[TheForge] Strengthening castable refractory

Fri Aug 29 23:27:02 2003

Hi Chuck,

Have you ever broken a used forge, by chance, and seen if the ss needles
survive repeated heat?  Maybe if they do burn out they still help avoid
shrinkage cracks during curing.  I seem to remember that it would have been
in the ballpark of $50 and I was kind of directed away from it at the time.

Ed

----- Original Message -----
From: "Chuck Robinson" <[email protected]>
To: <[email protected]>
Sent: Friday, August 29, 2003 6:27 PM
Subject: Re: [TheForge] Strengthening castable refractory

> Hey Bruce,
> My son just dropped off a box of the needles. Under the microscope they
are
> convex on one surface and concave   on the other.
> The overall surface is also micro dimpled. I seriously doubt that they
> could be duplicated using any kind of wire or tooling available to us, and
I
> sure wouldn't find the effort, cost effective.
> $ 9 lb looks a lot more reasonable to me now.
> Chuck
> ----- Original Message -----
> From: "Bruce Freeman" <[email protected]>
> To: <[email protected]>
> Sent: Wednesday, August 27, 2003 11:19 AM
> Subject: Re: [TheForge] Strengthening castable refractory
>
>
> > What exactly ARE these  SS needles?  Short pieces of wire?  How 'bout
> > just cutting up some SS wire, instead of paying $9/lb forSS?
> >
> > Bruce
> > NJ
> >
> > >>> [email protected] 08/26/03 09:14PM >>>
> > I received some technical info from Mt. Savage on the Delta t Crete 25
> > insulating castable I'm about to use. In case anyone's interested here
> > are a couple of the specs:
> > Density after drying: 54 lbs/ cu.ft.
> > Max service temp: 2500 degF
> > Therm conductivity: 1.4 BTU/Sq.Ft./Hr/degF/in. at 500 degF
> > 1.9 at 1500 degF
> > 2.3 at 2000 degF.
> > Water for casting: Approx. 55% by weight
> >
> > Now a question. The best way to prevent checking is to use the minimal
> > amount of water. They give an approximate amount, 55%, but how do I
> > tell
> > when it's enough? From what I've read on other mixes, it should be
> > just
> > enough to hold it together when clumping it in your hand. Does that
> > sound right?
> >
> > My local refractory place has SS needles for $18 / 2 lb bag. Sounds a
> > little expensive, but not too expensive.
> >
> > Hopefully I'll get to casting this weekend. The shell is just about
> > done.
> >
> > --
> > Marc Godbout
> > http://www.ironringforge.com
> >
> > New England Blacksmiths Membership Director
> > http://www.newenglandblacksmiths.org
> >
> >
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