Mikey98118

Forges 101

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Good catch Thomas I'd foolishly assumed a person would either split off the corners or use a dowel. My bad, thanks.

I cut blanks with my hole saws. If I need a blank longer than the depth of the hole saw, I drill a pilot hole all the way through and drill from both sides. If a person needs longer than that you can stack, and glue using a piece of all thread as a mandrel. Grease the all thread so it doesn't get glued into the stack. 

Frosty The Lucky.

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Yeah trying to turn a square piece of wood in the first place with out knocking the corners off is just asking for trouble. All you need is one good catch to catch you off guard for that tool to go flying out of your hand and stick in your neck!

Although safety is paramount, it's not always the first thought.

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High alumina kiln shelves

High alumina kiln shelves are hard to beat for external baffle walls, and for internal movable walls; They only get tougher at incandescent temperatures. The kind of small round kiln shelves you might want to build either structure from is economical, and much of the work is already done for you. High alumina kiln shelves are seven times more insulating than clay based hard brick. Cheap carbide or diamond coated, burrs, blades, and hole saws from Harbor Freight Tools and eBay make drilling, cutting, and grinding on them nearly as simple as working in metal. So, a round kiln shelf can be mounted on home made hinges, given a latch and a small opening to shove parts through, and made to serve as the perfect baffle wall, allowing you to heat bulky shapes, like hammers, or crucibles at will. Or the shelf can be trapped in three short angles that are mounted to the forge shell, so that baffles with various openings can be changed out, accommodating different work pieces with minimal openings for maximum radiant reflection. A less obvious but just as useful feature of high alumina is that it provides  a tough supporting surface for stabilized zirconia flour/bentonite clay based heat reflective coatings.

I consider hard fire brick as useful for temporary baffle walls, allowing the forge to work at bending parts for permanent upgrades of add-on structures.  

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I also recommend high alumina kiln shelves in tube forges, where they are suspended in the shell, with only ceramic blanket underneath. Part of the reason for using a shelve is its strength, which is needed for a suspended ceramic part. In a box shaped forge, the floor rests directly on the forge bottom, or on a ceramic board, which in term lies on the forge bottom. So, the part will be completely  supported. In this case the money is better spent by purchasing Kast-O-lite 30 refractory from Wayne. In an oval or "D" forge, where ceramic board is best used as floor insulation, I would choose high alumina refractory for the hot-face.

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I/4" high alumina tiles source

scrambler88 has found another source of 1/4" high alumina tiles.

They can be used like kiln shelves in coffee-can forges, and as a physically tough hot-face material to help protect ceramic board insulation in box forges!

8” by 8” by 1/4” high alumina tiles: http://www.euclids.com/index.php?item_id=F88XX

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I was thinking what a great flame face 1/4" tile would be for internal movable baffle walls for two and three burner forges, which brings up thoughts on how to buiid them with insulating layers that would be needed anyway to keep them wide enough to remain upright, and it brought up, once again, how handy a hinged front face on forges are.

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Some things are an essential part of building or relining your forge. Other things are what I call an add-on. For instance, nearly any external part can be mounted on a forge shell, at a later date, and burners can be changed out; ditto for hot-face coatings, or in this case, armor coverings over other refractory products. 

1/4" thick high alumina tile can do similar things on your forge walls, that the kiln shelve does for a floor; it isn't needed for protection against hot flux there, but provides armor against bumps. It should not be needed for protection against direct flame impingement, as is likely to be necessary at times on the floor, but will prove a similar benefit as the shelve, in lessening thermal wear and tore on the underlying insulation. In fact, I figure that ceramic board, plus tile, plus heat reflective coating, should work out supper fine in a box forge.

Of course, that tile will become a heat sink, but it should prove to be a minor one, because it's very thin; say an extra five minutes heat up time . Of course it means time and money spent, just like a heat reflective coating costs time and money, but like that coating, it needn't be an immediate, or you're busted thing. On the other hand it should make a permanent part, unlike the consumable board it protects. You can even paint the heat reflictive coating on the board first, and add the tile over it later; the first coating will still serve some purpose next to  the tile's cold-face, although you will get maximum benefit by coating the tiles hot-face too :D 

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When and why NOT to choose a coffee-can forge

There seems to be some confused ideas about coffee-can forges being a cheap way to get into heating up metal. What they are is an economical way to forge small parts after the forge is built; the economy comes in minor fuel use. They are also highly portable and compact tools, for those with limited space. The only savings encountered in their construction will be in the economies of scale. You can find ceramic wool blanket offered in squares that are large enough to work in a C-C forge, so you spend less money for it. But, those offers are also a rip-off, so far as how much you end up paying per square foot. Mixtures of Perlite and water glass are going to melt in short order. Perlite and furnace cement are going to back down more slowly, but they still cannot hold up to forge temperatures. You would need Perlite and castable refractory to do the job, and then you have just lost enough money to by that square of ceramic wool blanket. The infamous plaster and sand 'refractory formula' is such a major heat sink that you will end up throwing you forge in the garbage before the so called refractory has a chance to disintegrate!

The second cheap and easy idea about C-C forges is that you can run them with propane canister-mount torches; yes and no. There are only a few very high priced propane torches that have stainless steel flame nozzles, and their nozzles are so thin that they will quickly oxidize away inside of a forge. Most of these torches have brass nozzles that will melt inside of a forge. So, the torch cannot be placed in a sealed burner port. Instead, it can only be placed in an oversized hole, if it is weak enough, or aimed toward the hole from outside of it, if it is one of the hotter models. Anyway you go, either the torch is destroyed of the forge is under powered.

So, you need a real burner. But, if you're going to the trouble to build a burner, you want it placed in a forge that is worth it, right? Now you have another problem, because a 3/8" burner is the largest size you can use in a C-C forge, and the only one you can build is a Mikey burner; it can be found in the Burners 101 thread, but by the time you've constructed it, you won't want to waste it in a forge you just built to save money! There are plenty of burners you can build in the 1/2" size, if you're willing to put them in the typical mini-forge (built from a non reusable Freon of helium cylinder).

Coffee-can forges have their place, but trying to use them as a cheap and easy way to heat steel, is crazy; that's what charcoal if for.

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When I built a 1 soft firebrick propane forge it was specifically made to be able to use it to forge in my basement during an Ohio winter. In it I made nails for my Mastermyr chest and hot forged silver for Viking jewelry.  As soon as it was warmer I went back outside and used my propane and coal forges for doing some "real" smithing.

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Thomas,

If you wouldn't mind going into your brick forge more, there are apparently even more guys interested in making two brick forges than coffee-can forges. You may have noticed that I have nothing against C-C forges; I am personally interested in them (and in C-C casting furnaces). I spoke up out of concern with the fairy stories being circulated on YouTube. A bunch of disappointment makers will do nothing to promote heating equipment. Down to earth accounts of what miniature forges actually require, and can do, is sadly lacking in the community. I am all for as much variety available in burner and forge choices as possible--so long as people build them with their eyes wide open; not sticl shut with B.S.

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There's an interesting little two-brick forge in this charming little video about a jaw harp maker in St. Petersburg.

I don't know what kind of torch he's using, but it's interesting how the two bricks aren't attached together, so that he can lift off the top to place his stock right where he wants it.

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On ‎5‎/‎28‎/‎2017 at 4:32 PM, Mikey98118 said:

I am waiting for an answer back on prices. "A salesman is going to call."

Mike, did you ever receive an answer?  I can't, for love or money, locate anything regarding pricing on their site.  Their order form even has a blank to populate.  :wacko:

Their claim regarding the 311 foam blocks, "2000ºF, white hot, parts can be immersed in water with out cracking.", sounds awesome tough.  As a material resource for work, I've just got to have some to trial.  I can envision a forge for our tool fab shop....

 

 

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I think that's an oxy-fuel torch; probably oxyacetylene, since big insurance companies aren't allowed to dictate life through government agencies in the Mideast. The guy definitely has everything down to the essentials. That looked like a cutoff disc in a 4" Makita angle grinder too. He uses a very hot flame in a very small space to heat the work with a minimum of heat and time wasted; smart!.

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2 hours ago, Mikey98118 said:

big insurance companies aren't allowed to dictate life through government agencies in the Mideast.

Well, St. Petersburg isn't exactly the Middle East. 

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It was a dark and stormy night....well it was mid winter in Ohio and tough to stand in the snow and forge small cross sectional items when the anvil keeps trying to be below freezing to match the ambient.  However my 100+ year old house had a full fieldstone basement with a lot of ventilation---you could watch the curtains move near the tiny windows up near the ceiling.  But it was more like in the 50's degF down there and my small anvil, 91 pounds, was already down there.

So I took a single soft firebrick and drilled two 3/4" diameter holes from the small end of the brick about 3/4 of the total length.  I offset them slightly so I could take a piece of hacksaw blade and saw out the section between them leaving a slot.  Then I drilled a cross hole through one side of the slot about 2/3 the length of the slot from the open end and towards the top of the slot.  The size of this hole was based on the cheap brass propane torch I used.  Now in use the propane torch does NOT enter the cross hole but remains just outside with the flame going into the brick.

With this set up I forged the appx 40 nails I used in my Mastermyr chest.  I also used it to hot forge silver for viking style penannular brooches and other various hacksilver items.  It was very nice to sit in the basement with my anvil between my knees hammering away while outside the storm rages...

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Thanks for that account Thomas. I see the similarity between the brick setup in the video. I have used firebrick in the past, creating some deflection in oxyacetylene flames; that was done to use cutting tips to forge steel parts. That was in my youth, and long before ever considering gas forges.  Maybe the problem starts in the word "forge"; essentially that is what it is, but it is radically different than what comes to mind when most of us think of one. There would need to be two essential differences from a standard gas forge, for this idea to work:

First,  a really hot burner design must be combined with a hotter fuel than propane; propylene would serve that purpose.

Secondly, a high alumina castable refractory molded shape would need to replace the brick; something good to about 3400 F, with the burner port molded in, including a built in flame nozzle.

But, do people want it enough to do what it takes to construct one properly; and what to call the thing? Really tiny forge? Sub miniature forge? Nail forge?:wacko:

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Clam Shell Forges

What is hard about making clam shell forges? Nothing, wants we get past the idea that they are somehow mysterious; they're not. In fact they are one of the easiest forge shape to make. Like every other forge, the first question is "how big?" And like every other forge the answer is "what for?" Whether you want to pound on sheet iron, or work on scrolls, area needed equals area to be worked. Unlike any other forge this area is two dimensional; not three. Height of the forge is variable, as brick is used around the periphery of the forge, so height can be varied at will. Also exhaust openings are provided by openings left in the brick wall.

The forge top is provided by any convenient sheet metal form, from a wok to a garbage can lid. My clam shell's top was part of a barbecue. Into the lid is placed two or three 1" thick layers of ceramic fiber blanket. Each layer is rigidized with fumes silica, and flame hardened, before the next layer is installed. The slight dish shape, combined with the gluing effect of the rigidizer leaves the insulation quite able to maintain itself against gravity. There is no need to use a ring to hold the insulation in place. just use sheet metal screws all over the  the lid's top, reaching down part way into the insulation, which is now glued together; it can now longer de-laminate. It's a good idea to finish the blanket with a finish coat layer.

The forge base is basically nothing more than a table top, with insulation and a flame face (hot face) layer. Chapter 6 of Gas Burners for Forges, Furnaces, & Kilns (free downloads from the net),  shows how to build a "forge cart." It is actually an insulated hot work cart, with a builtin burner. The clam shell forge top is simply included in it. You could can do as little as line the top of a steel cart with bricks for short projects, are build a dedicated cart.

The forge top is held in position with a pipe within a pipe, that can be raised to a desired height, and held there with a tightening bolt. A seesaw top piece on the top of the inner pipe holds a wight at one end, and the forge lid at the other.

Obviously, you can mount one or more burners in refractory burner blocks, positioned between the bricks, with an exhaust hole in the forge lid. Or, you can allow exhaust openings in the brick and mount a burner in either the lid, or the table top.

 Of course, table top mounting invites building in a ribbon burner, which can only be the very best choice for any large clam shell forge, and since it is built in to a cart, other tops, and brick piles can also be used on it :D

 

that should read "fumed silica"; not fumes silica .

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Small clam shell forges are even simpler to make, as round high alumina kilns shelves are cheaply acquired from any pottery supply store. a Pair of them can become the hot faces for the forge top, and forge bottom, with layers of insulation trapped between hot face and and sheet metal lid, pan, dpg dish, etc. Carbide encrusted hole saws from Harbor Freight Tools are a cheap and easy way to install a burner or exhaust opening in top or bottom shelf. Such small forges are thrifty to build and run, and are portable. A standard small naturally aspirated burner is all they need.

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Thanks Mike, that's a pretty concise description of what a clam shell forge is.

Ironforge: Now all we need to know is details for what you need.

Frosty The Lucky.

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Secondary Air: Merely Bad or outright awful?

Even properly calibrated neutral flames in oxyacetylene torches produce secondary flames, so it is hardly a wonder that most air-propane burners do too. Over the last twenty years, ever more burners were designed to produce ever smaller secondary flames, and a very few burners don't need to produce any secondary flames at all. Without getting deep into burner theory, the one central fact about secondary flames, which you need to know, is that they must combine with ambient air to burn; that means that the higher the amount of your burner's fuel consumed in secondary flames the more secondary air is needed in your forge.

Forget the idea that secondary air can slip into the forge from the exhaust opening; that simply isn't going to happen in a well regulated forge. The secondary air your burner needs comes into the forge through the same port your burner does; it is induced into the forge by the flame, just as primary air is induced into the burner by the gas jet in any naturally aspirated design. But even if you have a fan-blown burner, it's flame can induce secondary air into the forge, if the burner port isn't sealed.

At best, secondary air is a necessary evil. Excessive secondary air, is where "outright awful" comes into the picture.

Burners with little or no secondary flames, tend to be high speed burners with very hard flames. Frosty's "T" is the only exception to the rule thus far. Hard flames also induce more secondary air than soft flames. Burners with hard flames induce so much secondary air through the typical burner port that sealing them with ceramic wool can jump internal temperatures up 20%, or allow you to cut your fuel consumption back that much. Ironically old burner designs need more secondary air on the one hand, while their soft flames induce less of it on the other, so in the past, sealing burner ports wasn't practiced.

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How to update the hole in a a refractory or brick wall, if you neglected to build a proper burner port

The easiest way to build a burner port into an existing furnace or forge, is to use a pipe or tube that will fit snugly into the burner hole, and cut slits down the length of the pipe or tube, for the distance that it is inserted within the refractory. This will prevent the metal from cracking hard refractory or fire brick, as it expands. The outside portion of the tube contains six thumbscrews to support and aim the burner, and a washer that can be used to control the flow of secondary air into the furnace.

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To shade or not

"What kind and specific type of shaded safety glasses do you recommend?" This question comes up more with casters and hot glass workers, but if you have a very hot running forge, it may cross your mind.

Safety glasses lower visible light (glare) and UV. With the single exception of oxy-hydrogen flames, which have no carbon atoms to absorb the UV being generated, It takes an electric arc or a minimum 6000 F flame temperature to create a UV hazard. You are much better off looking for a lite shade of welder's safety glasses, or if you feel rich, glass blowers glasses; both kinds reduce glare and infra red, which this work does generate. Unless you want to trick up your own safety glasses, you won't find one with a lighter shade than 2. So, how do you avoid glare, and maintain a good view of the work?

No matter what kind of shades you employ, they all have one thing in common: from welders goggles to sun shades, they are formulated to admit more green light, than every other part of the spectrum combined. LED lights put out all of their energy in vary narrow color bands, so a green LED light shining down on your anvil will give a very nice view for minor wattage, and no heat gain.

 

Also for very minor money.

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By welders glasses he is referring to the ones sold for oxy-acetylene welding and NOT arc welding.  Remember that most people do not know anything about smithing and I've know a number of smiths told they needed arc welding masks for basic forge work IN ERROR!

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