Greetings Vern,

In the October 2022 Iron & Steel Preservation Chronicle, I wrote about the lack of knowledge of the shop riveting process and the transmission of knowledge through education. This is a subject I will continue to write about in future ISP Chronicles.

Preservation of iron and steel can be a challenge if there is no record of a historic process long forgotten. It was an exciting experience listening to a shop craftsman’s description of an unrecorded process for forge welding a forked eyebar, featured in “An Intriguing Discovery” in this newsletter.

Vern Mesler 2023

Craftsmen working in steel fabrication use standard tools or fabricate tooling, jigs, or fixtures when necessary to complete a job safely and on schedule. These shop handmade tools, jigs, or fixtures were often never recorded in a craftsmen’s journal, never patented, used once, or became an individual shop’s established tool. What tooling, hammers, jigs, or fixtures did a craftsman use to fabricate a forge-welded wrought iron eyebar? Were these forge-welded eyebars made with sledgehammers or with a power hammer? How did these craftsmen produce an eyebar with a uniform head, precise bridge pin hole locations, and an overall center-to-center hole dimension within +/- 1/32”?

In my library, I have books with engineering analyses of forge welds in eyebars but no books that document the process for forge welding historic metals. It would seem that understanding how a forge weld is made would be part of any analysis on the efficiency of a forge weld. There is a record of the process, but it is not written. The record can be read by a craftsman from a fabricated piece from another historic era.

In April of 2022, we had the pleasure of attending the Blacksmith Association of Missouri (BAM) 30th Annual Ozark Conference in Sedalia, Missouri, and to see the Murray 100# powerhammer I had arranged for donation to BAM in 2019 (Murray Powerhammer Finds a Home). I was looking forward to the conference because I had asked Bernie Tappel (an experienced blacksmith and member of BAM) if he could forge weld two pieces of wrought iron with the Murray powerhammer. Tappel and fellow blacksmiths and members of BAM Steve McCarthy and Ken Jansen accepted the challenge and produced a successful forge weld using those craftsmen skills of sight, sound, and touch (Forge Welded Wrought Iron 2022).

I also brought along a forge welded forked eyebar from Michigan’s Parshallburg Bridge with the intent of finding out how it was fabricated and forge welded. Lin Rhea, American Bladesmith Society (ABS) Mastersmith, was the first to analyze the eyebar.

Rhea’s description for the fabrication and forge welding of the forked eyebar was interesting and was met with some skepticism from other blacksmiths. Rhea’s explanation for hammering out what appeared to be two or four 13/16” by 13/16” square bars from 1-5/16” round stock would seem to be impossible. (See Nan Jackson’s “Arithmetic Note” below.)

Rhea’s account begins with craftsmen hammering 1-5/16” round stock into a rectangular bar 13/16” X 1-5/8” and then splitting it into two square bars 13/16” X 13/16”. In the illustrations below, the fabrication of the forge welded forked eyebar is sequenced as described by Rhea. (I’ve found no documentation on tooling, jigs, fixtures, or measuring methods for maintaining shape and dimensions for making large quantities of a standard size.) In the first illustration the two square bars are worked to make the required shape and to scarf the ends in preparation for forge welding. In the second and third illustrations the two bars are bent in opposite directions. Forge welding is completed in the last illustration and matches the forked eyebar from the Parshallburg Bridge. (Photo insert shows another bridge with a forked eyebar, the historic Michigan Bell Road Bridge.)

Is there a sufficient amount of material in the round stock (diameter 1-5/16 inches) to form the two square bars needed for the forked eyebar process described by Lin Rhea, without shortening the rod to make it thicker? In other words, is the area of the circular cross-section of the round stock at least as great as the combined areas of the two square rods that are created early in the process of forging the forked eyebar? If we use the area formula for a circle (area equals pi times radius squared) and the side of a square in terms of its area (side length equals the square root of the area), we discover that a circle with diameter 1-5/16 inches (radius 21/32 inch) has the same area as two squares each of side length 13/16 inch, which happens to be just what we measure on the forked eyebar. (To verify this result, compute the square root of half the area of a circle of radius 21/32.) If the forging were done in such a way that the bar was not elongated or shortened, there would be just the right amount of material for the process Vern illustrates above.

On December 28th, 2008, the Shiawassee River in Chesaning, Michigan, was swollen and ice jammed. Its swift current piled ice and debris against a historic wrought iron truss bridge and ripped it from poorly designed piers. This rare historic truss design bridge would eventually be scrapped and recycled. The historic Chesaning Bridge, known as the Parshallburg Bridge, was built by the Wrought Iron Bridge Co. of Canton, Ohio, in 1889 and moved to Chesaning, Michigan, in 1999. At the time of its destruction, I salvaged bridge members of the twisted wrought iron for educational opportunities. Today, fourteen years later, sections of the historic Parshallburg Bridge are being prepared for use in education at Lansing Community College. Instructors have been given polished and etched wrought iron from the bridge that reveals the unique characteristics of historic wrought iron to provide their students with knowledge of this material. In addition, instructors received a written description of wrought iron and the history of the Parshallburg Bridge.

For more information on the Parshallburg Bridge, visit Nathan Holth’s website (search: historicbridges Parshallburg Bridge).

An excellent example of a handmade shop tool was found at the Fraser Shipyards, Inc. (Superior, Wisconsin). While touring the shipyard we were shown a row of large steel containers filled with rusted rivets. These containers at one time were in wooden sheds that rotted away, exposing the steel rivets to the elements. On top of one container lay what I recognized to be some type of holder-on. A closer inspection later revealed a tool designed to quickly hold in place a heated rivet within a ship structure, with adjustments in length made with different size pipe at the end and the offset round stock adjustment in front of the holder-on. This craftsman-designed holder-on, specialized for riveting at Fraser Shipyards, is shown below as demonstrated by a lab tech at Lansing Community College.

A holder-on is an essential tool in the rivet process. One often seen in field riveting is the bucking bar or dolly-bar, fabricated with heavy steel round stock. Chicago Pneumatic Tool Company manufactured the Boyer Holder-On for bucking up rivets.

October 2022, ISP Chronicle

August 2022, ISP Chronicle

June 2022, ISP Chronicle

March 2022, ISP Chronicle

February 2022, ISP Chronicle

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