Mikey98118

Forges 101

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Yup they will fit you with a curb bit here if you don't take care. On the other hand I can direct kids here without worrying that their parents will get shocked. 

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We all get the occasional reminder to keep the language G rated, we can get a bit loony toons and slip a PG coment in on occasion but I side with Glenn, he wants everyone from grand kids to grand parent to feel comfortable here

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Twenty years writing on these groups have cleaned up my language quite a bit; don't miss the nasty any :)

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Two Daughters and now 8 grandkids and a wife willing to enforce me *not* teaching them some of the things in my vocabulary...As she says "You gotta sleep sometime!"

So workarounds: "May maledictions follow this nameless thing to the uttermost depths of world slime!"  (RAH)  Or the old BSG favorite "felgarcarb". And of course almost any phrase in German sounds like you are cussing when it is said with emphasis: "Ich möchte ein Einzelzimmer mit Bad im ersten Stock!"  ("Star Smashers of the Galaxy Rangers" where it's translated as: I spotted a door behind the throne, so grab onto me and we can escape that way.")

Here; rereading your post before you hit Save helps a lot...  (but sometimes things slip through----"Das is nicht mein hut!)

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Where I usually get admonished for is when I copy & paste something with out proof reading well enough for naughty language. Proof read, proof read, proof read then hit submit.:P

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Well, probably not to them, but I personally am totally unconcerned about my chances of being inundated with the fleas of a thousand camels ;)

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So, Frosty was saying the other day, that there are things missing from this thread. Naturally, I wondered what, and immediately box forges came to mind. Frosty and I have discussed brick pile forges on this forum, but not on this thread. To my mind, a brick pile forge has the advantage of being made of bricks, and therefore being as changeable as something built of Legos; both for shape and size.

Whereas, the size and shape of what I call a box forge has practical limits tied to your choice of ceramic boards and backing bricks. Comments, disagreements, and/or questions?

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The two-brick forge

The smallest of brick forges is called the two-brick forge because most of them are built from two standard insulated firebricks that have been hollowed out, and a small hole drilled in the side of one of the bricks for a flame from a small air/propane torch to enter. The exhaust gas leaves out the front of the bricks, and the heating stock enters the forge through the same hole.

    I would suggest K26 brick instead; split bricks cemented together with Metrikote, and with their inside surfaces seal coated with it, and the side hole drilled with a hole saw incrusted with carbide grit.

The Mag-Torch MT245C is an excellent propane torch with a low cost; it can be positioned at—not in—the hole opening, where it can induce the secondary air it needs, and avoid being overheated.

Note that the MT245C has a weakness; its gas jet is only a few thousandths diameter, and easily gets plugged up from tars and waxes present in propane fuel gas keep a small glass container and solvent handy to soak it in, along with a compressed air container of the kind used to clean off computer parts, etc. to blow it clear of debris with.

 

 

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Even this smallest of forges can benefit from a baffle wall in front of the exhaust opening. A simple hard clay firebrick with a center-hole drilled through it for the stock  to be passed through will divert heated gas from the blacksmith and help to keep the forge hot.

 

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    A third brick can be used as a convenient forge stand and as further insulation to keep the forge from overheating whatever surface it is placed on.

    One of the reasons foamed clay insulating bricks became the popular choice for these miniature forges is that nearly anything can be used to shape its surface; this is not true of K26 brick. You will need a grinder with grinding wheels meant for use on brick—not steel.

    The flame hole should be drilled toward the back end of the brick, to allow the flame to traverse the length of the forge before exiting out of the front exhaust exit.  

 



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                                                                                       Box Forges

 

 

The size and shape of what I call box forges are usually limited to the builder’s choice of ceramic boards and backing bricks, although these parts can easily be cemented together; thus all such size restrictions are really due to a lack of knowledge or will.

    The burner or burners can be down-facing from the top of the forge or facing horizontally from the side of the forge and positioned near to its top.

All parts on the top of the forge need to be cemented into a solid surface, to withstand the force of gravity. Ceramic boards on the side of the forge should be cemented together, but bricks on the side and bottom of the forge should be allowed to sit trapped in the forge structure, but be not cemented into a solid surface; this allows them to expand and contract during thermal cycling.

     The forge needs a rigid bottom plate to sit on; this may be metal or a double layer of cement board. A framework of angle iron is sufficient to hold the forge parts rigidly in place, although many people prefer sheet metal; if you choose sheet metal, remember to allow joints in its structure to allow movement; otherwise, it will be warped by the forge heat. You might also consider cement board trapped in angle iron, instead of sheet metal for the forge walls.  



 

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Brick pile forges

 

Brick pile forges have the advantage of being reshaped and resized, within the limit of their tops. If the top ends up larger than the rest of the forge, no harm is done; if it ends up to small it can be enlarged by cementing more brick around its borders. Additional burners can be included by use of a hole saw with carbide grit; so much for the good news.

    Use of hard clay firebricks will make for a cold forge and a large fuel bill. Foamed clay insulating bricks were never intended for use as a hot-face; they will rapidly crumble to rubble if used this way. K26 bricks are good to 2600 F, tuff mechanically, and able to withstand the rapid thermal cycling found in forges; They do need to have their hot-face sides sealed with a good high alumina castable refractory, such as Kast-O-lite 30, or with Metrikote.

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Cellular concrete blocks

 

If you have a local source of lightweight insulating cellular concrete blocks, it can make a convenient structural choice for outer walls and subfloors so long as sufficient inner insulating layers separate them from the higher heats of forge interiors.

    However, you need to avoid the kind of cellular concrete that uses plastic based insulation in its formula; it will outgas toxic fumes.
-----------------

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Burner positioning

The most successful commercial box forge features one, two, and three burner models, with the burners on top, and facing vertically down; this position allows fairly narrow forges, with sufficient distance for the flame to mostly combust before hitting the work pieces on their floors; an excellent use of forge space.

Most amateurs don't leave sufficient hight for the flame to combust before impinging heavily on the work, and instead make the forge too wide, with their burners too far forward. All of these problems can be ameliorated by facing the burner or burners on the side of the forge and just below the overhead.

We spend a lot pf time promoting "proper" burner positioning in "proper" forge shapes (tunnel, D, and oval) that can produce a "proper" swirl of forge gases. But the fact of the matter is that high power burners with hard flames tend to create swirl whether the forge shape is round or square; that still leaves burner positioning to do badly, so don't dispare :)

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