How To Make a Smelter

On Jan 25, 9:36*pm, " wrote:
...

Mine, I gotta sit it down. *So I have a Sitting Down Place.
Concrete. *Dry. *...


I cringed when I read this. Concrete isn't dry. There is always
water retained in the matrix. Heated, it can flash into steam and
explode small chips of concrete and whatever it was that was
hot enough to explode it up into the air.

It is best to use dry sand. If you can, heat it before each use to
make sure it is dry.

And between uses keep it covered as you never know when
a cat is going to come by.

"Fred the Red Shirt" wrote in message
...
On Jan 25, 9:36 pm, " wrote:
...

Mine, I gotta sit it down. So I have a Sitting Down Place.
Concrete. Dry. ...


I cringed when I read this. Concrete isn't dry. There is always
water retained in the matrix. Heated, it can flash into steam and
explode small chips of concrete and whatever it was that was
hot enough to explode it up into the air.

It is best to use dry sand. If you can, heat it before each use to
make sure it is dry.

And between uses keep it covered as you never know when
a cat is going to come by.

-----------------------------------------------------------------------------------------------------

You're right about concrete, but with the low melt temp of aluminum, 20 to
30 pounds of aluminum on a floor at least 2 or 3 years or so old is not a
big deal. But concrete 3 to 6 months old, or higher temp metals can be real
exciting.

Sand, because it is loose and permeable, can contain 3 to 5% moisture with
no problems at all. As much a 5% is often used for molding.

Maxwell wrote:
"Fred the Red Shirt" wrote in message
...
On Jan 25, 9:36 pm, " wrote:
...

Mine, I gotta sit it down. So I have a Sitting Down Place.
Concrete. Dry. ...


I cringed when I read this. Concrete isn't dry. There is always
water retained in the matrix. Heated, it can flash into steam and
explode small chips of concrete and whatever it was that was
hot enough to explode it up into the air.

It is best to use dry sand. If you can, heat it before each use to
make sure it is dry.

And between uses keep it covered as you never know when
a cat is going to come by.

-----------------------------------------------------------------------------------------------------

You're right about concrete, but with the low melt temp of aluminum, 20 to
30 pounds of aluminum on a floor at least 2 or 3 years or so old is not a
big deal. But concrete 3 to 6 months old, or higher temp metals can be real
exciting.

Sand, because it is loose and permeable, can contain 3 to 5% moisture with
no problems at all. As much a 5% is often used for molding.


Beg to disagree with you , but concrete which was cured properly ( kept covered

or sprayed with water, so that the water can chemicaly combine with
the materials
in the cement ) has considerable moisture in it known as "water of
hydration."--This bond can be broken with the application of heat.--I
watched an asphalt storage building burn---the melted asphalt would run
out on the floor and burn for a while, until POW! a large piece of the
floor would explode flinging concrete & burning asphalt 10 or 20 ft
away.---the floor was at least 20 years old or so..Poorly cured concrete
still has some water bound up in it, maybe not as much--but it is not as
strong as that which was properly cured.

"Jerry Wass" wrote in message
.. .


You're right about concrete, but with the low melt temp of aluminum, 20
to 30 pounds of aluminum on a floor at least 2 or 3 years or so old is
not a big deal. But concrete 3 to 6 months old, or higher temp metals can
be real exciting.

Sand, because it is loose and permeable, can contain 3 to 5% moisture
with no problems at all. As much a 5% is often used for molding.

Beg to disagree with you , but concrete which was cured properly ( kept
covered

or sprayed with water, so that the water can chemicaly combine with the
materials
in the cement ) has considerable moisture in it known as "water of
hydration."--This bond can be broken with the application of heat.--I
watched an asphalt storage building burn---the melted asphalt would run
out on the floor and burn for a while, until POW! a large piece of the
floor would explode flinging concrete & burning asphalt 10 or 20 ft
away.---the floor was at least 20 years old or so..Poorly cured concrete
still has some water bound up in it, maybe not as much--but it is not as
strong as that which was properly cured.


I think you misunderstood Jerry, I agreed he was right about the hazard of
heat and concrete. My example was from personal experience. Spilling 200 to
300 cubic inches of 1400 degree aluminum, on a concrete floor more than a
few years old, is not usually a really big deal. Uncontained, it will spread
and quickly cool by 50% in a matter of seconds.

In your example, obviously more than 1400 degrees, with an exposure time of
many minutes, it can be a really big deal indeed. No matter how old the
concrete.

Maxwell wrote:
"Jerry Wass" wrote in message
.. .

You're right about concrete, but with the low melt temp of aluminum, 20
to 30 pounds of aluminum on a floor at least 2 or 3 years or so old is
not a big deal. But concrete 3 to 6 months old, or higher temp metals can
be real exciting.

Sand, because it is loose and permeable, can contain 3 to 5% moisture
with no problems at all. As much a 5% is often used for molding.

Beg to disagree with you , but concrete which was cured properly ( kept
covered
or sprayed with water, so that the water can chemicaly combine with the
materials
in the cement ) has considerable moisture in it known as "water of
hydration."--This bond can be broken with the application of heat.--I
watched an asphalt storage building burn---the melted asphalt would run
out on the floor and burn for a while, until POW! a large piece of the
floor would explode flinging concrete & burning asphalt 10 or 20 ft
away.---the floor was at least 20 years old or so..Poorly cured concrete
still has some water bound up in it, maybe not as much--but it is not as
strong as that which was properly cured.

I think you misunderstood Jerry, I agreed he was right about the hazard of
heat and concrete. My example was from personal experience. Spilling 200 to
300 cubic inches of 1400 degree aluminum, on a concrete floor more than a
few years old, is not usually a really big deal. Uncontained, it will spread
and quickly cool by 50% in a matter of seconds.

In your example, obviously more than 1400 degrees, with an exposure time of
many minutes, it can be a really big deal indeed. No matter how old the
concrete.


You sooo right---Ya Know, the reader usually puts more into the statement than
the writer intended..

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

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


What you are describing is not Hydrogen Embrittlement. Hydrogen
Embrittlement is usually more of an issue for high carbon steels I
believe, though it effects aluminum as well. You can find information
on it under the heading of stress corrosion cracking and it is more of
an environmental issue than casting, as it is a problem for forgings and
weldments as well. It is the mechanism of failure I am pretty sure for
the old VW cases, as magnesium alloys are very susceptable to SCC.

Your description of the problem of the casting problem though is spot
on, if misnamed. Here is a good link on this and other alumminum
casting issues:

http://www.keytometals.com/Article83.htm

Charles

"Charles Vincent" wrote in message
...
Stealth Pilot wrote:
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'm not an industrial chemist. this comes from watching what happens
in my castings and reading some of the references mentioned.


What you are describing is not Hydrogen Embrittlement. Hydrogen
Embrittlement is usually more of an issue for high carbon steels I
believe, though it effects aluminum as well. You can find information on
it under the heading of stress corrosion cracking and it is more of an
environmental issue than casting, as it is a problem for forgings and
weldments as well. It is the mechanism of failure I am pretty sure for
the old VW cases, as magnesium alloys are very susceptable to SCC.

Your description of the problem of the casting problem though is spot on,
if misnamed. Here is a good link on this and other alumminum casting
issues:

http://www.keytometals.com/Article83.htm

Charles

Actually it highlights his misunderstanding of the process. In an effort to
look like he knows something about casting, he began searching the internet
and found reams of confusing material discussing hydrogen embrittlement, and
confused it with hydrogen absorption.

Nice link, by the way, it at least begins to discuss the difficulties of
pouring quality molten aluminum, especially in low volumes if you read
between the lines.

Saying you are going to pour a quality casting from melting old pistons, in
a steel pot, with a propane yard burner - is much like saying you are going
to grind you own crankshaft with a modified wood lathe and a hand grinder.

Maxwell wrote:


Actually it highlights his misunderstanding of the process. In an effort to
look like he knows something about casting, he began searching the internet
and found reams of confusing material discussing hydrogen embrittlement, and
confused it with hydrogen absorption.

Nice link, by the way, it at least begins to discuss the difficulties of
pouring quality molten aluminum, especially in low volumes if you read
between the lines.

Saying you are going to pour a quality casting from melting old pistons, in
a steel pot, with a propane yard burner - is much like saying you are going
to grind you own crankshaft with a modified wood lathe and a hand grinder.



It highlights his misunderstanding of the nomenclature, nothing more.
Not unusual when someone is self taught, especially via trial and error.
I work in a highly technical field and am still plagued by
pronunciations that I assigned to unfamiliar technical terms in my self
study over thirty years ago.
As far as getting quality castings out of a home shop, it takes the same
two things in the home shop as in production. A quality repeatable
process appropriate to the end results desired and essentially a
statistical testing process. Both could be achieved in the home shop,
but will require the casting not of just four heads, but more likely
four hundred castings, with the majority hitting the scrap bin. I
think Veedubers current tack is better alternative.

Charles

"Charles Vincent" wrote in message
news
Maxwell wrote:


Actually it highlights his misunderstanding of the process. In an effort
to look like he knows something about casting, he began searching the
internet and found reams of confusing material discussing hydrogen
embrittlement, and confused it with hydrogen absorption.

Nice link, by the way, it at least begins to discuss the difficulties of
pouring quality molten aluminum, especially in low volumes if you read
between the lines.

Saying you are going to pour a quality casting from melting old pistons,
in a steel pot, with a propane yard burner - is much like saying you are
going to grind you own crankshaft with a modified wood lathe and a hand
grinder.



It highlights his misunderstanding of the nomenclature, nothing more. Not
unusual when someone is self taught, especially via trial and error. I
work in a highly technical field and am still plagued by pronunciations
that I assigned to unfamiliar technical terms in my self study over thirty
years ago.

Not really. The overwelming issue with hydrogen absorbtion in molten
aluminum is gas porosity, not embrittlement.


As far as getting quality castings out of a home shop, it takes the same
two things in the home shop as in production. A quality repeatable
process appropriate to the end results desired and essentially a
statistical testing process. Both could be achieved in the home shop, but
will require the casting not of just four heads, but more likely four
hundred castings, with the majority hitting the scrap bin. I think
Veedubers current tack is better alternative.

Not true at all.