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'[EE]:: Casting Alumin[i]um'
2007\07\22@213749 by Russell McMahon

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I see I sent this to the wrong address originally.
Try again.
I have a requirement to cast a special Aluminium* part. Very low tech
and low tolerance requirement. Precision and material composition are
suitably undemanding that I may even be able to do it with no prior
experience of metal casting. But maybe not :-)

Any comment on home casting to meet my requirement would be of
interest. If this is ever going to happen (and odds are it isn't) it
would have to be reasonably easily accomplished. This seems possible
but past experiences with Murphy suggests otherwise.

This page offers large amounts of apparently useful material on the
subject.

       http://www.backyardmetalcasting.com/index.html

This page offers some brief but useful advice re the effect on iron
content caused by using iron crucibles.

       http://www.smokstak.com/forum/showthread.php?t=33715


           Russell



___________

FYI I'm (only) considering casting a "heat sink" for my wood burner to
greatly improve it's useful heat output. This is a metal box with a
high temperature 'glass' door. The firebox hangs inside a larger steel
air sleeve. As built heat output from the fire is a very small
percentage of that produced by the fire.

Only the external top of the firebox is easily accessible.
By placing various forms of heatsink on the top of the firebox and
then blowing air around the air sleeve we get far far more heat out -
probably about 5 times as much - maybe more. The informal heatsinks
are OK but it's obvious that if I fitted a single heatsink covering
the whole top of the firebox and suitably finned it that I could get
an optimum amount of heat out by adjusting air flow. A cast aluminium
top plate 'simply' needs to make good enough contact with the steel
firebox top and have adequate finning. Fin surface need not be high
quality or even especially even. The plate bottom may benefit from a
post casting 'skim' but if it can be flat within a few mm overall it
would probably suffice.

Top surface is about 500mm x 500mm and total available height for
heatsink is about 90mm. That's a LARGE heat sink by most standards.
Doing this with commercial heatsink sections (even available surplus
ones) would be prohibitively expensive.

Heatsink could be cast in several smaller sections. Depending on fin
to total volume ratio this could get rather heavy. Space described
above is about 25 litres. At a 20% volume fill that's about 14 kg of
Al. How dense the finning can or should be depends on airflow
requirements and I haven't yet come to grips with what's required to
calculate this. A modestly forced blown system (as at present) is
probably best. The upper limit on air blowing rate is my wife's (low)
tolerance of fan noise.

An alternative is spot welded thin fins on a thickish Al sheet. Gets
quite expensive if you can't utilise scrap.



* Where you are it may be an Aluminum part. Here it's not :-)


2007\07\22@215939 by Roy

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Sound interesting, I may benefit from the same idea :-)

Post a photo or two when you have finished so that I can better steel your
idea :-)

I have a couple of large heat sinks, may try putting them on top of my pot
belly to see if I can get a similar result.
_______________________________________

Roy Hopkins             ZL2RJH
Tauranga
New Zealand
_______________________________________


2007\07\22@222532 by Jay Arnold

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Well, it certainly is do-able, its really a matter of:

1. Risk-aversion
2. Budget

I would suggest the hobbycasting yahoo group for a wealth of
information, but if you are only looking to cast a single part, I would
suggest trying to have the part machined by a local machine shop as the
cost of equipment necessary for safe casting will begin to add up
quickly. Off the top of my head, you'll need some minimal metalworking
tools (metal cutting bandsaw, drill press) and welding capability.
You'll need to create a furnace, burner, steel pipe crucible, and
various tools for handling/lifting/pouring the hot crucible. It is an
absolute requirement that you work in a very well ventilated area
(burner is propane fired), as well as have a large sandbox in which the
furnace and pouring takes place. Molten aluminum is somewhere around
1250 degrees F, and crucibles fail, pours splatter, etc. If you are
still interested, I had very good luck with lost foam casting, and would
suggest this versus trying to work out greensand.

Russell McMahon wrote:
{Quote hidden}

--
Jay Arnold
Stealth molds, LLC
(719)229-3041

2007\07\23@001234 by Mark Hanchey

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Darn it !
Now I see a use for the kiln that the local high school sold at an
auction I was at for 25.00.
It was electric and lined with ceramic bricks, the school used it for
pottery class.

Kind of big, but at the time wasn't interested in making vases :)

Mark


At 09:36 PM 7/22/2007, you wrote:
>I see I sent this to the wrong address originally.
>Try again.
>I have a requirement to cast a special Aluminium* part. Very low tech
>and low tolerance requirement. Precision and material composition are
>suitably undemanding that I may even be able to do it with no prior

2007\07\23@024022 by Rich Satterlee

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backyardmetalcasting has reference to a booklet for sale.  This site has some
of the construction information along with a DIY forge using bricketts and
flowerpots:

http://homepage.ntlworld.com/v.ford/furnace.htm

Also there is reference in an *OLD* popular mechanics book of putting in some
sal amoniac into the melt and skimming off the sludge that forms at the top
to get a good pour.

There is also commercial powder that does the same thing.

There are a couple more sites on backyard castings.

http://www.anvilfire.com/FAQs/

Has some information on gas burners etc.


Note that many folks use cast off lawn mower gas engines for sources of scrap
metal.

"Heatsink could be cast in several smaller sections." <--> sounds like a good plan.

Hope these little tid bits help!

No, I haven't done it myself.

 Cheers,

  Rich S.


---- Original Message ----
From:                Russell McMahon
Date:                Sun 7/22/07 18:46
To:                PIC List
Subject:        [EE]:: Casting Alumin[i]um

I see I sent this to the wrong address originally.
Try again.
I have a requirement to cast a special Aluminium* part. Very low tech
and low tolerance requirement. Precision and material composition are
suitably undemanding that I may even be able to do it with no prior
experience of metal casting. But maybe not :-)

Any comment on home casting to meet my requirement would be of
interest. If this is ever going to happen (and odds are it isn't) it
would have to be reasonably easily accomplished. This seems possible
but past experiences with Murphy suggests otherwise.

This page offers large amounts of apparently useful material on the
subject.

       http://www.backyardmetalcasting.com/index.html

This page offers some brief but useful advice re the effect on iron
content caused by using iron crucibles.

       http://www.smokstak.com/forum/showthread.php?t=33715


           Russell



___________

FYI I'm (only) considering casting a "heat sink" for my wood burner to
greatly improve it's useful heat output. This is a metal box with a
high temperature 'glass' door. The firebox hangs inside a larger steel
air sleeve. As built heat output from the fire is a very small
percentage of that produced by the fire.

Only the external top of the firebox is easily accessible.
By placing various forms of heatsink on the top of the firebox and
then blowing air around the air sleeve we get far far more heat out -
probably about 5 times as much - maybe more. The informal heatsinks
are OK but it's obvious that if I fitted a single heatsink covering
the whole top of the firebox and suitably finned it that I could get
an optimum amount of heat out by adjusting air flow. A cast aluminium
top plate 'simply' needs to make good enough contact with the steel
firebox top and have adequate finning. Fin surface need not be high
quality or even especially even. The plate bottom may benefit from a
post casting 'skim' but if it can be flat within a few mm overall it
would probably suffice.

Top surface is about 500mm x 500mm and total available height for
heatsink is about 90mm. That's a LARGE heat sink by most standards.
Doing this with commercial heatsink sections (even available surplus
ones) would be prohibitively expensive.

Heatsink could be cast in several smaller sections. Depending on fin
to total volume ratio this could get rather heavy. Space described
above is about 25 litres. At a 20% volume fill that's about 14 kg of
Al. How dense the finning can or should be depends on airflow
requirements and I haven't yet come to grips with what's required to
calculate this. A modestly forced blown system (as at present) is
probably best. The upper limit on air blowing rate is my wife's (low)
tolerance of fan noise.

An alternative is spot welded thin fins on a thickish Al sheet. Gets
quite expensive if you can't utilise scrap.



* Where you are it may be an Aluminum part. Here it's not :-)


2007\07\23@040931 by Roger, in Bangkok

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Here's the perfect group for you Russell.  I seem to recall some members
there from NZ, certainly many from OZ.    A few hams as well general elex
enthusiasts. <http://groups.yahoo.com/group/castinghobby>

My suggestion would be lost foam casting ... check your high schools and
community colleges for foundry access as well.

Regards/Roger, in Bangkok
DANG ... I didn't even forget the link!

On 7/23/07, Russell McMahon <spam_OUTapptechTakeThisOuTspamparadise.net.nz> wrote:
>
> ...
>
> Any comment on home casting to meet my requirement would be of
> interest. If this is ever going to happen (and odds are it isn't) it
> would have to be reasonably easily accomplished. This seems possible
> but past experiences with Murphy suggests otherwise.
> ...

2007\07\23@063832 by Michael Rigby-Jones

picon face
Russell,

Probably 15-20 years ago I can remember my uncle casting a new mount for his outboard motor (essentialy a very thick wall alloy tube).  As he worked for my grandfathers agricultural engineering business, he probably had somewhat better facilities than you might, but it was a crude operation nonetheless.  The raw material came from old tractor pistons, of which a plentifull supply was available.  The alloy was melted in a heavy steel container using oxy-acetylene, and the mold was simply made using the outer steel housing of an old oil filter and a piece of steel tubing in the center, with one end capped.  After maching the mount was put into many years of service, and as far as I know is still working fine.

Regards

Mike


>{Original Message removed}

2007\07\23@091306 by Recon

picon face
Russell McMahon wrote:

{Quote hidden}

Russell:
check out this website.  They have a lot of books on various subjects.  
The methods may be up to 100 years old but they all work and get the job
done.

I am not sure what the shipping will be but they do get books in the
mail the same day as the payment clears.  A person I know set up a brass
casting  and aluminium casting for small items using the books from this
company.

RECON

2007\07\23@103856 by John Ferrell

face picon face
If you chill the smoke you get lots of flammable deposits in the chimney...

John Ferrell    W8CCW
"Life is easier if you learn to plow
      around the stumps"
http://DixieNC.US

{Original Message removed}

2007\07\23@142033 by James Newtons Massmind

face picon face
> If you chill the smoke you get lots of flammable deposits in
> the chimney...
>

Err... Hang on, what he said is right. If the flame doesn't stay hot as hell
going up the chimney, it will soot up. Be very careful about keeping the
stack clear.

I have a set of long poles with a brush that I use on the stove pipe every
few months to clear out any accumulations. Before I started doing that we
had some "interesting" house warming experiences with the smoke coming back
into the house and flames coming out the stack at night.

---
James.


2007\07\23@172240 by piclist

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face
Hi Russel,

I've done aluminum casting at home before, but I never got around to take
picutres.  I built this little furnace here:

http://www.dansworkshop.com/Homebuilt%20Electric%20Melting%20Furnace.shtml

Although the coils burnt after some use, I modified to work like this
one here:

http://www.atmsite.org/contrib/Sapp/foundry/foundry.html

using a leaf blower.

Basically this will work well for a few parts, but not more.

Disclaimer:  By attempting to replicate what I describe to you below,
you accept
that you are doing so out of your own will and that I am not responsible for
your results, intentinally or not.

Make a base with some fire bricks (1 layer is good enough).  On that
base, make
an octagon with firebricks on their sides (but leave one of the corners open a
little bit (2 to 3 inches), put natural wook charcoal (it burns hot enough for
aluminum, but your off the mill bbq brickets do not) in there, then put a
steel/iron bbq grill over that, then make more octagons on top of of the grill
as to make a little tower high enough for your crucible to fit in, but this
time, close the octagon completely (no gap between 2 of the bricks).

Light up the charcoal, put crucible in, then start up your leaf blower
and point
it into the gap of your first octagon of bricks.

Note, this is going to make lots of little hot ambers fly up, just like those
bonfires when you go camping, but because your blowing a lot of high velocity
air into the fire, you'll have a lot more of them flying out than your regular
camping fire, so don't do this inside the house or any other place you don't
want to set fire to :)

The furnace in the first link works much better than the stack of bricks
obviously, since no air is going to be scaping through the gaps between the
bricks, but for a couple of small parts it works well.

Good luck, and remember to have a water hose nearby ready to go just in case.


-Mario



Quoting Russell McMahon <.....apptechKILLspamspam@spam@paradise.net.nz>:

{Quote hidden}

> -

2007\07\23@215441 by Roger, in Bangkok

face
flavicon
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Pistons are a popular source for aluminum alloy (pistonium) for casting
because it has good machining qualities as well.  Wheelonium (from mag
wheels, of course) is also popular for the same reason.  HOWEVER ...
magnesium is the alloying metal.  ONLY melt it where you have good
temperature control AND a hole where can can dump it quickly should it
decide to catch fire and burn itself in spite of your good temperature
control.  Dumping it in a whole and covering it with sand or dirt will
protect you, the kids and critters, but won't extinguish the fire ... it
generates its own oxygen until all burned up.  A beautiful flame for sure,
just don't get caught off guard!

Any misspellings noted above are clearly the sole fault of M$ corporation's
various spell checker libraries, and in no way the fault or responsibility
of the writer, the moon or the stars :-))

Regards/Roger, in Bangkok

On 7/23/07, Michael Rigby-Jones <Michael.Rigby-JonesspamKILLspambookham.com> wrote:
{Quote hidden}

> >{Original Message removed}

2007\07\25@095302 by Russell McMahon

face
flavicon
face
I've been impressed with the number and quality of the responses re
alumin[i]um casting.
I was very impressed with the two smelter links posted yesterday.
>From the overall material I've seen It seems like a charcoal and leaf
blower and very basic one off furnace solution may suffice.

Comment on the following variation would be welcome.

Zinc melts at substantially below Al's melting point.
I have a modest amount of zinc.

Tin               232 C (too low!!!)
Zinc             419 C
Al                659 C
Brass           900 - 940
Bronze        850 - 1000
Cu              1083 C
Cast Iron    1250 C
Iron            1530 C

Magnesium at 670 C is interesting - but best avoided at present :-).

I could arrange vertical Al fins or rods or whatever in their final
orientation in a steel shell* and then pour in a relatively thin layer
of molten zinc. One outcome would be a zinc layer with Al fins
embedded in it. If poured into a flat bottomed mould that stayed flat
the bottom surface may be OK "as is". Being thermally conductove may
cause problems.

Other outcomes might be - whatever you are going to tell me about this
idea :-).

This systems allows good fin to base thermal connection, solidity of
final design, ease of melting, smaller molten metal requirement, ... .
Disadvantages are ... ?

* The "shell" need not be especially thick or strong or deep. Using a
steel baking tray of suitable area seems like a viable idea. Getting
the zinc out of it afterwards may be an issue. Conceivably an Al oven
liner - effectively just thick foil, should work with zinc and would
not even need to be removed if it happened to bond well. But, I
suspect I may be rather pushing my luck pouring any sort of molten
metal into such a thin container. Embedding it in sand or similar
first may be enough. And may not.



       Russell





2007\07\25@103655 by Rich Satterlee

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face
Hiya-

You mentioned:
"I could arrange vertical Al fins or rods or whatever in their final
orientation in a steel shell* and then pour in a relatively thin layer
of molten zinc."

The Al fins might "float" after the zinc has been poured.  I suggest that you
strongly affix the Al that you use so that it doesn't move around too much
while/after you pour the zinc.

Best of luck!

 Cheers,

   Rich S.

---- Original Message ----
From:                Russell McMahon
Date:                Wed 7/25/07 7:03
To:                PIC List
Subject:        Re: [EE]:: Casting Alumin[i]um

I've been impressed with the number and quality of the responses re
alumin[i]um casting.
I was very impressed with the two smelter links posted yesterday.
>From the overall material I've seen It seems like a charcoal and leaf
blower and very basic one off furnace solution may suffice.

Comment on the following variation would be welcome.

Zinc melts at substantially below Al's melting point.
I have a modest amount of zinc.

Tin               232 C (too low!!!)
Zinc             419 C
Al                659 C
Brass           900 - 940
Bronze        850 - 1000
Cu              1083 C
Cast Iron    1250 C
Iron            1530 C

Magnesium at 670 C is interesting - but best avoided at present :-).

I could arrange vertical Al fins or rods or whatever in their final
orientation in a steel shell* and then pour in a relatively thin layer
of molten zinc. One outcome would be a zinc layer with Al fins
embedded in it. If poured into a flat bottomed mould that stayed flat
the bottom surface may be OK "as is". Being thermally conductove may
cause problems.

Other outcomes might be - whatever you are going to tell me about this
idea :-).

This systems allows good fin to base thermal connection, solidity of
final design, ease of melting, smaller molten metal requirement, ... .
Disadvantages are ... ?

* The "shell" need not be especially thick or strong or deep. Using a
steel baking tray of suitable area seems like a viable idea. Getting
the zinc out of it afterwards may be an issue. Conceivably an Al oven
liner - effectively just thick foil, should work with zinc and would
not even need to be removed if it happened to bond well. But, I
suspect I may be rather pushing my luck pouring any sort of molten
metal into such a thin container. Embedding it in sand or similar
first may be enough. And may not.



       Russell





2007\07\27@055302 by Ian Stewart

flavicon
face
Hi Russell

May be overkill for your purpose but just today saw the Feb/ March
copy of "The Shed" has detailed instructions on how to build your own
furnace. Web page for the Mag. http://www.theshedmag.co.nz

Ian
----- Original Message -----
From: "Russell McMahon" <.....apptechKILLspamspam.....paradise.net.nz>
To: "PIC List" <EraseMEPICLISTspam_OUTspamTakeThisOuTMIT.EDU>
Sent: Thursday, July 26, 2007 1:52 AM
Subject: Re: [EE]:: Casting Alumin[i]um


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