Re: Lost Foam casting inquiry


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Posted by bpfink on November 01, 1999 at 20:57:05:

In Reply to: Re: Lost Foam casting inquiry posted by Sander Rosenberg on October 28, 1999 at 21:20:20:

And I thank you also for a most informative laying of the hands on the posts.

If you know me, you also know I am in love with this media and jargon of missives.

And this is not specifically directed to you Sander but to the very question it poses.

Also that I am also just another Bozo on the Bus that does want to help but that also is self educated via many years of this and will make many more mistakes (God willing) and so treat me with a grain of Paprika.

DEFINITION self taught: Crazily gleaning from anywhere and everywhere but not paying an institution to spoon feed while actually interested in other dominate pursuits.

The 'choking' of the sprue section just a short distance before it enters the main body of the casting is really a good idea when working large since it helps the metal 'crystals' form in a pattern that is 90 degrees to the surface when it cools. They do that, don't ask me why. This means that if there is any pulling shrinkage of the metal it will tend to NOT pull a section off the main body casting but will instead 'tear' or break in a segment of the sprue and leave the main body alone.

And then it did not work as well overall...

Ah so is the matrix of space in life.

So many castings, so little time....

Actually as with any rule there is always another exception; which makes this physical world such a fun place to muddle about and learn from the causes and effects (if only we allow it to be instructive).

When casting with a burnout styrofoam body the need to get that out of the way is more important so the metal can get to where it is going.

So no need to choke the sprue.

Not that it is not a great idea, but that it often just does not work.

(We have all had great ideas that did'nt work so I know you must know what I refer to.)


"So no need to choke the sprue with styrofoam casts when using as as you pour burnout systems."... still a good idea for the metal cooling / crystal formation / weak link and voted "best place to break" part but one has to make sure that the metal even fills the whole form first or it is of no use.

Until that is conquered.

NOTE**** many other ways to do that,

it is not that we do not have all the answers, just that we often don't realize what the questions are. (my lovely Charlene informs me often.)

In order to help get that hot stuff down the shaft you can either make a pre heated (via) hot rod poker opening, or a hollow shaft in the styrofoam sprue, or.... on and on.

Also large non connected shafts of styrofoam set adjacent to the body and to be filled at the same time... or nickel nichrome looped wire inserts that are given their voltage due prior to the


get the drift.

AND of course all of these will not always work with rules, but Moxie and a Guardian angel angle do wonders with a pinch of salt....

At least sometimes.







This is actually a plea to keep an open mind and enjoy the pursuit. Let your students know that while good research helps map a path and set a course, you don't have to know where you are going to enjoy the road your on.

Good pursuit, and do keep in touch

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