[TheForge] Kaowool vs Soft Fire Brick

[Bruce .]

Danr,

You're way outside my experience, but let me add my 2c:

A swordsmith I know seems to prefer a propane forge made of a freon
cylinder -- stood upright, ~9" OD.  Front and back openings 2"wide x 3"
high.  He lines it with kaowool, 2" thick, I believe.

Borax is a bitch on kaowool.  A thin sheet of SS might stop that problem.
Maybe a different flux would be less of a problem -- sharp sand, or
Nedbor's "Black Magic" might remain solid in the absence of iron oxide
scale, but I don't know that for sure.

Unfortunately, borax is also a bitch on soft firebrick.  Again, SS, or a
kiln shelf might solve that problem.

I think the root of the problem is the length of the forge.  It takes a lot
of heat to get it up to welding temperature.  Have you considered
increasing (like, doubling) the layer of kaowool?

The only other thing I can think of is to somehow increase the rate at
which you feed propane to the burners.  Presumably, you're using some sort
of orifice, which could be changed out for a larger one.

Hope this helps.

Best of luck.

Bruce
NJ

On Thu, Aug 18, 2016 at 11:59 AM, Daniel Kretchmar <dan at irontreeworks.com>
wrote:

> I apologize for the misunderstanding. I was not clear about the problem.
>
>  I have built several gas forges over the years, both self aspirating and
> forced air.  The one I want to rebuild is inside a 40 lb propane tank with
> a 2 inch shell of Mizzou,  a 1 inch layer of Kaowool coated with Satanite.
> The bottom of the forge is 1 inch hardbrick.  The forge is about 18 inches
> long.  It has two burners, each with it's own squirrel cage blower, gate
> valve to control the air, and a pin valve to control the gas.  Each burner
> uses is own propane tank.
>
> The problem I am having is two fold. The hot borax has forced me to rebuild
> the Kaowool layer several times.  The borax flows down along the hardbrick
> floor and melts the kaowool along the edges.  I was wondering if Soft brick
> would prevent this. The second problem is heat. The forge ISN'T getting hot
> enough to weld larger pieces. I can weld smaller billets (12 inches long x
> 1 inch wide x 2 inches thick) but I am having trouble welding longer and
> wider pieces.  I want to make a replica of the Sutton Hoo sword, which is
> made from as many as 6 (or 12) billets, (4 billets of 7 layers each with
> twists every 4 cm and 160 layers for the outer 2 edges)  The 6 billets are
> approximately: 85 cm x 1.5 cm x 1.5 cm each.  I need to weld all six of
> them together into a single billet.  I need to weld about 6 inches at a
> time, with an overlap weld of about 2 inches each weld.  This means that I
> weld 6 inches, move down the billet 4 inches and weld the next 6 inches
> until I have welded all 85 cm.  My forge is not getting the billet hot
> enough to weld such a big billet.  I have welded it together in charcoal,
> but I want to weld it in propane
>
> Here is pic I found online:
>
> https://s-media-cache-ak0.pinimg.com/564x/f9/e2/34/
> f9e234b6f6e077265f6eee045ce55e8d.jpg
> )
>
> Suggestions are appreciated
>
> Danr
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