How To Make a Smelter

To All:

It's easy. YOU CAN DO IT.

The basic idea is to line a steel drum or barrel with refractory
material such as fire brick, mortared together with fire-clay, sand
and refractory cement. That will get you a BIG smelter, one you'll
probably NEVER USE.

So start with a SMALLER steel drum. Get yourself a 'boat' --
something in which to mix your refractory CEMENT. You aren't going to
use any fire brick... except mebbe for the bottom.

You want the bottom to be about two inches thick and solid refractory
material. Pumping up a good flame, the temperature will approach
three thousand degrees Fahrenheit. And that is one hell of a fire,
pard.

Get yourself some CARDBOARD. Quite a bit of it. You are going to
ROLL the cardboard until it has the OD that you want. The OD must
match the OD of your CRUCIBLE plus about two inches per side. So go
find yourself a crucible. But keep in mind, if you're smelting
aluminum you DON'T want it in contact with any iron or steel. It will
be 'poisoned' and turn out brittle (!) (Yeah, I didn't think so
either. Trust me, it'll crack like glass.) Now you CAN use iron or
steel... so long as you DIP your crucible in a refractory COATING
before you charge it with lumps of aluminum. Just mix up the
refractory coating about the same as pan-cake mix, then dip the pot in
it, let it drain, then dry, the BAKE to cure it. All cured? Then dip
it again. In fact, dip it about three times. Last time is the
charmer. Make sure it has no cracks and that you haven't scraped
through the dip at any point. Now you can bake it. Pretend it's just
another piece of ceramic art. It won't be, because you'll have a
couple of tangs stick out through it which you have CLEANED OFF every
time you've dipped it. Then put it in the furnace to bake. Patience
is your pal. Go do something else whilst baking your refractory mix.

What's a good mix? I used fire-clay and a patent 'refractory cement'
-- some black sh.... stuff that you mix with water. I added fire-clay
to that and ended up with a thick, grey slurry. I dipped and let it
air-dry twice, then threw some charcoal into the furnace, light it
off, got the charcoal going good then propped the crucible over the
coals. I didn't pay a lot of attention to the inside of the
crucible. It was a solid, seamless coating. I made the pot out of
steel tubing 4.5" in diameter and about 9" high. The bottom was a
piece of 3/8" thick steel plate, MIG'ged to the pipe. I cut a couple
of bolts down to 1" length measured from under the head. I made two
sets of tongs, one to lift the crucible in & out of the furnace (lid
is off, the thing will flat FRY you unless you are protected by at
least two layers of leather... and more is better). Furnace has a 2"
hole in the side down low; lid has a 2" hole in the middle (was a tin
can until I poured in the refractory stuff, mixed with lotsa fire-clay
and #80 silicon sand.

You see some guys using tongs six feet long and you laugh. Don't.
Not until you've had a pot full of molten metal in your grip.

You got goodd shoes? And I'm not talking K-Mart. Good LEATHER
shoes. Plus leather OVER them to act like a rain shield, in case you
slip and spill a little.

Once you pull the pot out of the furnance you'd damn well better know
what comes next... you can't stand there hold it with one hand while
scratching your ass, trying to figure out what to do.

Mine, I gotta sit it down. So I have a Sitting Down Place.
Concrete. Dry. Pouring Tongs just beside it. Sit down the crucible,
pick up the Pouring Tongs, pick up the crucible, move mebbe six
inches... prolly less, there's the flask, ready & waiting. Pour.

Hell of a note.. Steam. Smoke. Fumes. Flames. You're inside of it
all, standing there, pouring. Nice & steady. Pouring. That's your
job. Pour the molten metal outta the pot into the flask. Pouring.
At just the right speed. Fill it right up. Fill up the mold and the
tower and the top of the flask. And you'd better have made damn sure
you got enough metal to fill the mold.

All done? Okay, swing the crucible over HERE and pour any excess into
those ingot molds. Shouldn't have any excess but some is better than
none. Now swing the crucible BACK to the Sitting Down Place. Sit it
down. Put down the Pouring Tongs, pick up the Lifting Tongs, put the
crucible back into the furnace. Close the lid. Now you can think
about other things.

Lemme give you a hint. If you've never cast nothing in your life
before, DON'T start with this. Start by casting some fish weights
outta wheel balance weights. Start with casting balls for your cap &
ball rifle. Start with anything OTHER than a bucket fulla aluminum.
Because there's a lot of little details that can scar you for life.
And you only get the one chance to learn... that FIRST time. It helps
if you got someone there who'se done it before, kinda breathing down
your neck.

FIRST time, do something EASY. Rudder pedals. "VP-II" cast right
into them suckers!

-R.S.Hoover

On Sun, 25 Jan 2009 18:36:27 -0800 (PST), "
wrote:

To All:

It's easy. YOU CAN DO IT.

The basic idea is to line a steel drum or barrel with refractory
material such as fire brick, mortared together with fire-clay, sand
and refractory cement. That will get you a BIG smelter, one you'll
probably NEVER USE.

So start with a SMALLER steel drum. Get yourself a 'boat' --
something in which to mix your refractory CEMENT. You aren't going to
use any fire brick... except mebbe for the bottom.

snip

All done? Okay, swing the crucible over HERE and pour any excess into
those ingot molds. Shouldn't have any excess but some is better than
none. Now swing the crucible BACK to the Sitting Down Place. Sit it
down. Put down the Pouring Tongs, pick up the Lifting Tongs, put the
crucible back into the furnace. Close the lid. Now you can think
about other things.

Lemme give you a hint. If you've never cast nothing in your life
before, DON'T start with this. Start by casting some fish weights
outta wheel balance weights. Start with casting balls for your cap &
ball rifle. Start with anything OTHER than a bucket fulla aluminum.
Because there's a lot of little details that can scar you for life.
And you only get the one chance to learn... that FIRST time. It helps
if you got someone there who'se done it before, kinda breathing down
your neck.

FIRST time, do something EASY. Rudder pedals. "VP-II" cast right
into them suckers!

-R.S.Hoover

two points, I'm not even going to touch on burners.

B. Terry Aspin wrote a book on home foundry work. it is available
through the Model Engineer sources in England. Very good reference for
someone thinking about this.
a suggestion that terry made in model engineer that has saved my
bacon.
eventually you will break a crucible. they come out of the furnace
between white hot and very cherry red depending on what you are
melting. they are in the plastic range for strength and when one goes
it often goes slowly just with an inexorable tearing.

for just these moments you need a few of terry's sand trays. at least
one every pour.
they are done in galv sheet steel and are about 18" square. you bend
up about 2" around each side to about 45 degrees and braze the
corners. into your emergency tray goes the driest of driest sands to
about an inch or so depth. in the sand you make swirl marks with your
fingers.

when you have the realisation that a crucible is letting go you place
it in the sand tray, or you pour it out in the sand tray.
that tray is the only dry safe place that you can dump the molten
metal.
if you drop it onto the ground any moisture that is present will flash
to steam instantly and explode the molten metal into a hand grenade.

I use a salamander crucible usually. In australia they also make a
fireclay crucible that is a single use item in the gold assay
industry. they are just a couple of dollars - cheap as chips. I have
used one for 18 months on a regular basis doing aluminium castings.
when one of these guys gets damaged and starts to come apart Terry's
sand trays are worth gold.

hydrogen embrittlement was a big bogey man in home castings but it is
easily understood and conquered.
just as salts dissociate in water to become their component ions water
itself seems to do the same sort of thing in aluminium. the hydrogen
can be absorbed by the molten aluminium in amazing quantities, the
oxygen becoming oxide dross on the surface of the mix.
cooled solid aluminium has no ability to hold hydrogen and it comes
out of solution in bubbles through the metal.

the ways to conquer this: make sure all the metal you melt is bone
dry. cast on low humidity days. if you notice lots of dross coming to
the surface you should purge the mix with an aluminium chloride tablet
plunged to the base of the crucible in a stainless steel wire cage.
this also dissociates in the molten metal and the aluminuim joins the
pour. the chlorine bubbles up combining with the hydrogen to vent off
as hydrogen chloride gas. if you get a wiff of this it is unbelievably
pungent and combines with moisture in your nose etc to become
hydrochloric acid. it does however do an incredibly good job of
purging the hydrogen gas from the mix.

ok two points done.

this one is a freebie. if you find that you need to make a metal mould
to get the fine fin detail, a cheap as chips mould release is as close
as a wax candle. light the candle and play the flame over the inside
of the metal mould and coat it all in soot. I've only used small metal
molds for model engines but I've never had the aluminium ever get
through the soot release to bond with the mold.
I'm sure veedubber will appreciate the sheer economy of that tip.

Stealth pilot

Those two:

Foundrywork for the Amateur
B.Terry Aspin
WORKSHOP PRACTICE SERIES 4
Argus Books 1984
ISBN 0 85242 842 1

The Charcoal Foundry
David. J. Gingery
ISBN 1 878087 002


KH

Karl-Heinz Künzel schrieb:
Those two:

Foundrywork for the Amateur
B.Terry Aspin
WORKSHOP PRACTICE SERIES 4
Argus Books 1984
ISBN 0 85242 842 1

The Charcoal Foundry
David. J. Gingery
ISBN 1 878087 002


KH

Maybe a 3.rd one

The complete handbook of sand casting
A do-it-yourself guide to forming all types of metal in versatile sand
molds.

C.W.Ammen
TAB BOOKS
ISBN 0 8306 9841 8

That author also published

- The Metalcaster's Bible

- Casting Brass

- Casting Aluminum

KH

On Mon, 26 Jan 2009 14:25:43 +0100, Karl-Heinz Künzel
wrote:

Karl-Heinz Künzel schrieb:
Those two:

Foundrywork for the Amateur
B.Terry Aspin
WORKSHOP PRACTICE SERIES 4
Argus Books 1984
ISBN 0 85242 842 1

The Charcoal Foundry
David. J. Gingery
ISBN 1 878087 002


KH

Maybe a 3.rd one

The complete handbook of sand casting
A do-it-yourself guide to forming all types of metal in versatile sand
molds.

C.W.Ammen
TAB BOOKS
ISBN 0 8306 9841 8

That author also published

- The Metalcaster's Bible

- Casting Brass

- Casting Aluminum

KH

aspin and ammen are the good ones.

On Jan 27, 12:39*am, Stealth Pilot
wrote:

aspin and ammen are the good ones.
-----------------------------------------------------------------------------------------------------------
Roger that. But if you Google Aspin you'll find it available (via
Amazon) in Japan, France and the UK... but not in the USA. :-)

-Bob

PS -- Big Day for the Doc Shop today. (I surely wish they'd warm
up them IV's. Definitely a chilling experience.

Stealth Pilot wrote:
.....
when you have the realisation that a crucible is letting go, you place
it in the sand tray, or you pour it out in the sand tray.
that tray is the only dry safe place that you can dump the molten
metal....
Stealth pilot

You might think that a puddle of lead on the concrete garage floor could
hardly do much harm. After a concrete chip whistles past your ear, you
think again.

Brian W

"Stealth Pilot" wrote

hydrogen embrittlement was a big bogey man in home castings but it is
easily understood and conquered.

OK, I understand hydrogen embrittlement is a "bad thing" but my question
is, where does it come from, start, or what do you do to prevent it from
happening in the first place. I did like your hints for dealing with it,
and can definitely relate on the hydrochloric acid in the nose bit. Also to
be considered one of the "bad things." g
--
Jim in NC

On Jan 27, 2:47*pm, "Morgans" wrote:
"Stealth Pilot" wrote

*but my question
is, where does it come from, start, or what do you do to prevent it from
happening in the first place. *I did like your hints for dealing with it,
Jim in NC

Where does it come from? There is hydrogen all around when casting.
Comes from the propane(butane) burned to make the heat, from that oily
piston tossed into the fire, even the mayo on your hands from lunch.
I suspect those cooking with charcoal actually have less problems than
casters using the "cleaner" fuels.

What to do about it? Clean metal and some degas agent. When I melt
pistons and other salvage I never use it in the virgin state. Cast
some biscuits in your ingot molds and let cool. Then they are ready
to use, and in nice little chunks too :-) Toss in a little salt and
sidewalk de-icer, don't keep peeking at the pot, and you should be
good to go for the real parts.

Works for me. I've never noticed any problems with my castings, but
that doesn't mean there aren't some....................
===================
Leon McAtee

On Tue, 27 Jan 2009 16:47:51 -0500, "Morgans"
wrote:


"Stealth Pilot" wrote

hydrogen embrittlement was a big bogey man in home castings but it is
easily understood and conquered.

OK, I understand hydrogen embrittlement is a "bad thing" but my question
is, where does it come from, start, or what do you do to prevent it from
happening in the first place. I did like your hints for dealing with it,
and can definitely relate on the hydrochloric acid in the nose bit. Also to
be considered one of the "bad things." g

I'm not an industrial chemist. this comes from watching what happens
in my castings and reading some of the references mentioned.

I first twigged to what may be happening when I grabbed some pistons
that had been sitting outside and plopped them into the part filled
crucible to get the volume up for a pour. they were damp.
I thought a furnace at many hundreds of degrees would dry the stuff
pretty well instantly.
the casting turned out to be like aluminium foam. first time it had
happened to me.
the possible explanation is that the water didnt evaporate but
dissolved into the molten aluminium.
what points me to this is another oddity.
you would think that copper with a melting point of 1500 degrees would
be difficult to incorporate in aluminium which is only at 360 degrees
or so but it isnt so. stir the mix with a copper tube or rod and the
rod will absorb readily into the molten aluminium.

I think that the same thing occurs with water believe it or not.
the fluid appears to dissociate into its component parts in the molten
aluminium.
the oxygen causes lots of oxide froth on the top of the crucible.
the hydrogen remains as a dissolved gas until the aluminium starts to
solidify whereupon it comes out of suspension as bubbles.

where does it come from? any source of moisture that gets to the
molten metal. wet or damp oxide coated stuff that you are recycling
has done it to me. personally I've never found it related to humidity
in the air but Mr Ammen mentions it.

the easiest way I've found of preventing it is to store the scrap
inside and keep it clean and dry. melting clean dry stuff has always
resulted in sound castings for me.

It is a pity the hydrogen bubbles formed on cooling couldnt be
controlled because the foam aluminium is quite light. you just cant
control where the bubbles form and thus the structural integrity.

Stealth Pilot