Rocket Man VW Heads... What alloy?

On Sat, 10 Jan 2009 11:15:40 -0800 (PST), "
wrote:

356-T6 is usually selected for its HIGH STRENGTH rather than its
ability to pass heat

While I don't disagree with you, my ASME Metals Properties (1954)
shows the 356 alloy to be well above average in thermal conductivity.
What alloy is usually used in aluminum heads?

George

On Jan 12, 7:17*am, GeorgeB wrote:
What alloy is usually used in aluminum heads?
--------------------------------------------------------------------------------

I don't know, George. My data is probably out of date. The Navy code
is (or was) MM212a... which I was told is equal to A.S.T.M. B26-37T ,
cited as suitable for Aluminum Sand Castings (Cylinder Heads,
Crankcases, Etc.) It has 4% copper and has about the same thermal
conductivity of the other copper-bearing alloys ( ie,
0.0000125 ...meaning that's it's coefficient of expansion between 68
and 392*F ). Not very strong, though... 32kpsi (Tension)
-------------------------------------------------------------------------------------------------------------

While I don't disagree with you, my ASME Metals Properties (1954)
shows the 356 alloy to be well above average in thermal conductivity.

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

It's okay to disagree with me, George :-) I'm just whipping most of
these numbers out of my ass anyway. When I was the leading Chief at
COMCRUDESPAC's computer shop we were just across the street from the
Pattern-makers school at the 32st Naval Station, and me & the Chiefs
over there were about the only Chiefs for some distance around, so we
were always bumping into each other. I picked up a little bit of
knowledge about casting & pattern making. Enough at least, to cast
little do-dads. Our local junior high usta teach that; showing kids
how to make ash trays and the like. All gone now, of course. Too
dangerous or something.

But it doesn't really matter. Because I'll be using old pistons any
way :-)

It's not a question of strength, money nor physical properties, but
more a question of time & convenience. With about a thousand people
'subscribed' to this group, and everyone TALKING about the subject,
odds are I'll be the only one to actually DO anything about it :-)

Pretty exclusive club, Doing Things.

My muller (the thing that you use to mix the oil or what-have-you with
the sand) is one of those humongous mixers you drive with a 1/2" drill
motor (usually used to mix mortor). I use #100 sand from Dixieline
Lumber in Escondido... costs about two bucks a bag (or did). I've got
several flasks around the place, plus a small furnace that uses a weed-
eater flame nozzle. My 'furnace' is a big bucket lined with fire-
clay. Steel pot for the melting. Dipped in a slurry of refractory
material, allowed to dry then 'cooked' in the furnance until it's
cheery red and allowed to cool. The aluminum gets heated then chunked
up with a BIG iron bar. Anything left over goes into a couple of
steel molds.

The tricky bit is making the patterns. I think I've got it figured
out but I haven't tried making the core boxes as yet.

To make cores I use some molasses and paste-flour, plus a bit of
water. #100 sand. Pack it good & tight then dismantle the core-box
and hope it don't crack. Put them in the over to cook overnight @ 250
degrees. Next morning (or eight hours later) you've got a light --
hopefully porous -- core that will fit the holes in your pattern.
High tech it ain't :-)

-Bob

"Stealth Pilot" wrote in message
...
On Sat, 10 Jan 2009 14:11:47 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:



--------------------------------------------------------------------------
What do you use for sand and binder? How do you mix?


you can make your own greensand.

basically you get some buckets of sand. plonk a gently running hose
into the bucket and let it float off everything but the sand.
keep the hose running until the water coming off is clear. this gets
rid of crap and non bentonite clays.

find or buy some bentonite clay.
you can buy sodium modified bentonite in 25lb bags.
you need bentonite clay because of its peculiar charactersitics. it is
different from all the other clays and the difference is what makes it
useful in casting.

ok let your washed sand dry off a bit.
weigh the sand and mix in 5% thereabouts by weight of bentonite.
this is the important bit; you need to put a coating of bentonite
around each sand particle. you dig your clean hands into the sand and
bentonite and with a handfull between your hands you run them back and
forth to work a coating of clay around each sand particle.
(your hands end up really smooth from this)

ok now you let your mix dry right out. this can take a week.

when you want to use the greensand you mix in 5% of water by weight
and nead the greensand so that it is uniformly wet out.

if you pat up a sausage out of it about 2" dia and a foot long you
should be able to hold this by an end and wave it all over the place
and none of the sand will part company.

you then need to do some test pours to see if the porosity of your
greensand means it is too coarse.

if you can handle that intelligently I'll go on to tell you why most
people get their furnaces wrong and what you need to do to get it
right.
Stealth Pilot

What's the point? If you are going to buy bentonite, why not buy a quality
molding sand like silica or olivine as well?

At any rate, good luck on your green strength test. Even the finest seasoned
and mix green sand will in no way meet the expectation of your 2" x 12"
sample as stated.

wrote in message
...
On Jan 12, 7:17 am, GeorgeB wrote:
What alloy is usually used in aluminum heads?
--------------------------------------------------------------------------------

I don't know, George. My data is probably out of date. The Navy code
is (or was) MM212a... which I was told is equal to A.S.T.M. B26-37T ,
cited as suitable for Aluminum Sand Castings (Cylinder Heads,
Crankcases, Etc.) It has 4% copper and has about the same thermal
conductivity of the other copper-bearing alloys ( ie,
0.0000125 ...meaning that's it's coefficient of expansion between 68
and 392*F ). Not very strong, though... 32kpsi (Tension)
-------------------------------------------------------------------------------------------------------------

While I don't disagree with you, my ASME Metals Properties (1954)
shows the 356 alloy to be well above average in thermal conductivity.

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

It's okay to disagree with me, George :-) I'm just whipping most of
these numbers out of my ass anyway. When I was the leading Chief at
COMCRUDESPAC's computer shop we were just across the street from the
Pattern-makers school at the 32st Naval Station, and me & the Chiefs
over there were about the only Chiefs for some distance around, so we
were always bumping into each other. I picked up a little bit of
knowledge about casting & pattern making. Enough at least, to cast
little do-dads. Our local junior high usta teach that; showing kids
how to make ash trays and the like. All gone now, of course. Too
dangerous or something.

But it doesn't really matter. Because I'll be using old pistons any
way :-)

It's not a question of strength, money nor physical properties, but
more a question of time & convenience. With about a thousand people
'subscribed' to this group, and everyone TALKING about the subject,
odds are I'll be the only one to actually DO anything about it :-)

Pretty exclusive club, Doing Things.

My muller (the thing that you use to mix the oil or what-have-you with
the sand) is one of those humongous mixers you drive with a 1/2" drill
motor (usually used to mix mortor). I use #100 sand from Dixieline
Lumber in Escondido... costs about two bucks a bag (or did). I've got
several flasks around the place, plus a small furnace that uses a weed-
eater flame nozzle. My 'furnace' is a big bucket lined with fire-
clay. Steel pot for the melting. Dipped in a slurry of refractory
material, allowed to dry then 'cooked' in the furnance until it's
cheery red and allowed to cool. The aluminum gets heated then chunked
up with a BIG iron bar. Anything left over goes into a couple of
steel molds.

The tricky bit is making the patterns. I think I've got it figured
out but I haven't tried making the core boxes as yet.

To make cores I use some molasses and paste-flour, plus a bit of
water. #100 sand. Pack it good & tight then dismantle the core-box
and hope it don't crack. Put them in the over to cook overnight @ 250
degrees. Next morning (or eight hours later) you've got a light --
hopefully porous -- core that will fit the holes in your pattern.
High tech it ain't :-)

-Bob

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

First, I would recommend you double check your source on sand. Most building
supply folks sell "river" sand. If you examine it closely, you will find it
is made up of round granules that look simply like pea gravel. Silica sand,
the white sand used for years in public ash trays and some blasting
operations is much more suitable, and well worth the addtional cost. Olivine
is also very popular for green sand molding, although it cost a good bit
more. The shape of these sands are much more irregular, and thus will form
much stronger molds regardless of which binder you choose.
http://en.wikipedia.org/wiki/Olivine

I'm not familiur with your binder recipe, but might want to try a sodium
silicate based solution to simplify your process. You can mix a one part
liquid with your sand, ram up your core boxes, and simply gas them with CO2
gas to set them in less than 60 seconds. There are also catalists available
that will cure them in 10 minutes or so, if you have a mixing process that
allows you to mix the sand and get it in the mold that quickly. I have
friends in the business and could probably get you a gallon sample freebe if
you would like to try it. I'm told it's about $75 for 5 gallons if you get
addicted to it, but it only takes about 2% if you have a good mixing
process.

As for the metal and the melt process, to each his own. But I can say from
experience you stand a good chance of having porosity problems with the
method you discribe, and there are cheaper ways to do things. Having the
ability to fabricate the patterns are the real challange here, and I have no
doubt you can do that. Once they are complete, a small shop could probably
cast you some heads for less than your time and supplies are worth.

There is also the possibility of molding this in plaster, but that's another
story.

On Jan 12, 8:38*pm, "Maxwell" #$$9#@%%%.^^^ wrote:
-----------------------------------------------------------------------------------------------------

First, I would recommend you double check your source on sand.
------------------------------------------------------------

BT, DT (big Smiley)
This is good quality 100% silica. They don't even store it in the
same shed, to prevent errors (They'll load stuff for you.).

I've got a couple of bags of #80 but I've found it's a bit too
coarse. (But works fine in the blast cabinet.)

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

I'm not familiur with your binder recipe,

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

I may not be either :-) I think I used 'Karo Syrup' the last time I
made cores but I had a rather unfortunate accident with the
materials. We have cats and... perhaps that's enough said :-)

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

but might want to try a sodium
silicate based solution to simplify your process. You can mix a one part

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

I've seen this used to make some brass castings, literally while the
'customer' was waiting (circa 1975) I've always wanted to try it but
applying the gas makes it appear rather complicated. Of course, guys
who HAVE used it tend to make it sound like mother's milk, whereas
guys who have TRIED to use it make it sound like WWIII. I assume
it's somewhere in the middle :-)

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

. I'm told it's about $75 for 5 gallons

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

Then it's beyond my means. (The cancer has attacked my pocket-book
with even more success than my spine :-)

And besides, I still have the patterns to finish and prove. The last
time I worked with fins I had a HELL of a time before I got the patten
to 'rap' free. Indeed, it made cores simple by comparison.

I will also have to develop the procedure for afixing the valve seats,
hopefully like Stephen.... what's-his-name... the fellow who did so
well racing the Type IV's. His foreman let me try my hand swaging the
seats into a modified Type IV head and that puppy was HOT -- it came
right out of the oven. (Do it COLD -- which was VW's recommended
procedure -- and you'd end up with a loose seat for sure.) Plus the
racer's seats were something like 5/8" deep; VW's appeared to be less
than 1/2". So there's a bit of tooling needed on the production side,
assuming I can get the thing to give me some fins.

....but you've got me thinking about using the CO2 method for the outer
mold as well. Give me another hundred years... or even ONE :-)
--------------------------------------------------------------------------

There is also the possibility of molding this in plaster, but that's another
story.
---------------------------------------------------------------------------

I think I mentioned the dentist. He was casting some exotic STEEL
alloys for bridge-work using the lost-wax process. Had a little
centrifuge, tiny ceramic crucibles -- the whole nine yards but in
miniature. He let us use his oven to heat-treat the hinges for the
Varieze. But only once :-) When I tipped the tray of hinges into the
ice water it drove everyone out of the lab. I guess he'd never seen
it done before.

-Bob

On Mon, 12 Jan 2009 22:04:43 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:


"Stealth Pilot" wrote in message
.. .
On Sat, 10 Jan 2009 14:11:47 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:



--------------------------------------------------------------------------
What do you use for sand and binder? How do you mix?


you can make your own greensand.

basically you get some buckets of sand. plonk a gently running hose
into the bucket and let it float off everything but the sand.
keep the hose running until the water coming off is clear. this gets
rid of crap and non bentonite clays.

find or buy some bentonite clay.
you can buy sodium modified bentonite in 25lb bags.
you need bentonite clay because of its peculiar charactersitics. it is
different from all the other clays and the difference is what makes it
useful in casting.

ok let your washed sand dry off a bit.
weigh the sand and mix in 5% thereabouts by weight of bentonite.
this is the important bit; you need to put a coating of bentonite
around each sand particle. you dig your clean hands into the sand and
bentonite and with a handfull between your hands you run them back and
forth to work a coating of clay around each sand particle.
(your hands end up really smooth from this)

ok now you let your mix dry right out. this can take a week.

when you want to use the greensand you mix in 5% of water by weight
and nead the greensand so that it is uniformly wet out.

if you pat up a sausage out of it about 2" dia and a foot long you
should be able to hold this by an end and wave it all over the place
and none of the sand will part company.

you then need to do some test pours to see if the porosity of your
greensand means it is too coarse.

if you can handle that intelligently I'll go on to tell you why most
people get their furnaces wrong and what you need to do to get it
right.
Stealth Pilot

What's the point? If you are going to buy bentonite, why not buy a quality
molding sand like silica or olivine as well?

At any rate, good luck on your green strength test. Even the finest seasoned
and mix green sand will in no way meet the expectation of your 2" x 12"
sample as stated.


rubbish.
I *actually* do castings.
the shake test is one I can demonstrate in 5 minutes with two
handfulls of greensand from the black bin in my workshop.
I'm writing from first hand experience.

can I suggest you get off your arse and *do* something in life.
your pleasure would increase immeasurably.

Stealth Pilot

On Mon, 12 Jan 2009 22:38:54 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:



There is also the possibility of molding this in plaster, but that's another
story.


unless you've tried it you would have no idea how dangerous that
suggestion actually is.

firstly the strength of plaster vanishes to nothing beyond a certain
temperature. that temperature is just 5 degrees celcius above the
melting point of aloominum.

I have tried the technique to cast a mills 0.75cc diesel crankcase.
this is a tiny thing about an inch and half by an inch and a half in
overall dimensions. relatively tiny and easy to work with.
it was done lost wax.
a day after the plaster was set the mold went into the oven to melt
out the wax. it was then cooked up to about 180 degrees farenheit for
a while (2 hours afaik) to evaporate off the moisture. it stayed in
the oven overnight (I've never been allowed to use the oven again) it
was then given 15 minutes in the microwave to really dry it out.
it was wrapped in a cloth and raced out to the workshop hot.

it looked alabaster white and as dry as a piece of chalk.

when the aluminium was poured into the mold a guyser of molten
aluminium ejected to the ceiling of the workshop. this seemed to
continue for some time. an examination of the mould later showed it to
be totally empty. I dont know how dry you need to get it but I gave it
a fair go at getting a bone dry mould.

I have to ask you what your experience is in casting.
have you ever done any of this yourself or is it something you've
watched?

Stealth Pilot

"Stealth Pilot" wrote in message
...
On Mon, 12 Jan 2009 22:04:43 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:


"Stealth Pilot" wrote in message
. ..
On Sat, 10 Jan 2009 14:11:47 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:



--------------------------------------------------------------------------
What do you use for sand and binder? How do you mix?


you can make your own greensand.

basically you get some buckets of sand. plonk a gently running hose
into the bucket and let it float off everything but the sand.
keep the hose running until the water coming off is clear. this gets
rid of crap and non bentonite clays.

find or buy some bentonite clay.
you can buy sodium modified bentonite in 25lb bags.
you need bentonite clay because of its peculiar charactersitics. it is
different from all the other clays and the difference is what makes it
useful in casting.

ok let your washed sand dry off a bit.
weigh the sand and mix in 5% thereabouts by weight of bentonite.
this is the important bit; you need to put a coating of bentonite
around each sand particle. you dig your clean hands into the sand and
bentonite and with a handfull between your hands you run them back and
forth to work a coating of clay around each sand particle.
(your hands end up really smooth from this)

ok now you let your mix dry right out. this can take a week.

when you want to use the greensand you mix in 5% of water by weight
and nead the greensand so that it is uniformly wet out.

if you pat up a sausage out of it about 2" dia and a foot long you
should be able to hold this by an end and wave it all over the place
and none of the sand will part company.

you then need to do some test pours to see if the porosity of your
greensand means it is too coarse.

if you can handle that intelligently I'll go on to tell you why most
people get their furnaces wrong and what you need to do to get it
right.
Stealth Pilot

What's the point? If you are going to buy bentonite, why not buy a quality
molding sand like silica or olivine as well?

At any rate, good luck on your green strength test. Even the finest
seasoned
and mix green sand will in no way meet the expectation of your 2" x 12"
sample as stated.


rubbish.
I *actually* do castings.
the shake test is one I can demonstrate in 5 minutes with two
handfulls of greensand from the black bin in my workshop.
I'm writing from first hand experience.

can I suggest you get off your arse and *do* something in life.
your pleasure would increase immeasurably.

Stealth Pilot

Then whip one up in 5 minutes, and send us the pic.

"Stealth Pilot" wrote in message
...
On Mon, 12 Jan 2009 22:38:54 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:



There is also the possibility of molding this in plaster, but that's
another
story.


unless you've tried it you would have no idea how dangerous that
suggestion actually is.

firstly the strength of plaster vanishes to nothing beyond a certain
temperature. that temperature is just 5 degrees celcius above the
melting point of aloominum.

I have tried the technique to cast a mills 0.75cc diesel crankcase.
this is a tiny thing about an inch and half by an inch and a half in
overall dimensions. relatively tiny and easy to work with.
it was done lost wax.
a day after the plaster was set the mold went into the oven to melt
out the wax. it was then cooked up to about 180 degrees farenheit for
a while (2 hours afaik) to evaporate off the moisture. it stayed in
the oven overnight (I've never been allowed to use the oven again) it
was then given 15 minutes in the microwave to really dry it out.
it was wrapped in a cloth and raced out to the workshop hot.

it looked alabaster white and as dry as a piece of chalk.

when the aluminium was poured into the mold a guyser of molten
aluminium ejected to the ceiling of the workshop. this seemed to
continue for some time. an examination of the mould later showed it to
be totally empty. I dont know how dry you need to get it but I gave it
a fair go at getting a bone dry mould.

I have to ask you what your experience is in casting.
have you ever done any of this yourself or is it something you've
watched?

Stealth Pilot


Both. http://www.gp.com/build/product.aspx?pid=1569

On Jan 13, 1:00*am, Stealth Pilot
wrote:
On Mon, 12 Jan 2009 22:38:54 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:

when the aluminium was poured into the mold a guyser of molten
aluminium ejected to the ceiling of the workshop. *this seemed to
continue for some time. an examination of the mould later showed it to
be totally empty. I dont know how dry you need to get it but I gave it
a fair go at getting a bone dry mould.

Stealth Pilot

Your experience pretty much matches mine. I was able to get dry
enough plaster to make castings without porosity, but it took WAY to
long to dry to that point. My first pour too resulted in a steam
geyser and I would have sworn I baked that thing long enough. I was
also having fill problems. One plaster cast per go made the
experimentation too time consuming. I gave up and went back to sand.
I was trying to make fined valve covers for my1/2VW and was having
trouble getting molds in sand to stay together while puling the
pattern. At that time I didn't have a muller and could not get oil
based sand to work at all - thus the try at plaster. I finally
managed to modify my sand formula and got satisfactory results. A
touch of sugar did the trick.

The fins on the valve covers were enough of a challenge that I won't
be trying to do any head casting in sand, oil or bentonite based.
IMHO buying/building a muller is worth the time and trouble as the oil
based sand is good stuff. The humidity in my part of the world is
such that an uncovered covered heap of sand will dry out too much in a
matter of hours. Oil doesn't and for that reason alone I made the
switch.

Just in case you don't have the formula, even though I'm sure you
do...........................

http://www.foundry.ray-vin.com/k-bond/k-bond.htm
http://users.hal-pc.org/~lwhill/sandsystems.html

=======================
Leon McAtee