NJBA --The New Jersey Blacksmith Association

• Visit our website at NJBlacksmiths.org

• View our 24-year archive of Newsletters, with searchable index at NJBlacksmiths.org/archive.php

• Visit our subreddit at Reddit.com/r/NJBA

Problems with Forged Work

Cracks and Cold Shuts

This was a response to a posting that showed a photo of a pair of tongs, newly forged. The closeup of one jaw showed something at base of nearer jaw that might be a cold shut (a crack). If it is a crack, the tongs WILL break there during use.

Grind the Crack

If this describes any item you have forged, take a close look at the possibly crack. Sometimes it will prove only to be a break in the scale. If unsure, LIGHTLY grind the area to see if it's a crack that goes below the surface. If so, grind it out till no trace of the crack remains

Grinding away a crack (removing as little metal as feasible) actually will make the piece stronger. That may seem counter-intuitive but is true for most materials. Consider how a seamstress rips her fabric -- one little snip at the edge, then it will just rip apart. And fabric is particularly resistant to such tearing due to the individual fibers that compose it. One tiny crack in a piece of steel under stress will propagate through the piece till it fails.

Origin of Cracks and Cold Shuts

If this proves to be a real crack, it likely arose from working the metal too cold -- especially near a change in cross-sectional area, as in this photo. When working on either side of such a transition, ALWAYS keep the area of the transition at a red heat, at least. At such a heat, cracks are much less likely to form, whereas at a "black" heat they are much more likely to form. Transitions such as those between a spoon bowl and the handle or a leaf blade and the leaf stem are particularly subject to cracking.

The other major source of cold shuts is folding steel over steel without welding the two together. It may not be obvious that this can easily occur when forging an inside corner: Always forge an inside corner with at least a small radius. If you forge an inside corner perfectly square you will very likely get a cold shut at that corner.

Cracks and cold shuts may not matter on strictly ornamental pieces, but even pieces such as weather vanes can vibrate and vibration can lead to failure at cracks, even if there is no other load on the piece.

Why didn't my weld take?

The usual reasons for that are

1. The metal wasn't clean enough and/or the flux didn't carry off the oxide.

2. You welded at too low a temperature.

Here's a trick that may help: Take a 2'x1/4" rod and forge it out to a sharp point. Use that as a tool for welding. Get your workpiece(s) up to a welding heat and touch this rod to each part to be welded. If they're at a welding heat, the tip of the rod will stick to the part (it actually welds onto it, but is easily tugged back off).

Also remember to have everything ready to go before pulling your work from the fire. Missing a hammer when you need it just wont cut it.

Your first blows should be light -- just enough to make the weld stick. Don't fear reheating the piece immediately after welding and before working the weld further. At too low a temperature you'll never get a weld. Reflux before reheating.

Borax as Flux

Borax is probably the cheapest and most readily available flux for the beginner (at least in the USA -- as I hear it's hard to find in Europe). The problem with borax is two-fold:

1. It contains a LOT of water (called "water of crystallization" -- it will feel dry).

2. It can be hard to get rid of later/

The latter is not a big problem if you're not doing commissioned artwork.

Because of the water content, it foams when applied to hot metal, and this foaming cools the metal. Hence I recommend heating the metal to cherry red before applying borax flux. This caveat does not necessarily apply to the several proprietary fluxes a blacksmith can buy.

Learn proper hammer technique.

• Grip hammer loosely.

• Elbow should almost brush the side of your torso.

• Keep flex of the wrist to an absolute minimum, working instead from elbow and shoulder.

• Bring hammer face down flat on the workpiece -- don't angle it except in those instances when you mean to angle it.

• Practice by hammering scrap lumber and observe the hammer marks -- flat face marks, not edge marks.

• When swinging from the shoulder you should be able to shatter lumber within several blows -- which is one way to make kindling.

And ALWAYS wear safety glasses when hammering. The energy of hammering is enormous. If something (wood or metal) shatters and flies in your direction it can take out an eye.

Suggestions for Wannabe Knifemakers

Don't try making real knives without first learning the basics of blacksmithing. This is "crawl before you walk, walk before you run."

Knives require medium-to-high-carbon steel, which is harder to work and may crack if incorrectly quenched. Before your rough forging becomes a real knife, you need to heat treat it -- again, properly. At some point in the process you'll need to grind the edge.

All of that is in addition to being able to forge the blade to shape in the first place.

So, do yourself a favor and first learn the forging operation. Then maybe the grinding operation. Do those using mild steel, which is cheaper and easier to work. If you can't forge your shape from mild steel, you certainly can't forge it from medium or high-carbon steel.

Once you have those mastered, you can move on to learning proper heat treatment of steel. Learn this on dummy pieces of medium or high carbon steel -- don't waste effort forging a knife, only to ruin it in the heat treatment.

Finally, put together what you've learned and make your first real knife.

Blacksmith Information and Education

Books I Recommend

(This list is incomplete. I'll be adding to it from time to time.)

1. Alexander Weyger's The Complete Modern Blacksmith (~$20) -- he'll show you, among other things, how to make a coal/charcoal forge that doesn't even need a blower, three ways to harden and temper tools, etc.

2. Jack Andrew's New Edge of the Anvil.

Blacksmithing Videos

I don't know whose list this is, but found it posted on a Reddit blacksmithing site:

• https://docs.google.com/spreadsheets/d/1FYC0dbJlaWk6wIddDK_WIx4-gSwggoun93LLfeVnX_g/pubhtml?widget=false&chrome=false

Book Reviews and Excerpts

Safety and Personal Protective Equipment

Save Your Eyes

Wear eye protection, preferably goggles, when:

• using a power grinder, especially an angle grinder

• using a wire brush, especially a power wire brush

• using a buffing wheel

• using hammer and chisel, or a hammer and any struck tool

• forging

• using any chemical or substance that's not safe in your eye (e.g., mineral acids, lye, bleach, toxic substances, grit.) Water is safe in your eye, and even that hurts.

• using just about any rotary power tool that might kick something in your direction (e.g., a line trimmer, a leaf shredder, etc.)

You may "get away with" not wearing goggles when using a drill, a drill press, a mill, a lathe, a power lawnmower, etc., because these seldom will direct the swarf or other matter toward your eyes, but even then it is prudent to wear some sort of Z87 glasses.

When you finish up a bit of work, take off your glasses or goggles and notice tiny shrapnel embedded in them, you gain a better respect for the reason you should wear them.

What Personal Protective Equipment Should I Use?

At a minimum, Z85 glasses or preferably goggles. Harbor Freight and other vendors sell goggles that fit over standard glasses and provide protection from all directions.

If dust is your concern, a dust mask. Generally speaking you don't need anything as sophisticated as an N95 mask. I consider a bandana suitable for the grinding I do, though I usually use a cup-type dust mask for the convenience. A bandana has the advantage of covering the beard. A full-face shield could be used, but not as a substitute for the Z85 goggles.

Note that most dust masks and respirators are not really compatible with beards. Dust and vapors can get under the mask along the tracks of the beard hairs. Nonetheless masks will provide protection from all but the smallest particles (those that float like smoke particles). The only truly safe respirators for use with beards are supplied-air respirators -- which cover the whole head and bring air in with a pump through a filter. My experience says this level of concern is not needed -- for the grinding I do. It would be a different matter if I wanted to filter out toxic fumes.

The Angle Grinder

...a.k.a. ye olde flesh eraser.

NEVER wear gloves when using an angle grinder -- or when using any wire wheel or buffing wheel regardless how its mounted. The wheel can grab the glove and your hand goes along for the ride. Not fun.

I'm an advocate of cheap is good enough for tools such as these. By buying cheap angle grinders I can have a half dozen of them on my wall, each with a different wheel -- grinder, cut-off, flap disk, wire wheel, wire cup brush, etc.

It's up to you how much you spend, but, not being in this as a business, these cheap grinders work well for me. Yes, I've burned out a few, but even so I've spent far less on these cheap ones than I would have had I bought professional quality tools. For a professional, such tools are important. You don't want to be left "high and dry" if a tool fails while you're on a job. But in a shop, where you can have spare tools, this is not such an important consideration.

The Dead-Man Switch

Lawnmower now have a lever (or equivalent) that, when released, stops the blade within 3 seconds (so they say). I know of no such feature on any angle grinder, but many do feature a "paddle switch." You hold the paddle switch to grind, and if you release it, the grinder coasts to a stop. (I have a chunk of wood secured by my workbench, and I bring the wheel up against this to stop the spin more quickly.)

The other extreme is a simple on/off switch which does NOT flip to "off" when you release it. Clearly these are more dangerous. Nonetheless, I use such (cheap) grinders for most of my work. I use grinders with paddle switches with wire wheels -- which pose a higher level of danger.

Blacksmithing Equipment

Hammer Type and Weight, Hammer Grip -- and Tendonitis

You should not grip a hammer handle tightly at all. If the hammer doesn't fly out of your hand, that's tight enough. On the back swing, another person should be able to pull the hammer right out of your grip, no contest.

Also, use a light hammer. 1.5 lb is fine. Rarely you'll need a heavier hammer -- like for some upsetting operations or for very thick stock -- but not all that often. Using a 4-lb sledge routinely is a good way to have a very short career as a blacksmith. You can't forge at all once the tendonitis gets you.

It may seem macho to use a heavy hammer (and it is nice to be strong enough to do so the rare instances you need to), but you'll accomplish twice the physical work by using a hammer half as heavy and swinging it twice as fast.

You'll see a number of different styles out there: French, Swedish, etc. Ignore those, initially at least. Later you can explore their relative advantages.

For a novice there are three issues of importance:

The 3-D shape of the hammer face,

The weight of the hammer (head), and

The length and overall comfort of the handle.

Some commentary:

Hammer faces may be flat, curved in one dimension (e.g., straight pein or cross pein hammers), or rounded (i.e., spherical, e.g., ball pein or rounding hammers). If you strike a hot workpiece with a hammer, the hot metal will move away from the blow in all directions, but slowly. If you use a ball-pein hammer, the metal it moves in all directions much faster; or use a rounding hammer for intermediate effect. A rounding hammer also has uses like forming the inside curve of a horseshoe. In contrast, a straight pein or cross pein hammer moves the hot metal mainly in only one direction, which is good for drawing out a workpiece either long or wide -- but not both. Be aware that regardless of the shape of the hammer face, the edges as they come from the factory are typically sharp and not suitable for forging and must be "dressed" -- i.e., rounded slightly to eliminated the sharp edge.

Novices tend to use hammers that are much too heavy. I see discussions about 4-lb hand-held hammers here and cringe. There are some uses for such heavy hammers, upsetting in particular, but if you always use a heavy hammer you're likely to develop tendonitis -- and have to take a prolonged break from forging at all. It's your choice. I suggest using a 1.5-lb hammer routinely, and using a heavier or lighter one as necessary. Yes, I know you're macho and can swing a heavier hammer. I'm not impressed. So can I. (Wanna know how I swing a 16-lb hammer one-handed?)

The handle should be comfortable and of such length and thickness that you don't have to chock up excessively and you can grip it comfortably without gripping it tightly. Avoid cutting gouges or such in the wood as these may cause blisters. (To each his own.) Light sanding of the handle to keep it from getting slippery is fine. This is an issue in which "if you ask ten blacksmiths you'll get a dozen answers." The main consensus is that you shouldn't grip the handle too tightly, and if you have to, something is wrong.

Your First Anvil

Harbor Freight and similar vendors offer a 55-lb anvil for about $65 or so. It's not like a Fisher-Norris anvil: cast iron with a steel face. I was under the impression that it was cast steel, but a correspondent asserts it's actually cast iron. (I will have to do another spark test.) In any event, its face is so soft you can cut it with a file.

I hear there are better ones for the price, but I've never seen one of them. Read through postings on this Reddit.com:-- /r/blacksmith and r/blacksmithing -- for such discussions.

NJBA has six of these that we use for demonstrations and for open forge meets. We got them mainly for the price -- about $60 at the time. A high-quality anvil of about the same weight would have been about six times as expensive.

As the late Roger Duncan (of 00Fe fame) used to say, "That's a better anvil than you are a blacksmith."

You can make yourself a hardy plate to compensate for the soft face and the edges that won't last. Meanwhile it will get you started.

This is not to say you should not keep looking. Always look. Scour Craigslist, garage sales, farm sales, flea markets, etc. You can pick up a lot of good stuff there. Maybe even post a (free) Craigslist ad, "anvil wanted by aspiring blacksmith." There ARE anvils out there.

A (late) friend of ours once got a 250-lb anvil for FREE for hauling it out of a widow's basement. (Hell of a job, but worth it.)

And there's no reason you need an anvil-shaped object. You mainly need a heavy, hard surface to hammer against. Rock isn't great because it shatters, so steel is the best choice. Look for forklift tine, thick steel shear drops, and other massive metal objects.

Pointers for Builders of Treadle Hammers

An Oliver hammer is one of the simplest treadle hammers and consists of a sledge hammer mounted on a pivot, held up by some sort of spring, and typically motivated by means of a treadle.

I am the inventor of the Grasshopper Treadle Hammer, a hard-hitting hammer with a "weightless" (i.e., balanced) ~75-lb ram, a largely unobstructed 250-lb anvil, and a long (~22"), vertical stroke, and an adjustable treadle (for accommodating tooling atop the anvil). In the process of developing this hammer, I learned a lot about treadle hammer design, and some of it I pass along here.

Springs -- Balancing the Hammer

It is best to use weak springs that are about half-extended by the weight of the hammer alone, but have sufficient stretch to allow the hammer to hit the anvil.

• Weaker springs have lower spring constants, so stretching them further takes less effort, and

• Stout springs like garage-door springs are under tension even before they begin to stretch. You have to work to even start to stretch them.

• The spring force you need depends on the lever-arm it acts upon. By extending the lever arm further from the pivot, you can go with weaker springs, and vice-versa. This give you some flexibility in the choice of springs.

Choice of Springs

Caveat: Run a slack safety cable through the spring, long enough for the spring to stretch as far as necessary, and firmly attached at either end. When springs snap, it can be ugly.

Spring force is generally described by the equation

f = k * x

where:

• f is the force exerted by the spring,

• x is the extension (or compression) of the spring from its relaxed state, and

• k is a constant, different for different springs, known as the "spring constant."

Here are the considerations:

• The stronger the spring, the greater the force per distance the spring is extended.

• The spring force must balance the weight of the hammer when the hammer is fully raised.

• Ideally, the force needed to bring the hammer down to the anvil would be small.

• This can be achieved if the springs are weak.

• For weak springs to hold the hammer fully raised, they must already be stretched significantly.

• I don't have any particular recommendations for springs, but a rule of thumb is that the thinner the spring wire and the larger the diameter of the spring coil, the lower the spring constant (i.e., the weaker the spring).

Avoid pre-tensioned springs, like garage door springs.

• If the coils touch when the spring is not under tension, then it is highly likely that the spring is pre-tensioned.

• You can demonstrate this yourself by hanging one from an overhead beam and hanging weights from the other end till the coils begin to separate.

• You have to overcome that pre-tensioning before your hammer will even move -- a total waste of your energy.

• Garage-door springs are not a good choice both because they are pre-tensioned and because they are strong -- i.e., have a high spring constant.

• So just about any springs are better than pre-tensioned springs.

• However, if springs you're using are already stretched (coils separated) when the hammer is in the up position, then you've already accomplished overcome the pre-tensioning, and the only remaining issue is the spring constant.

"Kickback"

• If the hammer won't bounce back up when it strikes the workpiece, the solution is not to use stronger springs.

• Rather, when using the weak spring, add another small spring on a loose cable, such that this extra small spring doesn't start to stretch till the hammer is at full velocity and fairly near the anvil.

• The little extra oompf provided by this small spring will accelerate the hammer upwards,

• And it will do so without adding much load to your leg because by the time the cable tightens the hammer will have significant momentum.

• I call this effect "kickback."

Counterweighted Treadle Hammers

I've seen photos of such hammers, balanced like a playground "see-saw" (or "teeter-totter," as it's called in some regions). I have experimented a bit with the concept. The big problem I found is that gravity is a relatively weak force compared to the forces achievable with springs. The result is a fairly slow return stroke. I leave this for other inventors to solve.

Anvil Mass

Maximize the mass of your anvil, within reason. My treadle hammer design uses a 250-lb, 6" round (about 30" IIRC) stood vertically. You don't have to go that heavy. If you can, rig your Oliver hammer to work over your usual anvil.

Treadle Linkage

• Use a chain linkage and a spring link (carabiner) to adjust your treadle to the lowest possible height that will bring the hammer to the anvil or to the tooling you're using atop the anvil.

• There are other ways to achieve the same adjustability, but this is the simplest.

• If your hammer stroke is very long, consider increasing the motion of the hammer versus that of the anvil by changing the placement of the cable to the hammer arm.

Forge Burner Types

Aspirated Burners

Aspirated burners require no supplied air and, hence, no electrical connection. These have an orifice in line with the bore of the burner tube and an inlet for ambient air nearby. The velocity of the gas entrains air to produce a combustible mixture. The better designs have some means of adjusting the air to fuel ratio.

You do not blow air into an aspirated burner.

Aspirated burners mix gas and air intrinsically. No other devices should be needed to effect complete mixing. In particular, avoid using elbows as these create back-pressure, which can adversely affect burner performance -- the propane stream is the only impetus in these burners.

Generally, to work properly, the orifice of an aspirated burner must produce a stream of propane directed to the center of the burner tube. If misaligned, the burner generally will not perform.

Blown Burners

Blown burners require an air blower but no venturi or other such device, though they often have elbows or swirling vanes to mix gas with air.

All Burners

When a burner is used outside a forge, a flame holder may be needed to keep the flame at the end of the burner, lest it blow itself out . A flame holder can take any of a few forms, e.g., an expanded burner end (slowing the flow), an outer sleeve around the end of the burner (which I believe entrains additional air -- but I haven't looked into it), and possibly other designs.

A flame holder is not needed in forges that use mineral wool as insulation because that acts as a glow plug, continuously reigniting the gas mixture. I've never used a flame holder on my forger burner.

How high should your anvil be?

It is oft repeated that a good height is when you stand straight with you arm at you side and your knuckles touching the anvil. That is the "common wisdom." If this height works for you, fine, go with it. But there's no magic about it. This height suggestion comes from old blacksmiths who did heavy work with the aid of a striker. When swinging a heavy hand-hammer or a sledge hammer, you don't want the anvil very high -- just high enough that the hammer lands flat on the face of the anvil.

For much work that amateur blacksmiths will do, this height suggestion is too low by 6" or more. In this case, it is more important not to be leaning over the anvil. Consider going the other extreme: What is the highest the face of the anvil can be that still allows you to strike the face square and flat?

In other words (in my experience) the anvil should be high enough that your back doesn't give out from bending over.

What Do I Need as an Anvil?

Albeit that there are legitimate uses for anvils of 300 lb or more, the beginner should not waste his money on one. If it comes cheap, go for it, otherwise, don't bother.

For general blacksmithing a medium-weight anvil, say 125-150 lb, is nice to have. It's still "portable" in that one man can carry it, or certainly can move it around on a hand truck, but it's got enough mass for most amateur blacksmithing, and much professional work as well.

However, for a newbie I recommend getting a cheap anvil of any sort they can find. The late Roger Duncan (of 00Fe fame) sold his wares from a trailer featuring a cheap Chinese anvil, and would comment, "That's a better anvil than you are a blacksmith!"

For our portable equipment, NJBA uses Harbor Freight 55-lb anvils. Tjese are very poor quality anvils, but for open forge meets -- for beginners -- they're fine. I've heard some vendors sell better anvils in this weight range, but I haven't seen those myself.

Why Does One Coat the Inside of a Gas Forge with a Refractory Cement?

There are two reasons I know of for coating the inside of the mineral wool insulation.

1. To provide a more rugged surface so as to minimize the particulates that might arise from the mineral wool.

2. To reflect the radiant heat back into the forge.

The former reason has been much discussed here. The case for stabilizing the surface is that, after the mineral wool has been subjected to forging temperatures, it can fracture into "dust" of very small size. Particulates in the lungs will cause damage, but it is (in my opinion) equivocal whether they will cause cancer.

It is very true that mineral wool will fracture, but I do not myself know that it fractures to small enough size to be a concern. It makes sense to coat the mineral wool just to minimize the fracturing (and resulting degradation of the insulation), but I reserve judgement whether there is also a health benefit.

One confusion that occurs is between mineral wool and asbestos. They are not the same thing. I happen to think mineral wool is less of a risk than other people do, but each user has to make his own mind about it. It is not up to me to decide what you should do to protect your health.

The latter reason was one of the earlier ones touted for coatings, The proprietary coating "ITC 100" was reputed to reflect a considerable portion of the heat and therefore to reduce gas consumption and/or improve forge performance. I have not myself seen the evidence, but I don't mean to dispute the claim.

My Propane Tank is Frosting up -- I Can't Get Enough Pressure Through my Regulator

It is not uncommon for a 20-lb propane tank to frost up (water from the air freezing on the outside) during use. When this occurs, the propane will be at a much lower pressure inside the tank, choking off the burner.

Just place the propane tank into a wash tub of room-temperature water. The vastly greater heat capacity of the water will more than suffice to keep the propane near room temperature.

The better solution is to get a larger tank, but that option is not open to everybody.

Active temperature control systems are more subject to failure than passive ones. If a thermostat failed with heat still being applied, tragedy could result.

A wash tub of RT water is an easy remedy to tank freeze-up. So long as the tank is removed from the water between uses, there's not too much that can go wrong with it. You might want to ensure the tank won't tip over in the tub, but that's easily done.

Flues -- What size do I need?

When venting a forge hood, ignore the folks who say you can't do with less than a 12" flue. I once got excellent draft from a 6" flue -- about 16' tall to clear my shop roof. Our group uses 10" flues of maybe 8' height all the time. I've used an 8" flue of 4' height outdoors many times -- they're not as efficient and I'd want a taller one for indoor use (and would certainly need a taller one just to clear the roof).

Basically, the taller the better, within reason. The larger the diameter, the less resistance to flow -- BUT the more air has to be heated before it begins to draw. (If a forge flue doesn't draw, roll newspaper as a torch and hold the flaming torch at the bottom of the flue. It will then draw nicely.)

Read up on how high a flue should be above the peak of the roof -- that's important as well. I think 3' above the peak is needed.

Firepots and Economizing on Coal

A good firepot is 3/4" thick cast iron. Cheap ones may be only 1/4" thick. Overheating a thin pot can lead to its failure. (Using water on a hot cast iron pot is almost a sure disaster.)

You can get away with a 1/4" thick steel fire pot -- i.e., one you weld up yourself as I know of no commercial such pots. (If anyone needs plans for such a pot, message me.) However the only advantage of such a thin pot is its light weight. If you're going to weld one up, consider using 1/2" steel -- if you can cut it.

As to reducing coal consumption, the best way is to keep your air blast to the minimum you need. A newbie's error is to use an electric blower and to leave it running full blast all the time -- burning up coal to no avail.

Insulating a Firepot

I wouldn't have thought it necessary to mention this, but the question was asked by a beginner:

It is completely unnecessary to insulate a coal firepot and would be counterproductive. The insulation could not go between the pot and the coal. Firebrick would be a clinker magnet. Mineral wool would be destroyed one way or another very quickly. If you insulate the outside of the firepot you'd vastly increase the chances of overheating the pot, likely ruining it.

The bottom line is you simply don' t need to insulate a coal forge. You can easily get to welding temperature in a coal firepot of traditional design.

A Firepot Made of Firebricks

Above is a simple concept of a firepot of (heavy) firebricks that would set on the ground. (Pardon the distortion -- this was quick and dirty.) Some additional bricks would be needed to support the top row. An iron drain grate, such as this one:

https://www.homedepot.com/p/JONES-STEPHENS-4-in-Cast-Iron-Spigot-Fit-Fresh-Air-Inlet-Floor-Drain-J60008/202271236

would be used under the bottom as the grate, and an air pipe would be routed underground to this grate.

Hoods for Coal Forges

I am a proponent of side-draft hoods with at least an 8-foot flue. (See also, "Flues -- What size do I need?")

Some folks use an overhead hood, but I don't see any advantage to them and see a number of disadvantages. If an overhead flue is close enough to the fire to draw well, it is in the way; if not, it will likely need a motorized inducer fan to draw at all.

Some folks who use overhead flues solve the draft problem by putting sides around the forge up to the hood -- like a chemistry lab fume hood. I don't care for that design. It might be marginally more effective at venting smoke, but it limits access to the forge.

I've seen nothing better than a side draft hood and a smith who knows how to control his fire. (There should be little or no smoke from a coal fire -- definitely not enough to smoke you out of your smithy.

A Smoke Shelf in a Forge Hood

There's a body of misinformation out there about a "smoke shelf" in the forge hood. A smoke shelf is totally unnecessary -- unless you use an excessively large-diameter flue.

The smoke shelf was invented by Benjamin Johnson in the late 1700's as a remedy for chimneys that wouldn't draw -- because they were of too large a cross-sectional area. At the time, chimneys were cleaned by boys sent down into them, so had to be large enough to accommodate a small boy. Since such a large flue would never heat enough to draw well, Johnson installed smoke shelves to block off about half the flue area. This allows the hot combustion gasses to run up the front of the flue while could outside air can run down the rear flue before mixing with the hot.

Unfortunately, this feat was then given magical status in the lore of flue design and propagated into the metal forge hoods blacksmiths commonly use. Just ignore that hoopla. An 8'-10' x 8" flue pipe brought down to your forge, the bottom 10" opened out as an entrance will work just fine. (That's right. You don't even need the side-draft hood -- but the hood can take the heat and last longer than a mere flue pipe.)

Blacksmithing Techniques

Heat Colors -- and an Alternative Means of Describing Them.

Many references use colors to describe heat: black, dull red, blood red, cherry red, bright cherry, orange, yellow, white, etc. That's all well and good if you understand the terms, but is not so useful when you're a newbie and have no clue. Therefore, when teaching a newbie, I refer to heats by four terms only: black, dull, bright, and welding:

• "Black heat" is black -- even in the dark. Be careful, though, cause it's hotter than a "hot" kitchen over and can burn you badly.

• "Dull heat" is incandescent, reddish in color, but clearly not very bright.

• "Bright heat" is anything that truly is casting light, albeit red or orange light, not white.

• "Welding heat" may be seen by different people or at different times or under different ambient lighting as anything from a bright orange through yellow to white, but basically is the brightest color you can see amongst the coals in a coal forge. A workpiece that is at welding heat is camouflaged (invisible) in the coal forge until you move it so you can perceive its outline.

Removing Scale from Steel

A pretty safe way to remove scale (the black oxide that forms when steel he heated to red) or rust (the familiar red oxide)is to pickle it off. Try pickling overnight (or more) in vinegar. Or use sodium bisulfate solution ("pH Minus" or other brands for pH control of water in swimming pools). You can use diluted muriatic acid (HCl) but be careful as it can cut metal quickly.

Always pickle metal outside or in a very well ventilated area as it may generate hydrogen gas.

Scrolling

Beginners tend to think the anvil horn is a mandrel for scrolling. While it can be used that way, the horn is mainly a fuller, not a mandrel. The better way of scrolling is over the edge of the anvil.

For further information, visit the NJBA Newsletter archive at NJBlacksmiths.org and view:

Vol 1 No. 2 p. 6

Vol. 5 No.2 p.17

How a Striker Should Swing a Sledge Hammer

Assuming you're right hand is dominant:

· Right hand grips sledge handle maybe 6"-12" from hammer head.

· Left hand grips handle maybe 6" from end of hammer handle.

· Left arm held close to belly, its purpose is to take the weight of the sledge.

· Right arm and shoulder provide the swing and most of the power of the blow.

Raise the sledge to near vertical and ensure the end of the handle is off to the right of the torso, and the left arm is carrying the weight of the sledge. Rehearse your sledge swing in slow motion, from hammer head fully overhead to almost down to the anvil, to ensure the mechanics work out right (not like in video).

How to Punch a Hole in Hot Steel

Pin punches or other flat-end punches are commonly used for hot-punching steel. The circular edge should be sharp, not rounded. Be aware that they pick up heat from the workpiece, at which point they can easily bend. The smaller the diameter, the worse this is.

To properly use these, get your workpiece up to a red heat then transfer it to the anvil, locate the punch on the workpiece, and strike once to mark the punch site. Immediately cool the punch in beeswax or some similar material. Then reheat the workpiece to a bright heat and in one fluid motion place it on the anvil, place the punch at the mark and strike firmly ONE* time. (That takes 3 hands, so a striker helps.) Cool the punch immediately.

Repeat till only a small "biscuit" remains at the bottom of the hole, then leave the workpiece on the anvil till the biscuit JUST turns black**, flip the workpiece over and drive out the biscuit from the other side.

_____________________

* If you strike more than once, your punch may heat up and soften. You can get away with multiple strikes if your punch is large enough.

** If you attempt to counterpunch the biscuit while it's still red, you'll likely fail. Cooler iron is much more brittle than hot iron, as should be obvious.

How to Forge Weld

After much frustration and many failed welds, I received instruction from none other than Frank Turley. I don't recall whether I learned all the following tricks from him (probably not) but these are what I've gleaned over the years. I usually succeed in my forge welds, so long as I'm not attempting them in bright sunlight (which conceals the true colors).

• Learn how to prepare appropriate scarfs. I encourage newbies to start with one-piece welds -- faggot welds -- wherein the end of a rod is folded back on itself. If the rod is square or rectangular, the scarf need only be a "chisel" point, tapered inwards at the sides. If the rod is round, the scarf is even simpler -- a fairly abrupt round point. More complicated scarfs are needed for more complicated welds, but don't worry about that till you need them.

• (If you aren't sure whether a scarf "design" will work, mock it up by "forging" Plasticine clay. If you get "cold shuts" in the clay, you'll get them in the steel, that much worse. Example: If you start with a square bar and fold the end over 180* without scarfing the end, when you forge weld you'll get a cold shut where the end of the bar cuts into the length of the bar. Understand this and you'll understand the need for scarfs.)

• It is not sufficient for only the area to be welded to be up to a welding heat. That heat should extend at least a short distance from the area to be welded, and you should have a bright heat at least 2" on either side of that. Otherwise you'll never have time to get the piece out of the fire and to the anvil before the cooler iron sucks the heat from the weld site.

• When steel is at welding heat, it "disappears in the fire." This is almost literally true. The brightest color of the coal is approximately the correct color for steel ready to be welded. When the steel reaches this same color, there's no contrast -- so you can't see it.

• Therefore, leave a small hole through the pile of coal so you can see the workpiece, and move the workpiece around just enough that you always know where it is (lest you burn it). Some folks describe the appearance of steel at welding heat to be "liquid."

• Prepare in advance, as a tool, a sharp-pointed, straight poker, say, of 1/4" roundstock, at least 2 ft long (because your fire will be HOT). Leave the tip of this near the top of your (coal) fire to keep it hot, but be careful not to burn the tip.

• When you think your workpieces are getting hot enough to forge weld, lightly press the tip of this poker to each piece (straight-on, not side-on -- i.e. the tip, not the side of the tip). If they're at welding heat, they poker will stick (i.e., weld) to them -- but can easily be pulled off. If it won't stick, the piece isn't hot enough.

• When nearing ready to weld, make sure your anvil is clear of obstructions and your hammer is where you can grab it quickly. It is at that moment that the difference between an anvil close to the forge and one a step away makes all the difference between a successful weld and a failed one.

• It helps a lot to rehearse exactly what you will do when you pull the workpiece(s) out of the fire -- and this is essential for a "drop-tongs weld" or when working with a striker.

• "Tappity, tappity; whackity whackety," I was taught many years ago. This means that the first few blows to effect a weld should be very light. At that moment, the steel is quite soft and flexible and all you're trying to do is bring the two surfaces together and to expel the liquid flux. If you hit any harder at that point, the two surfaces may literally bounce apart.

• Once the two surfaces stick together, you may increase the force of your blows so as to complete the weld. Even then, however, be careful not to hit too hard -- the steel is still quite soft and you can end up thinning the junction too much, leaving yourself with too thin a piece. (That's why we thicken the piece by upsetting before forming a scarf.)

• Forge weld in at least 3 heats: first to flux, second to tack, third (or more) to complete the weld. Then, before you lose the last heat, shape the piece as you want until the heat is too low.

• If you have a treadle hammer and the weld is of a suitable type to employ it (like a simple faggot weld), that's the way to go. My treadle hammer has a 55-lb head and packs a wallop -- and doesn't bounce. Hence I can effect a forge weld in a single blow on it, albeit it some refinement of the forging may be necessary after that. The key is that it doesn't bounce. As I mention above, the heavy hit is not essential to effecting a weld.

• "Teeth" or steel filings are sometimes used in surface-to-surface welds. "Teeth" in this sense are chisel-cuts in one surface (usually the harder steel, as the steel would be for a wrought iron axe head) that are expected to cut into the softer steel and hold it in place during the weld. Steel filings (employed in the flux, not loose where they'd just burn up at the welding heat) are the same idea, differently executed. I don't consider these techniques to be necessary, but I'm sure others would disagree.

Hammer Marks

Back in the day, the absence of hammer marks on forged work was the sign of a competent smith. They even used files to pretty up the work. Then along came machines that did away with hammer marks completely. Now the misinformed public thinks that it isn't hand made if it lacks hammer marks.

Nonetheless, if you're trying to sell your work, you may need to meet the customers' expectations. Some folk make "texturizing hammers" or similar tooling to add texture to steel. Others just whack away with a ball pein hammer.

Using Flux in the Gas Forge

Take care. Gas forges are insulated -- unlike coal firepots. That insulation, be it mineral wool or lightweight firebrick, will be damaged or destroyed by flux. Borax will eat through hot mineral wool like hot water through cotton candy.

The simple solution is to use a sheet of stainless steel on the bottom of your gas forge. This will catch the flux and keep it off the mineral wool or firebrick. When cool, you can soak it in water to remove the melted borax. If you don't have a better source of SS sheet, get a SS cookie sheet. If your sheet is large enough, bend up the edges to give you a trough to keep splashes or runs of molten flux off the walls and floor of the forge.

A Lovely Finish Coating for Food Use

Apply a THIN layer of polyunsaturated vegetable oil to your kitchen or campfire ware and place it in a 400F oven for an hour. Or do the same over the forge at slightly higher temp -- the oil should begin to smoke, but not burn off. When applied over black steel, the result is beautiful, shiny black finish.

Miscellaneous and Off-the-Wall Notes

Forging Toy Clay

Toy clay (Plasticine) can be used in lieu of hot steel for practicing blacksmithing. It's nowhere near a perfect representation of hot steel, but it's better than nothing. (Play-Doh works too.) Each brand or type of clay is a bit different and you may have to warm yours "just so" to get it to work decently.

One thing it can readily teach you is how much or how little steel you need for the object you intend to forge. (Newbies always seem to think they need a shitload of steel to make even the smallest object.

Another is the steps you need to take to get from the bar to the final shape. (Sometimes you cain't get theah from heah.)

Some folks have used it to "practice" pattern-welded forge patterns. I can't speak to that.

Forging with Cast Iron?

Not recommended. In general, cast iron is quite brittle.

Steel might start as cast iron, but the first step, whether in bloomery, refractory furnace, Bessemer converter, or more modern techniques, is to remove much of the carbon content of the latter -- which can be up to 4% or so. That's just too much carbon for the iron to be worked.

The layering technique (in pattern-welded steel, a.k.a., "Damascus") is at least in part to equalize the carbon content through the billet. It turns out that carbon moves fairly readily through steel at forging and welding temperatures. I've read that the layers can still be visible (e.g., when the presence of nickel makes some distinguishable from others) and the carbon content be equal throughout.

Malleable Cast Iron

There is such a thing as "malleable cast iron" in which the bulk of the carbon (as iron carbide) has been spherodized -- made into little spheres in a matrix of what amounts to being high-carbon steel. That takes an annealing process. I have read that it can actually be difficult to get those little spheres to redissolve as carbon content throughout the iron. If so, it's conceivable that malleable cast iron could be worked as you suggest. A metallurgist would know better than I would. Malleable cast iron objects are often so labeled. (I doubt that cheap cast iron pans are malleable.)

A possible cheap alternative for gas forge insulation

https://www.youtube.com/watch?v=0IbWampaEcM

Such a material -- a putty -- would probably have to be renewed fairly frequently, but would be cheap to make. Among the possible ingredients are

• flour

• corn starch

• sugar

• baking soda

• borax

If anyone chooses to try this approach to insulating a gas forge, please let me know. I'd be very interested in your results.

If you're gonna work in a shop, ya gotta learn to patch clothing

Tips:

• Always save old clothing for use for patches, spare zipper pulls, buttons, etc.

• Pick up some "Stitch Witchery" or equivalent. It's like an iron-on patch without the fabric. Several different brands out there.

• Learn to use an electric steam iron.

• Learn to use a sewing machine, especially the zig-zag, which secures patch edges and does a credible job of "serging" raw edges of fabric.

• Learn to sew an overhand stitch -- the best way to secure the edges of patches you can't reach with the sewing machine.

You learned one craft, you can learn another.

Is the Knife You Want to Forge Legal?

I suggest that anybody who wants to make knifes should look up the laws in your state. For example, my state prohibits daggers -- stabbing knives sharpened on both edges. There are other regulations as well, but since I don't make knives (for lack of interest) I don't recall them.

In all probability you can make anything you like, so long as it doesn't leave your property, but carrying it, or even having it in your vehicle might prove a problem. I don't want to hear of knifemakers being arrested because they inadvertently broke a law they didn't know existed.

Mind you, that still leaves a lot of types of knives that are perfectly legal, despite being potentially as lethal as a dagger. Nobody ever said the law always makes sense.