Having travelled across Scotland by train and bus, Nan decided to schedule a driver to take us from Inverness to Connel in order to visit some bridges along the Caledonian Canal. A bridge Nan included on our Scotland itinerary was the Bridge of Oich, a bridge I discovered appeared to be hand crafted with no parts machine produced. My focus was on the eye-bars and in particular (and a surprise) the forked eye-bars in the center of the bridge. Each one is slightly different, which would indicate all were hand crafted.
Forked eye-bars are of special interest to me because they represent one of many issues in the lack of any industrial documentation of historic shop practices. What jigs, fixtures, and tools were used in the shop fabrication of these forge welded eye bars? I have found none. I learned from a blacksmith about a possible method, where a section of round stock is hammered out to a rectangle to get two equal square bars, then bent back and forge welded.
On the Bridge of Oich, Nan measured the round stock with her diameter tape and calculated the dimension of the square bar that would result in two square cross-sections equal in area to the round stock. Her calculation matched the dimensions of the forked eye-bars on the Bridge of Oich. In the accompanying Sketchup drawings the forge welding technique is illustrated.
What would it take to replicate this handcrafted historic bridge? Skilled crafts men and women, quality pig iron, a puddling furnace for producing a batch of wrought iron, a large blacksmith forge, anvils, hammers. A wood pattern maker for the cast iron connections and a foundry to make the castings. I think it’s possible.
