What is Wrought Iron?

In the eighteenth and early nineteenth centuries, blacksmiths
had a very narrow range of materials to work with under the
hammer. There was wrought iron, wonderfully malleable, and
three types of high carbon steel.

Wrought iron isn’t available to smiths today. What we have
instead is a variety of mild steel alloys. These are tougher than
wrought iron, suitable to more applications in this power-tool
age. What the mild steels have lost is wrought iron’s malleability
under the hammer and its resistance to corrosion.

This is an old hardy tool that Molly uses. The maker forge
welded a piece of steel to the wrought iron body. The seam is
visible in the photograph. Early trades’ tools were often made
of wrought iron with pieces of high carbon steel forge welded
onto it for cutting or other purposes. Today, we’d tend to make
the whole tool out of high carbon steel. In the past the body of
an anvil was wrought iron with a relatively thin piece of tool steel
plate forge welded to it for the working surface. Woodworkers’
tools like chisels, axes, hammers, plane irons, and so forth
were made this way with just a small piece of tool steel for the
working surface or cutting edge.

Smiths 200 years ago had three types of tool steel available.
Blister steel, the least expensive, was made by placing large
bars of wrought iron surrounded by leather scraps in huge kilns
where they were heated to high temperatures. The bars were
crudely case hardened and had a blistered appearance but still
retained a wrought iron core. Shear steel was made by reforging
the blister steel bars into a more homogenous product. Cast
steel was the most expensive steel of its time. It was made by
cutting bars of shear steel into small pieces and melting them in
a crucible. This was a truly homogenous material with wonderful
edge-holding properties for tradespersons’ tools. Often quality
tools of the period are marked “Cast Steel.” Here are a couple of
nineteenth century center bits for woodworkers. One is marked
and still has its temper color.

High carbon steels are much more varied today and have
a range of properties unknown to earlier smiths. For tool
making we use W1 or O1 tool steels – water or oil hardening.
These steels we have to anneal (or normalize) after forging
to return the steel to a soft state. This relaxes the tensions in
the steel caused by forging and prevents breaking when it is
hardened. We harden the steel tool in the fire by heating it to
the temperature at which steel loses its magnetic properties.
Then the tool is plunged into its proper quench – brine for W1,
oil for O1. The tool in this state is too hard and we temper it by
reheating it to a much lower temperature, either in the fire or in
the kitchen oven. About 450 degrees is the proper temperature
to temper a woodworking chisel. For a tool like a cold chisel
used to cut steel, the tool is heated to a higher temperature, one
at which the polished metal turns blue, about 550 degrees.

Wrought iron, unlike modern steels, has a grain, much like
wood. This large forged nut shows the grain. In forging wrought
iron, operations would have to be done in consideration of this.
Holes punched near the end of a bar would be liable to break
out. If the bar is spread first, forming a cusp, a hole punched
on the cusp would be less likely to exceed its boundaries.
Many decorative elements in traditional ironwork also serve a
functional purpose.

Because of the weakness of wrought iron and its easy
workability, a smith formed this washer by wrapping a piece of
iron in a circle and forge welding the ends. The overlap is clearly
visible. Ram’s horn nuts are useful, beautiful, and necessary
adaptations for wrought iron’s weakness.

As blacksmiths today we are having to deal with materials
changing. Mild steel, low carbon and low alloy, is difficult to find.
Instead, steel dealers in our area have products like A36 which
are versatile but tough to hand forge and which have a tendency
to form stress cracks when shaped hot. This means that a
sizeable portion of our raw stock has to be purchased from out-
of-state suppliers.

Even though our craft is an ancient one, it is not static, but
continues to evolve in accord with the world’s changing
circumstances.

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Using a Power Hammer

While most of the forge work in the shop is done by hand using a hammer and anvil, we do at times use a power hammer. Ours is used to rough out forgings, the work done in traditional shops by the apprentice, where brute force is more important than precise blows.

Image of Diderot Hammer
Diderot Hammer

Power hammers aren’t new; hammers powered by a water wheel were used in the eighteenth century and earlier. This is part of a plate from Denis Diderot’s Encyclopedie. The hammer is raised by a cog on a shaft and drops when the cog rotates away. The smith has no control of the hammer or the force of the blow.

In the nineteenth century different types and styles of hammers were invented ranging from treadle foot-powered to hammers driven by overhead line shafts. In the twentieth century hammers powered by air compressors were developed. Ours is like that. A smith with this type of hammer has precise control of the number and power of blows according to how they press on a foot control.

In this video Molly is using the power hammer to rough out forgings for the tails of latch thumbers. In an earlier post we described the shaping of completed thumber forgings.

Blacksmith’s Riveting, Brazing and Welding, part 2

In our previous post we talked about how we use mechanical joints, brazing and electrical welding to fasten metal parts together for tools and jigs in the shop. In the work we do for Horton, we use only riveted fastening: we head pins for hinges much like we’d head a rivet, and in making Suffolk latches we rivet the thumber into its slot.

While riveting is perhaps the most common type of fastening in period hardware, other types of connection were also used. We’ll be looking at a lever latch with lock, much like the one mentioned in our post on books. It’s much like the one illustrated in the Sonn and Streeter examples in that post.

This is the back of a German-style lever latch that also included a simple lock. The back plate to this latch is held in place with four nuts.

Each nut has filed decoration, even though this part of the latch would not be seen. The nuts and threaded posts are each individually sized. No nut will fit all the posts.

On the other side of the back plate a spring that holds the bar in place has been riveted.

This is the latch and lock with the back plate removed. There are only a couple of moving parts: the lever and its spring, the tumbler which holds the bar in place (the tumbler spring has broken), and the bar (note the filed decoration at the end, again this was hidden from view). The broken spring for the tumbler would be easy to replace; it is held by a rivet. Studs for the latch spring and tumbler were riveted to the front of the case, as were the two guides for the bar.

The latch handle, as you can see in the above photo, consists of a forging with a handle at one end and, after a ninety-degree bend, a bar that rises in and out of a catch in the doorjamb. The handle’s pivot (where the pencil rests) is a round piece with a square hole (to hold the handle for the other side of the door). The pivot rides in holes cut into the front and back plates of the latch. This pivot is brazed to the handle, in this case using copper instead of brass.

Brazed joints are also found in tools. The vise shown in the post about artifacts has a bit of brazing. In this case, rather than try to tap a thread for the vise screw box (or nut), what they did was wrap a piece of square wire around the vise screw and insert it in the box or nut. The vise screw was carefully removed leaving the wire in place. Brass filings were sprinkled inside and the whole was heated in the fire to braze the wire to the box.

Blacksmith’s Riveting, Brazing and Welding, part 1

There is a great book by Jeannette Lasansky titled “To Draw, Upset and Weld: The Work of the Pennsylania Rural Blacksmith, 1742-1935” that was published 30 years ago.  We’re taking a bit from the title in the next two posts in order to begin to describe how blacksmiths fasten two pieces of metal together.

In our shop we use mechanical connections like nuts and bolts, riveting (such as the thumber riveted into the Suffolk latch), brazing, and welding. We’ve not had a need to forge weld for years in what we make. If we need to weld a part in a tool or jig, we use a MIG welder.

At the top is a Lancashire pattern die plate from the early nineteenth century. Each hole in the plate cuts threads for bolt-like fasteners. We use modern die holders with interchangeable dies for each size thread, like the half-inch dies in the center. At the bottom is a modern tap for cutting threads in a hole for nut-like fasteners. The die plate at one time also had its taps.

This is the back of the spring latch that was shown in a previous post along with a knob. The parts of the spring latch were attached to the back plate by riveting — peening, lightly hammering, the metal protruding from the hole until it no longer fits through the hole and forms a secure fastening. The lever itself is held to the back plate by peening over the edges of the boss; where the pencil is pointing. The brass knob was made of three pieces: thin front and back ovals soldered together and soldered to a turned brass shaft. The knob is held to the long iron shaft by a pin.

An important tool in our shop is the blacksmith helper — a jig holding moveable dies, one of which is struck by a hammer.  We made this helper using nuts and bolts to hold the vertical parts together. These were then brazed to the base in the fire. Brazing is done by heating the iron or steel hot enough so that brass will melt when it comes in contact. Brazing makes a strong joint, much stronger than soldering, almost as strong as welding. This blacksmith helper has been in constant use for over 15 years. We’ll do a post soon on how the blacksmith helper works and the dies we use.

Forge welding was a frequently used way to fasten two pieces of iron or steel together. Forge welding is done by heating the pieces at the same time in the fire to just below melting temperature — about 2,000 degrees Fahrenheit. The pieces are taken from the fire and, on the anvil, hammer forged lightly to join them. Low carbon wrought iron welded easily without burning, unlike higher carbon steels today. This is the bottom of the large pintle shown in a previous post. The pintle and the wrapped joint are easily visible after the weld.

In the eighteenth century and on into the nineteenth, forge welding was used to attach pieces of high carbon steel to low carbon supports. This had several advantages — high carbon steel was very expensive and the lower carbon support was cheap and provided shock resistance. Plane irons and chisels, for instance, would have a small piece of high carbon steel as the cutting edge while the bulk of the iron or chisel was wrought iron. It’s sometimes possible to see in old tools the line where the two metals are welded. The high carbon steel is also more likely to become pitted with rust.

As an aside, steel around 1800 came in three grades: blister, shear, and cast. Blister steel was the cheapest and was produced as bars with a high carbon blistered outside and soft, wrought iron cores. Shear steel was used for agricultural tools and was refined blister steel. Cast steel was made by melting shear steel chunks in a crucible, making the steel uniform. Tools made using cast steel were not cast in molds as some would think. They were forged using the high quality crucible steel.

The Blacksmith’s Hands – Tongs

We’re right handed so we hold the hammer in that hand. Even though the tongs are held by the left hand, that doesn’t mean that dexterity isn’t needed. During a forging tongs are raised and lowered, shifted right or left, turned slightly or continuously. Like an athlete or a dancer, a blacksmith must hold many things in awareness at the same time. Tongs hold the hot stock and what they do is just as important as what the hammer does.

 

Forging is impossible to do well if the stock isn’t held well by the tongs chosen. Depending on the size and type of stock or how the tongs are used, a number of different tongs can be used for a specific forging.

 

 

For forging and shaping a thumber we use 4 tongs, and another pair is used to manipulate the stock in the fire. From left to right are fire tongs for removing pieces from the fire, a pair of v-tongs to hold the round stock, a pair of ½ inch flat tongs for holding the tail of the thumber during forging of the thumb press, and two tongs for holding and shaping the thumber around a jig.

 

 

The stock for thumbers for HF14 Suffolk Latches is 3/8 inches round, 3 ¼ inches long. We use the fire tongs (to the right in this photo) to manipulate this small piece of metal in the fire. The stock is being drawn out of the fire and will be handed off to the waiting v-tongs held in the left hand.

 

 

The v-tongs hold round or square stock extremely well. The end that will become the thumb press is held while the tail of the thumber is forged.

 

 

The ½ inch flat tongs are used to hold the thumber tail while the thumb press is forged. Tongs for holding flats have a distinctive shape. One jaw has a u-shaped end the width of the flat (in this case ½ inch) and the other jaw has a “pusher” to hold the stock in the “U”.

 

 

Thumbers, after forging, are shaped on a simple jig. The tongs to the right hold the thumber to the jig and the tongs on the left (a pair of ¾ inch flat tongs) is used to bend the tail to the shape of the jig. The parts of the jaw of the shaping tongs that are used are the pusher and the base of the other jaw, behind the “U”.

 

 

 

Tongs can be adapted by reshaping the jaws so they can be used for particular tasks. We filed a single groove near the ends of the v-tongs so we can hold grips, like this HF20.

A quick forging video

When Molly and I are forging hardware our time at the forge has two components – actual forging and tending the fire while the metal becomes hot enough to forge.

 

We shot a quick video of a simple forging so viewers can get an idea of what happens in that all too quick time between pulling a forging out of the fire, taking it to the anvil and forging it while it is still hot.

 

This forging is of one of the ends of an HF20 grip. The stock is 3/16 inch round, the smallest stock we forge. The metal cools quickly while we forge it – 15 seconds is all we have to do the work needed. Thicker stock holds heat longer.

 

Preparation for the forging was grinding the corners off of the ends of the 6 inch round bar so there weren’t any sharp corners.

 

When you watch the video, pay attention to how the hammer tilts slightly as the blows are made to create the round form. The blows are quickly made with the eye directing the hand based on what is seen and based on experience.

 

The stock was heated to a yellow heat and you see the part on the anvil quickly change color as it cools.

 

We often have the radio on while working, listening to West Virginia Public Radio, and you’ll hear a little classical music in the background.

Making a Suffolk Latch — The Thumber’s Slot

In the eighteenth century there were two main types of hand forged latches with grips — Suffolk and Norfolk. The Norfolk has a grip attached to a flat plate. The Suffolk latch has an upper and lower decorative cusp with an integral grip in between. We make two styles of Suffolk latches for Horton. One style has the slot for the thumber cut into the upper cusp and the other style has the slot for the thumber cut into the upper portion of the grip. The first style is a larger latch used for exterior doors and the second style is a smaller latch used for interior doors.

Cutting the slot for interior door latches is an interesting bit of hot work and requires the use of a bolster block, a special chisel and a drift.

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All the work is done on the anvil as shown here. This photo shows, on the left, the bolster block over the anvil’s hardy hole. The chisel is in position to be driven with a hammer through the hot forging. To the right is a scrap piece of steel to protect the anvil when the slot is cut entirely through.

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Cutting the slot takes several heats. We mark out the location of the slot with a cold chisel cut on both sides of the stock for the latch. This gives something to help guide the hot chisel. We heat the metal to a dull red color and use the hot chisel to deepen the cold chisel mark. When the metal is extremely hot, it is hard to see these marks so they must be located solely by feel.

In the photo above the chisel has cut entirely through the stock from both sides after a second heat.

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At another high heat the chisel is used to open the slot over the bolster. The bolster has a slot cut into it slightly larger than the one that is to be made. It supports the stock to prevent deformation while tools are being pounded through the slot.

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This photo shows the latch’s spread slot. The slot is slightly lopsided which will be fixed during drifting the slot in the next two heats.

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The drift is a piece of mild steel that tapers at both ends but is the exact size of the final slot in the middle. This allows the drift to be driven into the hot forging without getting stuck.

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The drift is driven into the forging to create the final size for the slot. Its other use is to allow the metal around the slot to be forged without collapsing the slot. It’s at this point that the slot will take its final form.

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The finished slot with the drift held to the side. After the latch forging is finished and it has been bent while hot to its final shape, the slot and thumber are drilled for a pin. Then the thumber is riveted into the latch. Those are some of the final steps in making a latch. Between cutting the slot of a Suffolk latch and putting the finish on it, there is much work to do.

New stuff!

Press release:

New: hammered iron knobs

Never content to rest on our laurels-Horton Brasses has more new products! In response to customer requests, we now offer larger, hammered iron knobs. In case you are keeping track-we have now introduced 35 new products since the summer of 2008-!!!-while others are sleeping we are finding new products. This knob is made in England-it has a beautiful hand done wax finish. It matches our hand forged iron hardware perfectly. This knob is, ahem, larger. The biggest size measures 1-1/2” in diameter, the small one is 1-3/16”. We have heard from time to time that our proportions were a little “traditional”. Larger makes a lot of sense considering the scale of hand forged iron in general. Customer input drives us, thanks to all for giving us feedback. In stock at all times; no minimum order; quantity discounts available. Check out the website: BK-8 and BK-10

hand forged iron hammered knobs

Interesting things we can make

There is a first time for everything. We have done custom hand forged iron work for many years now, and in that time we have made a lot of unique items. Most of the time we make strap hinges, latch sets, cane bolts, etc, to fit any number of special applications. From 10 feet tall barn doors to hatchway doors and everything in between. But this is new. We made this very nice box stand for a customer in New Jersey. The stand fits and antique wooden box that they wanted off the floor. The piece is 18-1/2″ square and sits 6″ off the ground. We are quite pleased with the result, and more importantly, the customer is too.
box stand
top view of box stand
close up of corner box stand
close up of legs for box stand

Now the other bits: I am a little sheepish to say, but this morning I got an e-mail, one of the feet came off in shipping. There must have been a void in the weld where it was attached. Suffice to say, it shouldn’t have come off and we will of course fix it immediately. Sometimes welding can be tricky. Second, if you find this interesting, it took 4-1/2 hours to produce and we charge $75.00 per hour for time and materials.