Friday, June 25, 2010

Wrought Iron

The term “wrought iron” has come to mean different things to different people. To a blacksmith, it refers to a raw material, not a type of work. In the first half of the 19th century, much of the nation’s wrought iron was made in the mountains of Pennsylvania and in the Adirondack Mountains of New York. It was made right on the mountainside where it was mined, and was smelted in a furnace called a bloomery. The newly smelted iron was called a bloom.
Wrought iron contained a small amount of a rocky impurity called “slag” which was silica from left over from the rocky ore. The more the iron is forged the more the impurities are worked out of the iron. As it was forged out, folded into layers, and re-welded it became more refined. Iron could be refined through the stages of muck bar, merchant iron, single refined, twice refined, and triple refined. Each refinement produced a finer grain within the iron and silica.
Here is a refined bar:
One way to identify wrought iron is to cut a bar partially through and then break it. If the break looks fibrous and stringy, it is likely wrought iron. You can see that in this cut piece:

Wrought iron is very tough, malleable, and forges nicely. However, it cannot be hardened for a good cutting edge.  That requires steel--an alloy of iron and carbon. Here is a traditionally forged hammer head that has a wrought iron body and a steel face forge welded on each end:
Wrought iron was the main material used by blacksmiths until the late 19th century. The Bessemer process of making steel directly from ore was used by Carnegie Steel, and was responsible for making steel cheap. As steel became more affordable in the late 19th century it helped produce a profusion of tools and hardware made of steel. Wrought iron continued to be made through the 1940’s but it never regained prominence as the primary metal of industry.

Thursday, June 17, 2010

Link by link, chain by chain.

Traditional blacksmith’s work is particularly satisfying when the item to be made is real and needed. Such is the chain maker’s lot. Forged chain was an essential tool that was in demand. It was used with horses and oxen to pull farm wagons, logging sleighs, and stone boats. Chain was used to anchor ships in the harbor. A forged chain was even strung across the Hudson River during our Revolutionary War to keep the British from sailing up river. Chain today is largely made by automated machines. But for over 1000 years (900 to 1900AD) chain was made link by link through craft and skill.

I have been making chain for the farmers to use with the oxen. Each link starts out as a 7-inch length of 3/8th-inch round bar. It is bent to a U shape.  Next, the link is prepared for forge welding. The ends are scarfed to a wedge shape and overlapped. They are heated and fluxed with borax to prevent iron oxide from impeeding the weld.  Working on the anvil and over the horn, the link is welded to a solid link and forged to a nice even oval shape.

When the smith has turned two-thirds of his pile of U-shaped links into nice welded ovals, the chain assembly begins.  Two welded links are scooped up with an open U.  The ends of that link are welded making a 3-link chain.  Once all of the links are joined in sections of three links each, then the smith starts joining sections of 3s together with an open link to make chains of 7 links.  Then, he joins two 7s with an open link to make 15s, then those to make 31s, and finally two chains of 31 with an open link makes a chain of 63 links.  Then, he might add a nicely forged hook to each end.

If all went as planned the chain is now 63 links, two iron rings, and two iron hooks!  It should be very close to 12 feet.  That is just right to use with oxen to haul the stone boat or the harrow in the field.
Throughout history chain was needed and highly valued. But it was also utilitarian and commonplace. Therefore, the chain maker’s work was essential and difficult, but carried no great prestige. If a swordmaker produced a blade with 500 layers of forge-welded steel, they were respected for having created a masterpiece. If a chain maker produced a chain with 500 forge welds they have made a 100 foot chain. It is just a half week's work.  Tomorrow, he would begin to make another chain link by link, foot by foot!  And be careful with those welds because everyone knows chain is only as strong at it's weakest link!

Thursday, June 10, 2010

Spring Horseshoeing

Our Percheron draft horse, Zebediah (Zeb), came to the shop recently to have his hooves trimmed and shoes reset. Why is this done? The same horseshoes that protect his hooves from excess wear and damage also prevent them from wearing as they grow. Every two months he is visited by his farrier to check his hooves, trim them to proper length, and get new shoes as needed.

Dan and Zeb

The old shoes are removed. Then Zeb’s hooves are trimmed to a proper length and angle. Any problems are corrected. Then the shoes are adjusted to fit. Zeb’s shoes are hand forged, and each one is fitted to that foot. The front shoes are shaped differently from the hind shoes, and the lefts are different from the right.

Shoes may be used a second time if they aren’t too worn. Even shoes being reused are adjusted to fit the newly trimmed hoof for a perfect fit. Zeb’s shoes are hot fitted. That means that after the hoof has been trimmed and rasped smooth, the warm shoe is pressed to the horn-like hoof. A puff of blue smoke drifts away. A black line shows where the shoe has perfect contact on the hoof. Any white marks are spots the shoe isn’t in contact, and needs to be corrected to prevent the shoe from working loose and being thrown. You can see in the pictures that Zeb is relaxed, and that it doesn’t hurt him at all.
After the shoes are perfectly formed and fitted, each is nailed on and clinched. The nails are specially formed to fit well and stay in the hoof wall. It doesn’t hurt Zeb any more than getting your hair cut hurts you. The whole purpose of shoeing is to prevent the pavement and abrasive gravel from damaging and hurting his hooves.

Zeb really doesn’t mind the shoeing.  Once the shoes are well fitted and nailed in place Zeb is ready to work.  If you visit, look for Zeb at noon pulling our farm wagon.  He is an essential and popular part of The Farmers' Musuem.

Friday, June 4, 2010

A good day’s work in the Blacksmith Shop

The Fields Blacksmith Shop is both a historic building open to the public as well as a workshop producing restoration hardware for the Museum and items to sell in Todd's General Store. As a result, our work is both different from a shop in the 1840s, and from a modern ironworking shop. We produce accurate hardware and tools for restoration and upkeep of the Museum structures through use of traditional methods. We do, however, live in the modern world. Last week a little girl was visiting with her family. After looking around the blacksmith shop, she asked where I slept! She was a little disappointed to hear that I don’t live in the Museum.
Our day always starts with building fires and planning the work for the day. That can include a number of projects. We generally have a short demonstration project, a medium length repair or production job, and a long-term large project underway each day. When children arrive and want to see blacksmithing, we make nails, pot hooks, or other small quick items. Those are used internally or sold in the store. We use around 2,000 nails each year just maintaining our own buildings!
When visitors are patient we work on more complicated projects like trivets, tool-making, or historic repair hardware like hinges. Finally, when the shop is quiet, we work on the largest and most complicated projects. Currently, that includes making a large weathervane. It will have around 40 separate forged and decorative parts. I’ll post more about that project soon.  Here are some weathervane components:
At least once each week an emergency repair arises within the Museum. In the last week, we have made parts for the broom maker’s winding machine, helped the printer to cut type, and made display hardware for the Todd's General Store. We could easily get jobs like making nails to repair a door, parts for a latch, or repairing a tool for the farmers. Last week, we cleared a space in the shed for our farrier to shoe Zeb, the farm horse.

There's always something new to do at the Blacksmith Shop!
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