[TheForge] FAQ

[Mike Porter]

Jerry,
I don't think a full blown debate about tooling is possible, as we are both
pretty ruthless on the subject. "It is what it is" isn't an attitude that
allows mental moss to grow thick. The best we can hope for is momentary
differences of opinion while one of us comes up to speed. It would be
possible to work up a weak debate about naturally aspirated burners if we
weren't both pretty bored with the subject. 

To debate naturally aspirated burners would take more interest than I can
muster, for they are beginning to look too intense for my present equipment
interests (now who'd have thought a secondary flame had any virtue?), and
their flames can't be manipulated well enough to suit my hand torch wants. A
good debate is like panning for gold; I want to see enough color in the pan
to hope for some nuggets for my efforts, not rake over tailings. I'm
satisfied, and think you are too, that neither of us has much more to glean
from that stream. 

Gun burners, to use your term (where does it come from?) or fan blown (to
stay on the conservative side until I know your term is better) are of more
interest to me, equipment wise. Various oxy-fuels and compressed air torches
are my main interest hand-tool wise.  :)

On the other hand, we could hold a public brainstorming on some piece of
blacksmith equipment. A new forge design, scroll benders, the theoretical
limits of anvil design? Here's a question: given that novices don't want to
make the commitment to a good enough anvil to give proper spring-back, and
given that it isn't always convenient to use an anvil for everything we wish
to shape, and given that--at times--a soft support material is an aid during
finish work, but help (spring-back) is always useful to prevent overwork
then...

To design a limited application spring system nearly as efficient as a high
quality anvil, would you:
(A) Put the spring in the hammer handle (spring handle peening hammers?)
(B) Put a powerful (ex. coil spring from a car) spring in a support column
below the soft material
(C) Do both at different times as appropriate
(D) Do neither because "everybody knows" that only a high quality anvil is
any good to a smith. Impudent minds want to know :)

Scroll benders could be fun, but would likely turn into about a year long
discussion, what with equipment building to prove our points (too much work
without getting paid for it, or a valuable chance to refine understanding?)
Are scrolls even worth talking about anymore? I love scrolls but most people
get hives at the very thought of them after fifty years of cheap junk
scrolls flooding the market. On the other hand, when I do simple geometrical
designs people get all excited (where's the justice in such perverse
reactions? Why ask why? Ah, well. Probably no point in even discussing
picket twisting. Water-dip painting maybe?
Mikey

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Jerry Frost
Sent: Tuesday, April 18, 2006 4:14 PM
To: Sponsored by ABANA
Subject: Re: [TheForge] FAQ

Drats! How are we ever going to have a debate?

Diffusers are flame shapers, my old Johnson 133a has them. In the Johnson, 
the A:F mix is manifolded to four burner nozzles near the bottom of the 
firebox. The nozzles are flat rectangular flares that cause the flame to fan

across the bottom of the forge.

With a blower driving the flame you can make the nozzles all kinds of 
shapes. I've seen pics of needle flames, broad short cones and vortices. 
While it isn't impossible to make these things work with naturally aspirated

burners it's trickier. Guns are positive pressure and naturally aspirated 
are negative pressure devices. So, if somebody tells you naturally aspirated

burners suck you can tell them their gun burners blow. <grin>

Pick a simple conical diffuser for instance. This is just an exagerated 
version of the burner flares being used to enhance N/A burners. An 
exagerated cone diffuser will increase the draw of the burner exponentially,

making it harder to get a proper burn. On top of that an increase (flare) 
greater than 1:12 makes turbulence that makes tuning a lot harder.

Most naturally aspirated burners with diffusers are purpose built. A Fisher 
burner being a perfect example. The Fisher burner was designed to make a 
very hot close flame over a wide area. It's tube is tapered over it's entire

length from the throat to a point just below the nozzle where the body 
enlarges well more than the 1:12 ratio. Then it's capped by a perforated 
dome. The flame of a Fisher burner is (as I recall) only about 1/2" high, 
intense blue with little feathering. It spreads across the entire dome in a 
very uniform way.

There's a burner diffuser in use that's been mentioned here a few times in 
conjunction with gun burners. It's a bunch of burner nozzles in an array 
made by drilling or casting a grid of small holes in a block. A burner block

maybe? A:F is fed into the block under pressure and it makes a wide even 
"wall" of flame in the forge.

Anyway, gun burners handle different diffusers better than naturally 
aspirated burners do.

Frosty
-------------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

http://www.artmetalradio.com/

From: "Mike Porter" <michael.a.porter at comcast.net>


> Well, I'm not sure there's anything here to disagree with. When discussing
> dragon's breath, I'm referring to the end result exiting the forge. That 
> is
> not the same as the high velocity flame entering the equipment from a
> naturally aspirated burner. I like to design forges and furnaces so that
> that furious little flame is pretty well spent and puny by the time it 
> exits
> :-) Tell us more about diffusers please; greedy minds want to know.
> Mikey
> P.S. "Pandora's Tums...catchy. Now all I need is a text to go with it :)
>

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