[TheForge] Chip Bed Forge

Thu Feb 16 12:02:17 EST 2006

Michael,
 Try Flame Engineering if you want to find "state of the British art" crafts 
heating equipment. Unfortunately, every bit of their stuff is also quite out 
of date. England and the rest of Europe designed all their forging/brazing 
equipment to run off of butane--not propane. Butane had been thought to have 
several advantages over propane. One of them is that butane receives a big 
flame temperature boost (356 degrees more than propane) from a lot less 
added oxygen (a ratio of 1.8 to 1 instead of propane's 4.7 to 1). But, the 
main advantage was supposed to be safety. Propane cylinder pressure is 109 
PSI at room temperature, to butane's 17 PSI. Sounds almost to good to be 
true, right? Well, it is. Lower pressure turned out to be a mixed blessing 
at best. You see, all their heating equipment needs large expensive 
motor/compressors, and the attendant safety equipment that goes with such a 
system...and we find it all down hill from a design standpoint from there. 
Oh sure, 17 PSI is plenty of pressure to establish a flame with, but the 
fuel cylinder rapidly super-cools, with a resulting drop in pressure that is 
pretty close to zero. Europe is now starting to mix butane with propane, 
playing catch up, but not doing very well at it. Catching up always requires 
'fessing up to your mistakes as a first step.

The only real innovator I have found in English heating equipment is 
Bullfinch, who not only has come up with some pretty clever single gas torch 
designs (I love their ignition system), but even appears to have its own 
foundry. However, I tested Bullfinch's biggest brazing torch against a 3/8" 
tube burner last year, and the burner won (just). When tested against a 1/4" 
burner with a much narrower target pattern, the 3/8" burner was completely 
blown away, but by then I'd got rid of the torch, so they couldn't go head 
to head. For about fifty-seven bucks you can buy a High-heat Torch (Model 
 "D" blowpipe): Made by Grobet USA, which will keep up with the 1/4" burner. 
The Model "D" blowpipe uses compressed air, to collapse a brush flame into a 
super fast (and therefore super-hot) needle flame. All this to say: 
"European heating equipment isn't worth the shipping charges, let alone the 
prices they ask."

Apparently, Europeans agree with this view, since you can find used 
brazing/forging equipment for sale on UK sites at about 1/10th of its 
original price. As near as I can tell, sales to the school system is all 
that keeps these guys in business. However, the head of a London school's 
technical department corresponded with me for a while last year, while he 
was building a tube burner and pipe forge for home use. Apparently 1/10th 
the price still didn't make local gas forge designs appealing to him. You 
can draw your own conclusions :-)
Mike P.

----- Original Message ----- 
From: "Michael Horgan" <lughaid at earthlink.net>
To: <theforge at mailman.qth.net>
Sent: Wednesday, February 15, 2006 9:35 PM
Subject: [TheForge] Chip Bed Forge

> Some years ago I made a gas forge for use at the Renaissance  Faire, 
> hiding the hot box under some black lava rock. It worked pretty well , at 
> least as a nail forge, but you could only heat one end of the bar, with no 
> pass through. Last year we used a Whisper Mama, tucked away in a 
> faux-brick forge.  Still pretty obviously a gas hotbox.  I wanted a coal 
> or charcoal fire, but the Faire site, regulated by the Army Corps of 
> Engineers and the local county Fire Inspectors wouldn't allow the "Open 
> Fire"
>
> This year we are putting together a ceramic chip forge, basically a gas 
> burner feeding the bottom of a pile of heat resistant "rocks."  I've been 
> looking at the past postings on the forge, and talking off list with Paul 
> Boulay , Rex Price, Frosty and Mike Porter, about the ins and outs, 
> advantages and disadvantages of this type of forge. Whether it can be made 
> to work with a venturi burner or if a blower is needed, what type of media 
> to use  for best heat transfer to your steel, and so on. I've also been 
> looking at the "expensive" commercial versions available in England as 
> used in the school systems,as shown in the graphics page here,  and some 
> slightly different types available in Germany,
>  http://www.angele-shop.com/catalog/index.php?cName=gas-forges-gasforges .
>
> There have been some great ideas pop up, not to mention the usual kludges 
> I'm apt to come up with. <GRIN>
>
> Mikie in particular has a great idea for a recuperative forge that looks 
> great for a commercial forging station, if perhaps a bit more than I was 
> looking to do as a portable forge at the Faire
>
> Seems like there's some interest in this, so I'll be summarizing in later 
> messages some of the stuff we've been talking about, as well as the 
> results from some experimentation I'm doing.  I've got some refractory 
> media due in this weekend so I can try to produce some results to share.
>
>
> Michael D. Horgan , lughaid at earthlink.net
> http://members.aol.com/lughaid/
> posting from
>  A BRAZEN FORGERY
> Blacksmithing and Metalwork
> Claremont, Ca.
>
>
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