pdp1@EARTHLINK.NET on sun 28 nov 04
Hi Lela, Gordon,
Yes...it did sound as if there had been some confusion
there...
My recollections...
The Wax entity which in effect IS the actual 'Original'
Artist's sculptural thing, is then encased into a Plaster
Mould (with sprues and breather-vents attatched to it and so
on) for the so called 'Lost Wax' method, the Wax entity of
course is cooked off in an oven to leave only it's cavity in
the Mould.
The Mould then becomes as close as anyoine is going to get
to the 'Original', or, is, in effect, an 'Original Mould'.
Wax or other materials may of course be used to make an
entity for producing a cavity in some medium or other, for
being a Mould for Castings to be made, where the original
entity is not lost, but, is retained as a souvineer or for
use again later in new Moulds, even if the Mould is
semi-perminent, such as refractory plaster Moulds may be.
I have cast Red Brass in moulds I made from some Refractory
Plasters, keyed to close neatly, having used a Mahogany
'original' entity I had fashioned, and it worked very well.
There is no reason I can think of why this manner of Mould
would not be well suited for Bronze whose melting point is
in fact, just a little less I think than Red Brass, or, is
close to it anyway. While Bronze is known to fill out a
cavity in a Mould more nicely than Red Brass usually does,
or, more readily...hence is elected for 'Art' things for
it's more fluid properties in the pour and also for it's
shrinking very little if at all as it cools.
Sand Casting of course is a more usualy resort, and for
which, the impression or cavity one has is used only one
time usually...but with care, can be used several times if
the Sand and all allows it.
Phil
el v
Snail Scott on mon 29 nov 04
At 02:25 PM 11/28/2004 -0800, Phil wrote:
>I have cast Red Brass in moulds I made from some Refractory
>Plasters, keyed to close neatly, having used a Mahogany
>'original' entity I had fashioned, and it worked very well.
>There is no reason I can think of why this manner of Mould
>would not be well suited for Bronze...
A 'cope and drag' or multi-part reusable
mold can certainly be used for bronze. The
prevalence of 'waste' molds (luto or shell)
is generally because more complex forms can
be cast without concern for 'draft'. Any
degree of undercut or hollowness may be
achieved with a waste mold. For forms which
can be achieved with a reusable piece mold,
though, it can be an efficient means of
production.
-Snail
pdp1@EARTHLINK.NET on tue 30 nov 04
Hi Snail,
Yup...and yup-again...
I was (of course?) thinking of smallish, simpler or less
extendedly
three dimensional forms for whom seperable Moulds recommend
themselves.
But for a complex form, eeeeesh, it would be quite an
endevor I expect to be about making a five or six piece
Mould, were one so disposed...could be fun though I guess...
One time, I got all inspired to make a pair of 'Alloy'
Cylinder Heads for my 'bike, which came with Iron heads in
it's day. So I made some Wood patterns as had the combustion
chamber size and shape ("Navarro") I wanted, and anticipated
how one could mill 'em down too if one wanted to bring the
compression some ways 'up' without the Piston-top hitting
anything in case one was running them on a stoker ( I
wasn't, but I mighta made some several sets, and who knows
about the next guy's Engine, ) and as had a nice
cooling-fin pattern and so on too, and which anticipated the
amount of shrink the Alloy I was going to use was known to
do in it's
cooling unto solid...and I never did get any Cast up. These,
of course, would have been the Patterns for a Sand Mould.
But like a lot of
things, making the patterns was a good excercise and I
enjoyed it. Lots of little draft considerations on them fins
and so on...
Anyway, I would someday like to get into produceing
Aftermarket period-correct accessory Heads and other stuff
for some of the old 'bikes and Cars, but hell, I waited so
long now to do so, there is a lot of guys into those things
now, but at least there is still room for things as are done
well, which most of that stuff being done now, isn't.
Anyway...
Fun stuff...
Phil
el v
----- Original Message -----
From: "Snail Scott"
> A 'cope and drag' or multi-part reusable
> mold can certainly be used for bronze. The
> prevalence of 'waste' molds (luto or shell)
> is generally because more complex forms can
> be cast without concern for 'draft'. Any
> degree of undercut or hollowness may be
> achieved with a waste mold. For forms which
> can be achieved with a reusable piece mold,
> though, it can be an efficient means of
> production.
>
> -Snail
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