Rocket Man VW Heads... What alloy?

[[email protected]]

Okay, then YOU name the damn things!

Right now I got a couple questions: VW heads are nearly pure
aluminum. I've got a pile of the things but odds are, every single
one of them is worth a $25 bill... or will be. Point is, I don't much
care for the idea of cutting them and melting them down.

When I make something SERIOUS out of aluminum I usually use old
pistons, which is a pretty hard alloy with a MUCH lower heat-transfer
ability than VW heads.

So what's a good alloy? Ideally, something cheap & commonly available
(and doesn't say 'Coors'!)

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

Second question: Rocket Man heads needum' rockers. I wuz thinking of
using Chebby 1.3 break-in rockers. Any better ideas? (Or rather,
any ideas at all?)

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

-Bob

[Stealth Pilot[_2_]]

On Fri, 9 Jan 2009 19:34:01 -0800 (PST), "
> wrote:

>Okay, then YOU name the damn things!
>
>Right now I got a couple questions: VW heads are nearly pure
>aluminum. I've got a pile of the things but odds are, every single
>one of them is worth a $25 bill... or will be. Point is, I don't much
>care for the idea of cutting them and melting them down.
>
>When I make something SERIOUS out of aluminum I usually use old
>pistons, which is a pretty hard alloy with a MUCH lower heat-transfer
>ability than VW heads.
>
>So what's a good alloy? Ideally, something cheap & commonly available
>(and doesn't say 'Coors'!)
>
>-------------------------------------------------------------------------------------------------------
>
>Second question: Rocket Man heads needum' rockers. I wuz thinking of
>using Chebby 1.3 break-in rockers. Any better ideas? (Or rather,
>any ideas at all?)
>
>-------------------------------------------------------------------------------------------------------
>
>-Bob

70 years ago there was an english inline 4 which has some surprisingly
state of the art aspects to the design.
it was called the gypsy major.
heads were cast out of "Y" metal. which is an aloominum alloy with
some exotic stuff in it.
those engines put out 140hp.

the use of auto engine rockers from an engine that could turn 9,000rpm
seems to have a lot going for it.
the use of auto pistons and rings has a lot going for it as well.
....and con rods.

incorporation of auto engine parts is a successfully trod path.
the jabiru engines have a number of similar included components.

Stealth Pilot

[Maxwell[_2_]]

> wrote in message
...
| Okay, then YOU name the damn things!
|
| Right now I got a couple questions: VW heads are nearly pure
| aluminum. I've got a pile of the things but odds are, every single
| one of them is worth a $25 bill... or will be. Point is, I don't much
| care for the idea of cutting them and melting them down.
|
| When I make something SERIOUS out of aluminum I usually use old
| pistons, which is a pretty hard alloy with a MUCH lower heat-transfer
| ability than VW heads.
|
| So what's a good alloy? Ideally, something cheap & commonly available
| (and doesn't say 'Coors'!)
|
| -------------------------------------------------------------------------------------------------------

The after market racing heads are usually made from 355 or 356, and heat
treated to T-6. Regardless of it's previous use, I wouldn't recommend
reclaiming anything. Every time you melt aluminum you gain and loose
elements, and usually reduce or at least changes it's physical properties.
It's too cheap and easy to just use an off the shelf alloy with known
physicals.

|
| Second question: Rocket Man heads needum' rockers. I wuz thinking of
| using Chebby 1.3 break-in rockers. Any better ideas? (Or rather,
| any ideas at all?)
|
| -------------------------------------------------------------------------------------------------------
|

Are you talking about 1.3 Chevy?

[[email protected]]

> 70 years ago there was an english inline 4 which has some surprisingly
> state of the art aspects to the design.
> it was called the gypsy major.
> heads were cast out of "Y" metal. which is an aloominum alloy with
> some exotic stuff in it.
> those engines put out 140hp.
----------------------------------------------------------------------------------------------------------------

I've played with a few of them. Mechanics called it the Australian
Gypsy (because it ran upside down). With turbosupercharging and a few
other tricks, the Major labored on well into the 1950's (as a
helicopter powerplant). But I don't recall any exotic claims about
it's aluminum head. I know you could run the early models on tractor
gas. (Damn! I can't remember the name of the little bipe that first
used the Gypsy. The wings folded back.) Anyway, the CR was about
5:1; something like that.

After WWII my dad worked on several 'Miles' aircraft that had found
their way to southern California. He got the job mostly because they
were made of plywood, but also because they used the de Havilland
engine.

One reason the engine was dry-sumped (according to my dad) was because
the thing DRANK oil. Inside the cowling it was a real swamp, unlike
the Walther, which was tidy by comparison.

As a point of interest, you should be able to air-cool virtually ANY
in-line four by sawing off the cylinders, machining what remains, then
replacing the jugs with something having fins. The tricky bit would
be casting an aluminum head. (Why does that sound familiar?) We
tried doing that with the Vega engine, which was supposed to power a
whole line of 'air-show replicas' (about 1973)

----------------------------------------------------------------------------------------------------------------------------------------------
>
> the use of auto engine rockers from an engine that could turn 9,000rpm
> seems to have a lot going for it.
> the use of auto pistons and rings has a lot going for it as well.
> ...and con rods.
---------------------------------------------------------------------------------------------------------------------------------------------

Prolly not as much as you think. It's the PROPELLER that dictates the
'life-style' of an aircraft engine. The fact you've used rockers from
an engine that turns six grand doesn't mean a lot. Stock VW valve-
train components are good to above 5-grand... if you don't go crazy
with the valve-spring tension. But anything faster, you're going to
need push-rods like telephone poles... and valve springs that would be
right at home in a landing gear.
--------------------------------------------------------------------------------------------------------------------------------------------

> incorporation of auto engine parts is a successfully trod path.
> the jabiru engines have a number of similar included components.

-------------------------------------------------------------------------------------------------------------------------------------------
Sure. Any time you can utilize an off-the-shelf, mass-produced
component you'll be money ahead. The expensive bits are billet cranks
and custom cams.

Nowadays we've got filled-epoxy compounds that do as well as castings
for such things as sumps, rocker covers and so on.

-Bob

> Stealth Pilot

[[email protected]]

On Jan 10, 9:18*am, "Maxwell" <#$$9#@%%%.^^^> wrote:
|
> | So what's a good alloy? *Ideally, something cheap & commonly available
> | (and doesn't say 'Coors'!)
> |
> | -------------------------------------------------------------------------------------------------------
>
> The after market racing heads are usually made from 355 or 356, and heat
> treated to T-6.
---------------------------------------------------------------------------------

Are you talking air-cooled heads?

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

> Regardless of it's previous use, I wouldn't recommend
> reclaiming anything. Every time you melt aluminum you gain and loose
> elements, and usually reduce or at least changes it's physical properties..
> It's too cheap and easy to just use an off the shelf alloy with known
> physicals.
> ------------------------------------------------------------------------------

I'm afraid you've confused me with some of those Double-Dipper Retired
Military types :-) Whatever I use for casting will have to come from
the junk yard.

I can get two engines-worth of 1.3:1 rockers for $200, which is about
the only thing I'd care to buy. I'll hit the junk yards over by the
airport to see if I can come up with the studs & hardware.

My casting ability is limited to about one quart of melted aluminum,
which should be enough for the type of heads I'm thinking about.

This puppy is going to need two cores. Pulling an accurate core is
where I've had trouble in the past. That is, using the Old Fashioned
method of baking cores. (Smells like a batch of cookies... until the
cores reach the carbonizing stage. In the past, I've scheduled Core
Production for those times when I'm home alone... then try to air-out
the kitchen before my wife returns :-)

It's unfortunate that, with almost a thousand 'subscribers,' grass-
roots ideas such as this, the primary glider and so forth, garner so
little attention. On the other hand, I continue to suffer what the
physicians refer to as 'mini-strokes' that leave me wanting when I try
to recall something like a pass-word or telephone number... with the
'chuggers' Group being a good case-in-point. I've no idea in the blue-
eyed world what 'chuggers' expects for my screen-name or password.
(Kinda reminds me of the two geezers who went for a local hop in the
one's freshly licensed home-built, which began with a neat diving turn
to pass UNDER a local powerline. But he finally climbed up to a sane
altitude and except for sneaking in a bit of input now & then, the
flight was a lot of fun. Unfortunately, as they began lining up for a
landing the pilot made no reduction in power until his friend shouted,
"Keee Rist! Jim! Are you trying to get us killed?" To which Jim gave
his friend a guilty look. "Actually, I thought YOU were flying
today.")

Still flying today.
-Bob

[Maxwell[_2_]]

> wrote in message
...
On Jan 10, 9:18 am, "Maxwell" <#$$9#@%%%.^^^> wrote:
|
> | So what's a good alloy? Ideally, something cheap & commonly available
> | (and doesn't say 'Coors'!)
> |
> | -------------------------------------------------------------------------------------------------------
>
> The after market racing heads are usually made from 355 or 356, and heat
> treated to T-6.
---------------------------------------------------------------------------------

Are you talking air-cooled heads?

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

Which sand cast alloys do you thing will conduct heat significantly faster?







> Regardless of it's previous use, I wouldn't recommend
> reclaiming anything. Every time you melt aluminum you gain and loose
> elements, and usually reduce or at least changes it's physical properties.
> It's too cheap and easy to just use an off the shelf alloy with known
> physicals.
> ------------------------------------------------------------------------------

I'm afraid you've confused me with some of those Double-Dipper Retired
Military types :-) Whatever I use for casting will have to come from
the junk yard.
--------------------------------------------------------------------------------

Why, you can buy certifed spec metal for $1.50 to $2.00 a pound.







I can get two engines-worth of 1.3:1 rockers for $200, which is about
the only thing I'd care to buy. I'll hit the junk yards over by the
airport to see if I can come up with the studs & hardware.
--------------------------------------------------------------------------------
Are you talking about Chevy rockers?




My casting ability is limited to about one quart of melted aluminum,
which should be enough for the type of heads I'm thinking about.

This puppy is going to need two cores. Pulling an accurate core is
where I've had trouble in the past. That is, using the Old Fashioned
method of baking cores. (Smells like a batch of cookies... until the
cores reach the carbonizing stage. In the past, I've scheduled Core
Production for those times when I'm home alone... then try to air-out
the kitchen before my wife returns :-)
--------------------------------------------------------------------------
What do you use for sand and binder? How do you mix?

[bod43]

On 10 Jan, 18:32, " > wrote:
> > 70 years ago there was an english inline 4 which has some

> other tricks, the Major labored on well into the 1950's (as a
> helicopter powerplant). *But I don't recall any exotic claims about
> it's aluminum head. *I know you could run the early models on tractor
> gas. *(Damn! *I can't remember the name of the little bipe that first
> used the Gypsy. *The wings folded back.) *Anyway, the CR was about

Tiger moth used the Gypsy Major - no idea if it was the first.

I did about 15 hours (dual except for one solo) in
a Chipmunk in the early '70s behind a Gypsy Major
and only had one failure:)

One mag drive gear stripped leaving the mag going
round a bit, lots of popping and banging.
Oh, at 500ft on the way up.

Kept going enough to maintain level flight but it
was disapointing that we were not high enough to
jump out.

Try that without dual ignition! Would have
been in a load of **** in this case since the
shipyards and the river (fixed gear taildragger,
not recommended for ditching) were not inviting.
Don't suppose they would have been more inviting
under a parachute:)

[[email protected]]

On Jan 9, 8:34*pm, " > wrote:
> Okay, then YOU name the damn things!
>
> Right now I got a couple questions: *VW heads are nearly pure
> aluminum. *I've got a pile of the things but odds are, every single
> one of them is worth a $25 bill... or will be. *Point is, I don't much
> care for the idea of cutting them and melting them down.

VW head cores are worth that much!? I've melted away a fortune :-(

>> When I make something SERIOUS out of aluminum I usually use old
> pistons, which is a pretty hard alloy with a MUCH lower heat-transfer
> ability than VW heads.

>
> So what's a good alloy? Ideally, something cheap & commonly available
> (and doesn't say 'Coors'!)
>

IMHO anything that would fill the mold and not shrink too much would
be usable.
Late model automatic transmission cases work for me. Pours like water
and machines clean.


If I were doing it for sale or use by another I'd probably spend the
money on fresh ingots.

> -------------------------------------------------------------------------------------------------------
>
> Second question: *Rocket Man heads needum' rockers. *I wuz thinking of
> using Chebby *1.3 break-in rockers. *Any better ideas? *(Or rather,
> any ideas at all?)
>
Chevy would be my choice as well, but given that they may not make the
year maybe we should be looking at Ford parts :-)
There will be a demand for after market small block Chevy parts until
we run out of oil so that is where we vultures should be looking.

However I've been trying to remember since this thread popped up where
I ran across some nice rockers that had built in hydraulic lifters not
much bigger than the adjusting screws in a TP IV..
=======================
Leon McAtee

[Stealth Pilot[_2_]]

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

[Stealth Pilot[_2_]]

On Fri, 9 Jan 2009 19:34:01 -0800 (PST), "
> wrote:

>Okay, then YOU name the damn things!
>
>Right now I got a couple questions: VW heads are nearly pure
>aluminum. I've got a pile of the things but odds are, every single
>one of them is worth a $25 bill... or will be. Point is, I don't much
>care for the idea of cutting them and melting them down.
>
>When I make something SERIOUS out of aluminum I usually use old
>pistons, which is a pretty hard alloy with a MUCH lower heat-transfer
>ability than VW heads.
>
>So what's a good alloy? Ideally, something cheap & commonly available
>(and doesn't say 'Coors'!)
>

>-Bob

according to some evening research there are two aloominum alloys used
in automotive(water cooled) heads. AA319 which has Aluminium plus 6%
Si and 3. 5% Cu and AA 380 Aluminium plus8.5% Si and3% Cu

another source shows an old piston alloy 242 as a popular aircooled
head alloy.

lyc and cont use a 2 series alloy.

one reference mentions 220.0 -T61 as the original widely used
aircooled head alloy though now supplanted by 242.0 and 243.0 which
supposedly have better elevated temperature heat strength.

242 alloy is Aluminium with Mg 3.0%, Si 0.5%, Fe 0.5%, Mn 0.2%, Zn
0.1%, Cu 0.05% (percentages by weight)

so as a wild guess your silicon containing piston alloy mixed with
some 2024 or 6061 might just be entirely satisfactory. experimentation
will tell.

Stealth Pilot

[GeorgeB]

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

[[email protected]]

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

[Maxwell[_2_]]

"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.

[Maxwell[_2_]]

> 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.

[[email protected]]

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

[Stealth Pilot[_2_]]

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

[Stealth Pilot[_2_]]

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

[Maxwell[_2_]]

"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.

[Maxwell[_2_]]

"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

[[email protected]]

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

[Fred the Red Shirt]

On Jan 13, 3:00*am, Stealth Pilot >
wrote:
> 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.

That is because it is water molecules that bind the other molecules
together when the plaster cures. When you heat it, you break those
bonds and drive off the water.

You can test this out by weighing the water and plaster you mix,
then weigh the cured solid when it appears dry. It will still weight
a lot more than the dry plaster did. After baking it, weigh it
again.

As long as the weight is greater than the original dry plaster, you
know there is still water in there.

>
> 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've no experience, but there is a nice newsgroup called
rec.crafts.metalworking or something like that where you
can get good advice from people who routinely have a
less exciting experience.

Plaster of Paris retains water of crystalization when it is
cured. It takes a lot of heat for a long time to get all of that
water out, like maybe 5 or 6 hours at 500 F and you should
keep it hot when you our. If I understand the chemistry, by
the time it is dry enough to cast aluminum you will have returned
it to much the same material that it was before you mixed
it. Since you didn't do that, it was the molten aluminum
that decomposed the plaster releasing the water with the
observed result.

Jewelers work with much higher melting point metals, platinum
even. They use investment, sometimes called investment plaster.
The difference between that and ordinary Plaster of Paris is that
it has materials added like silica that do not decompose when the
mold is burnt out, and other materials (maybe wood flour) that are
there to create microporosity when it is burnt out. A high quality
investment may be overkill for casting aluminum, but it will be
better than a molten aluminum geyser.

But please do check with people who, unlike myself, have
actually done this.

On to the subject of cooling fins:

I HAVE designed cooling fins back in a former life when I
was working in the nuclear industry. I believe you will
get the best heat transfer with pure aluminum. Alloys
will have a lower thermal conductivity, although the
more important parameter is heat capacity, the product
of thermal conductivity with density. But for an airplane
you probably don't want denser (and therefore heavier
materials).

You can improve the heat transfer and reducing the
weight by tapering the cooling fins from root to tip. A
good undergraduate engineering book on heat transfer
should address the optimization of cooling fins.

Remember also that convective heat transfer is
governed by Newton's law of cooling:

q = mdot * h * A * deltaT

DeltaT is the temperature difference, A is the surface
area (which you increase with fins), h is the convective
heat transfer coefficient (usually a function of Reynold's
number) and mdot is the mass transfer rate of the cooling
fluid.

Bumping up the flow increases both mdot (directly) and
h, by increasing the Reynold's number. It helps a lot.

IOW, concentrating on improving the airflow may be more
helpful than improving the fins.

Hope this helps

--

FF

[Fred the Red Shirt]

On Jan 12, 11:04*pm, "Maxwell" <#$$9#@%%%.^^^> wrote:
>
> ...
>
> What's the point? If you are going to buy bentonite, why not buy a quality
> molding sand like silica or olivine as well?

Kitty litter is cheap.

--

FF

[[email protected]]

> IOW, concentrating on improving the airflow may be more
> helpful than improving the fins.
>---------------------------------------------------------------------------------------

Roger that. In spades. Most homebuilt cooling systems aren't. Go
over to AirVW and give a gander at what one of the Monnett's had to
say about VW heads.... and later what he had to say about VW cooling
systems.

x-number of inches of water-pressure differential between the inlet
plenum and the outlet plenum... takes something on the order of 90mph
to get that amount of pressure from ram air alone. And you're driving
a plane that cruises @ 75mph

So now you REALLY get to see the Wizards at work... guys like John
Thrope, with his equations for the inlet AREA of the plenum vs the
outlet area, with pieces of duck tape here & there and flat THROWING
the stock oil cooler across the hangar because it's making such a huge
HOLE in the back wall of his inlet plenum that there ain't no way to
get the required about of pressure... and the Great Designer insisting
he's NEVER had any 'trouble'... and it reminds you of the guy in
Oregon with his three engines but never any trouble, or the guy in
Canada with 1300 hrs on the SAME engine over a 20 year period and
NEVER ANY TROUBLE... but forgetting to mention the ANNUAL 'freshening
of the valves' and the occasional replacing of the bearings because
THOSE THINGS DON'T COUNT as 'troublle' since he's never had any in all
those long, long twenty whole YEARS of flying.... which worked out to
something like 65 HOURS OF FLYING PER YEAR, between June and
September, because that is the flying "..season..." according to this
particular expert with his high-time VP1 now a'dangling in some
museum.

The only thing more lovable than a VW-powered air plane is the folks
that owns them.

-R.S.Hoover

[Stealth Pilot[_2_]]

On Tue, 13 Jan 2009 08:42:55 -0800 (PST), "
> wrote:

>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

priceless references.
I've never tried oilsand just a seemingly continuous tweaking of my
bentonite based mix getting it better and better.

maxwells investment reference gives little actual detail but they must
do some cunning stuff with the additives that they allude to in their
plaster. they've certainly developed the process way beyond what I've
achieved.
Stealth Pilot

[Stealth Pilot[_2_]]

On Wed, 14 Jan 2009 12:52:18 -0800 (PST), "
> wrote:

>
>> IOW, concentrating on improving the airflow may be more
>> helpful than improving the fins.
>>---------------------------------------------------------------------------------------
>
>Roger that. In spades. Most homebuilt cooling systems aren't. Go
>over to AirVW and give a gander at what one of the Monnett's had to
>say about VW heads.... and later what he had to say about VW cooling
>systems.
>

I changed some baffles on the O-200 to get around a corrosion problem.
airborne moisture was impacting the fins, blasting off the paint and
then leaving the bare hot steel moisture coated. rust city.

later I noticed some harsh running sounds and while investigating some
oil leaks had the need to replace rocker gaskets.
on one cylinder there was a noticeable build up of carbonised charred
oil on the top of the exhaust valve.
I've since placed a hole in the baffle face to direct air over the
exhaust fins of that cylinder, rather than using the plenum pressure
directed airflow.
The harsh noises have not reoccurred. during the annual in a few
months I'll check for carbon buildup again.

do you find in your vw engines that carbon buildup on the exhaust
valves is any indication of a cooling deficiency?
what indicator do you use for health of a cooling setup?
in other words how can anyone know that they have it right?

in my case oil temps were all totally normal. it seemed to me that the
charred oil was an indicator of a local hot spot that I needed to
address.

Stealth Pilot

[Stealth Pilot[_2_]]

On Tue, 13 Jan 2009 07:16:12 -0600, "Maxwell" <#$$9#@%%%.^^^> wrote:

>

>>>
>>>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.
>

after the last time? c'mon even george bush thinks that twice is
stupid.

[[email protected]]

On Jan 14, 5:23*pm, Stealth Pilot >
wrote:

> do you find in your vw engines that carbon buildup on the exhaust
> valves is any indication of a cooling deficiency?
> what indicator do you use for health of a cooling setup?
> in other words how can anyone know that they have it right?
----------------------------------------------------------------------------------------------

Detonation gets your attention pretty fast.

SPLIT in the exhaust valve.

Guy sez temps are good and you're standing there with you IR
temperature gauge, with it say 530F and he's still yaking on about his
'good temperature,' with the thermocouple under his sparking plug.
Ask AGAIN and he starts talkng about fishing or some dum-assed thing.

-Bob

[[email protected]]

On Jan 14, 12:46*pm, Fred the Red Shirt >
wrote:

> Kitty litter is cheap.


PLEASE don't mention anything about "kitty" around a casting sand
heap ........ Bad Karma :-)
=================
Leon McAtee

[Maxwell[_2_]]

"Stealth Pilot" > wrote in message
...
> On Tue, 13 Jan 2009 07:16:12 -0600, "Maxwell" <#$$9#@%%%.^^^> wrote:
>
>>
>
>>>>
>>>>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.
>>
>
> after the last time? c'mon even george bush thinks that twice is
> stupid.

Once again, I didn't think so.

[Maxwell[_2_]]

"Fred the Red Shirt" > wrote in message
...
On Jan 12, 11:04 pm, "Maxwell" <#$$9#@%%%.^^^> wrote:
>
> ...
>
> What's the point? If you are going to buy bentonite, why not buy a quality
> molding sand like silica or olivine as well?

Kitty litter is cheap.

=========================

Yeah, but the castings it produces is pure ****. :)

[Maxwell[_2_]]

"Stealth Pilot" > wrote in message
...
> On Tue, 13 Jan 2009 08:42:55 -0800 (PST), "
>
> maxwells investment reference gives little actual detail but they must
> do some cunning stuff with the additives that they allude to in their
> plaster. they've certainly developed the process way beyond what I've
> achieved.
> Stealth Pilot

It wasn't an investment reference, just a casting plaster.

[Fred the Red Shirt]

On Jan 15, 12:30*am, "Maxwell" <#$$9#@%%%.^^^> wrote:
> "Fred the Red Shirt" > wrote in ...
> On Jan 12, 11:04 pm, "Maxwell" <#$$9#@%%%.^^^> wrote:
>
>
>
> > ...
>
> > What's the point? If you are going to buy bentonite, why not buy a quality
> > molding sand like silica or olivine as well?
>
> Kitty litter is cheap.
>
> =========================
>
> Yeah, but the castings it produces is pure ****. *:)

I think you need to cover your sand better between uses...

--

FF

[Maxwell[_2_]]

"Fred the Red Shirt" > wrote in message
...
On Jan 15, 12:30 am, "Maxwell" <#$$9#@%%%.^^^> wrote:
> "Fred the Red Shirt" > wrote in
> ...
> On Jan 12, 11:04 pm, "Maxwell" <#$$9#@%%%.^^^> wrote:
>
>
>
> > ...
>
> > What's the point? If you are going to buy bentonite, why not buy a
> > quality
> > molding sand like silica or olivine as well?
>
> Kitty litter is cheap.
>
> =========================
>
> Yeah, but the castings it produces is pure ****. :)

I think you need to cover your sand better between uses...

=============================================

Why would anyone want to use things like top soil and kitty litter for
molding metal castings, when high quality molding sands and binders sell for
as little as 10 to 15 cents a pound, and are often reusable?

Same thing with alloys. Scrap aluminum usually sells for about 1/4 the price
of high quality ingot, a difference of about 75 cents a pound. In a 10 pound
cylinder head you are investing an additional $7.50 per head to buy the
best.

[Fred the Red Shirt]

On Jan 15, 7:07*pm, "Maxwell" <#$$9#@%%%.^^^> wrote:
> "Fred the Red Shirt" > wrote in ...
> On Jan 15, 12:30 am, "Maxwell" <#$$9#@%%%.^^^> wrote:
>
>
>
> > "Fred the Red Shirt" > wrote in
> > ...
> > On Jan 12, 11:04 pm, "Maxwell" <#$$9#@%%%.^^^> wrote:
>
> > > ...
>
> > > What's the point? If you are going to buy bentonite, why not buy a
> > > quality
> > > molding sand like silica or olivine as well?
>
> > Kitty litter is cheap.
>
> > =========================
>
> > Yeah, but the castings it produces is pure ****. :)
>
> I think you need to cover your sand better between uses...
>
> =============================================
>
> Why would anyone want to use things like top soil and kitty litter for
> molding metal castings, when high quality molding sands and binders sell for
> as little as 10 to 15 cents a pound, and are often reusable?

I expect the cats will **** in it regardless.

I can buy high quality bentonite clay at the grocery store and
sand at the local home center. It's really not the price, it's
the convenience. If I get seriously into casting I may look
for a local source of good green sand. If I have to buy it mail
order
I might stick with the home made stuff.

For now I'm just fooling around with pewter, but want to move
up to bronze. I may just stick to investment plaster, (which
I bought) as what I have planned are some pretty small parts.

>
> Same thing with alloys. Scrap aluminum usually sells for about 1/4 the price
> of high quality ingot, a difference of about 75 cents a pound. In a 10 pound
> cylinder head you are investing an additional $7.50 per head to buy the
> best.

I understand your point. Scrap is fine for practice, and is often
available
for free.

[gorgon]

On Jan 14, 9:59*pm, "
> wrote:
> On Jan 14, 12:46*pm, Fred the Red Shirt >
> wrote:
>
> > Kitty litter is cheap.
>
> PLEASE don't mention anything about "kitty" around a casting sand
> heap ........ Bad Karma :-)
> =================
> Leon McAtee

Leon,

You and I may know that bentonite is a local phenom that is generally
a pain in the a**. Others think it is a ephemeral magic substance.
We live in one of two places on earth (the other is in central Russia)
that have an excess of the stuff. While we can get a ton or so from
down the road, others have to resort to kitty litter or draining the
local Hooter's mud wrestling pits (in Wyoming, Hooters are goose calls
or pickup horns).

For those of you who don't drive on greenish, slick as snot, expansive
clay as a rule, or build your houses on land that rises and falls
annually by a couple of feet due to humidity, bentonite sucks.

Should you want some....let Leon or me know and we can UPS or
otherwise ship 50 pound bags of the stuff. We have it in our back
yards.

Mark