to give me solid roundbar...the rest became a nice blob looking thing...


This was just the test...
A very succesful one... :D I succesfully metled aluminium and brass...became a pretty good alloy by accident..harder than the aluminium I started out with.

I will now focus on making molds.
The intension is to pour complete gunparts such as breechblocks for wich I would otherwise need a mill.

I can make the part out of candlewax, pour gypsum around it and let it dry.
Afterwards I'll melt out the wax and pour the aluminium in.
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jrrdw » Sun Jan 29, 2012 2:28 pm

Nice! I was looking at Plaster of Paris for modeling in the store just yesterday. I never worked with gypsum before, is that like Plaster of Paris?
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Unread postAuthor: jakethebeast » Sun Jan 29, 2012 2:30 pm

nice, i once tried making wootz at my coal forge, but it was too hard to prosess with a hammer, so i gaved it to my friend who has power hammer. Melted once some aluminium too, i think my gas forge would be capable of melting aluminium. Soon making new gas forge, it shouöd be capable of melting iron :lol:
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Unread postAuthor: Brian the brain » Sun Jan 29, 2012 2:42 pm

Nice! I was looking at Plaster of Paris for modeling in the store just yesterday. I never worked with gypsum before, is that like Plaster of Paris?


To be honest..I'm confused.
Both gypsum and plaster of Paris translate to Dutch as "gips"

So ...? Wich is it and what's the difference?
Consistancy?
Appearently Dutch people don't need to know.. :roll:

Anyway...I have just learned how useful it can be to insulate the fournace.
This will confine the heat to a smaller area..less loss...
I see guys melting aluminium in half the time.

I need concrete...the foamy kind..
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Petitlu » Sun Jan 29, 2012 3:03 pm

excellent!
were the ancestors of the wax statues and covered the ground, and allow to dry, they melted the wax and then rolled down the metal in the clay mold

EDIT :

Plaster of Paris is very well, I used to make rocket nozzles ...
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Unread postAuthor: jrrdw » Sun Jan 29, 2012 3:47 pm

Wikipedia wrote:Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O.[3] It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale. It forms as an evaporite mineral and as a hydration product of anhydrite.


http://en.wikipedia.org/wiki/Gypsum
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Unread postAuthor: Technician1002 » Sun Jan 29, 2012 4:35 pm

Aluminum burns (turns to oxide) which will contaminate the liquid metal. Before pouring, it is recommended to flux the aluminum and scrape off the top layer of slag.

A good flux to use can be obtained from a spa or pool supply outfit. Use a piece of a Chlorine tablet and toss it in just after you turn off the blower. Use your iron skimming tool to push the tablet to the bottom of the crucible so the gas bubbles up through the aluminum. When the tablet is gone, scrape off the slag off the top and it is ready to pour.

Google these terms together for more on the subject.
fluxing aluminum melts

Congrats are in order for your first foundry. It is not something most people get to try. I was lucky enough to have a Natural Gas foundry in High School. i poured both Aluminum and Cast Iron. The heat from pouring cast iron is way more intense than pouring Aluminum. PPE is required to lift the crucible out of the furnace, otherwise the heat is intense enough to be very uncomfortable from 5 feet away. Being within 3 feet to lift the crucible will ignite all flammables from radiant heat. Heat shielding clothing is a must for cast iron.
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Unread postAuthor: Gun Freak » Sun Jan 29, 2012 5:27 pm

I've been wanting to make one of these too :) Nice job!
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Unread postAuthor: Skywalker » Sun Jan 29, 2012 6:13 pm

I did this on a very small scale several years ago, and it was a lot of fun. I think my favorite part was when I melted a bunch of US pennies down with some copper, trying to make brass. I caught the zinc in the pennies on fire, it was a beautiful yellow-green color, mixed with the blue-green from the copper and red from the charcoal flame.

I managed to melt a bit of pure copper once too, but it dissolved the steel can & became a much harder alloy than I meant to make.

I was also casting while barefooted, and I stepped on a hot piece of steel rod that I'd been poking the coals with ... OUCH.
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Unread postAuthor: Fnord » Sun Jan 29, 2012 8:55 pm

Brian,

When gypsum is heated to around 250F, it undergoes an endothermic reaction and releases water, becoming what is known as 'plaster of paris'.

When plaster of paris is mixed with water at room temp, it reacts with the water and becomes gypsum again. The energy absorbed earlier is released in this process.

You can reuse plaster indefinitely by crushing it up into powder and leaving it in the oven for a while.

It should also be possible to make plaster of paris from scrap drywall, though I haven't tried it.

You're going to burn through that crucible pretty quick. Try finding an old
hpa cylinder or a 3" cap/nipple. I think you're going to rather enjoy casting brass. Aluminum Doesn't always cooperate with me though.

Oh by the way, I have a very old cannonball tutorial in the how-to section for this sort of venture. If you haven't already seen it.

also also, if you're not barefoot when casting a bucket of scary bright orange glowing metal you're doing it wrong. Pants are optional.
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Unread postAuthor: Brian the brain » Mon Jan 30, 2012 3:45 pm

Aluminum burns (turns to oxide) which will contaminate the liquid metal. Before pouring, it is recommended to flux the aluminum and scrape off the top layer of slag.


I scooped off the slag.
That much I knew.
Next time I'll add a chunk of chlorine tablet as a flux.
Some guy on youtube recommended baking soda.I was originally planning on usingthat when the actual moulds will be cast.

You're going to burn through that crucible pretty quick. Try finding an old
hpa cylinder or a 3" cap/nipple. I think you're going to rather enjoy casting brass. Aluminum Doesn't always cooperate with me though
.
I was worried about that seeing people burn through soupcans..

The crusible is some kind of stainless steel.It's got a thick bottom and has survived 100% intact.As brass needs to be 1250 degrees centigrade to melt and no speck can be seen on it it seems better than expected.
Hard as hell!
As it is pretty thin looking I was expecting a comment.

It will have to do untill I find something better like what you suggested.
I have a disposable CO2 weldingbottle I could use...but I really want to use up that gas first.

Would it be possible to encase a brass system in this aluminium/brass mixture?
Would the inner structure be compromised?
Will the alloy stick to it without forming a break between the two?

What I mean is...I would love to construct the inner workings, air channels etc seperately and then pour a nice re-enforcement around it in a desirable shape.
I know this stuff shrinks but that would make it shrink onto the inner bit wouldn't it?

I'd love to get two QEV's close together and attach the plumping on it connecting it to a single 12 gram adapter in the grip.
Only the bare fittings and airlines will be encased.
The pistons and 12 gram adapter would be added afterwards.( cold)
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Gippeto » Mon Jan 30, 2012 5:17 pm

Brian the brain wrote:Would it be possible to encase a brass system in this aluminium/brass mixture?
Would the inner structure be compromised?
Will the alloy stick to it without forming a break between the two?


There are a several excellent casting groups available to you if you join yahoo groups. Lots of knowledge and experience there to help you along...and keep you safe.

Would recommend you join and ask your questions there.
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Unread postAuthor: jackssmirkingrevenge » Tue Jan 31, 2012 1:13 am

Brian the brain wrote:I scooped off the slag.


In the UK you'd probably be arrested for that :D
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Unread postAuthor: Technician1002 » Tue Jan 31, 2012 10:14 am

Instead of an iron or brass crucible which may alloy with your melt, I recommend a high temp pottery such as stoneware. So check the groups. I have only used a real foundry crucible. It was a ceramic of some kind.

Most smaller ones are under $50 delivered in the US
http://www.budgetcastingsupply.com/Crucibles.php

Searching descriptions, I think it was a clay graphite bilge crucible.
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