[TheForge] photos under "inexpensive recuperative forge"

[Michael]

Frosty,

My only real concern with this forge design is a matter of style;
fortunately, you and I don't think exactly alike. What is good about that,
beyond being able to hold a lively conversation, is that we are bound to
come up with a greater variety of equipment. It has been a little difficult
for me to "put the finger" on just what it is about this design that doesn't
click, but overall, I'd say the problem lies in the fact that it is a forge
design; I have been thinking in the brazing hearth mode for two years now.
So, recuperation and every other technical detail is slanted that way for
me. In other words, ceramic chip "forges" and nothing else. This design
would work very well without the chips, freeing it to take whatever shape
you like, but leaving me thinking it just wouldn't dove tail perfectly with
my own desires. However, I never expected to sneak up on everyone with
brazing hearths (never stop trying though :)

Mikey

 

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Jerry Frost
Sent: Sunday, July 23, 2006 5:25 PM
To: Sponsored by ABANA
Subject: Re: [TheForge] photos under "inexpensive recuperative forge"

 

No sweat Mike.

 

I recall your concern for the burner nozzle from the 

last discussion and thought I'd addressed it but may 

not have. I get distracted so easily any more. <grin>

 

Today for instance, I've been plugging away on my shop 

for about three summers now and today when I went out I 

spent probably an hour and couldn't come up with a 

single thing to do except start hanging the skin on it. 

Talk about a distraction! <grin>

 

Anyway, a burner in an induction circulation 

recuperative wall furnace (man is that a clumsy mouth 

full!) is no more vulnerable to excess heat than a 

single wall furnace. The nozzle, flare, etc. doesn't 

extend into the gap so it has the outer wall for 

protection. In fact, temps in the gap will be well less 

than in the furnace chamber so nozzle life should be 

significantly better.

 

If the burner port in the outer furnace wall is made 

with a 1:12 taper, if you use a flare at all, then the 

burner tube can be mounted to the exterior shell with a 

pipe flange and there is so little heat effect as to be 

nonexistant.

 

Here's another plus to add to the list of reasons to go 

to all the hassle of making a double wall forge. In 

addition to greater heat and fuel economy, 

recirculating the exhaust gasses will eliminate any 

excess oxy in the forge chamber. This means we can run 

the burner closer to a neutral air/fuel ratio and 

maintain a carburizing environment.

 

So, here's my list of plusses. Recirculating exhaust 

(semi-burnt air/fuel) through a gap in a double wall 

furnace rather than exhausting it directly out of the 

furnace:

 

#1 Keeps fire in the chamber longer for greater BTU 

exchange. (Economy)

 

#2 Fire heats both sides of the inner wall so the 

absolute temp in the furnace chamber is higher. 

(Efficiency)

 

#3 Fire temperature in the gap is lower than normal 

forge temp so there is less heat loss through outer 

liner and shell. (Economy)

 

#4 Excess oxy and fuel is consumed completely allowing 

leaner mixture to the burner without creating an 

oxidizing environment in the forge chamber. (Economy)

 

    4a. More neutral air fuel mix to the burner means 

less CO and other noxious exhaust products. (Health & 

Safety)

 

    4b. Reduced dragon's breath. (Comfort & Safety)

 

#5 Greatly extended burner life. (Economy)

 

#6 Last (That's occured to me anyway) but not least; 

much quieter operation. The gap is a natural and 

integral muffler. (Comfort, Health & Safety)

 

The real downside of building a forge like this is the 

extra hassle but seeing as I build double lined forges 

anyway, what's the big deal about putting some space 

between them. <grin>

 

Frosty

-------------------------------

If it ain't forged

it ain't real.

Wrought iron is.

The FrostWorks

 

Meadow Lakes, AK.

 

http://www.artmetalradio.com/

 

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

 

 

> Frosty,

> OK, we will call induction method one, and the other 

> three can move down the

> desirability scale. I had forgotten induction, 

> although you had gone into it

> thoroughly last summer. It is hard to believe this 

> conversation is a year

> old! I didn't like induction at the time, because of 

> the probable increased

> heat gain in the burner, but that is because I'd 

> forgotten about cast

> refractory burner nozzle/mixing chambers. It wouldn't 

> be so bad; becoming

> vague, if the fuzziness also applied to "my most 

> embarrassing moments."

> Alas, they still come back in full Technicolor (and 

> then some >:-)))

> Mikey

> 

 

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