In this post I will look at a type of folding ruler commonly known as zig-zag rulers, and an interlocking or slide ruler. Zig-zag rulers are folding rulers made up of a number of short pieces with locking hinges connecting the pieces. When fully opened, a zig-zag ruler is often six or eight feet long, and is stiff enough to be held in one hand while being used to measure. These are the tools that I have always thought of as "carpenter's folding rules." I bought one when I started my (one and only) summer construction job in 1962, and I have one in my garage today.
The first zig-zag folding ruler from the Tison Tool Barn collection is this Lufkin Red End rule with a slide extension. The rule is 96 inches long when fully extended. The model number on this tool is badly smeared and unreadable, but a Lufkin Wood Rule Red End with Slide Rule Extension, Model No. X48, is still on the market.
Lufkin Red End ruler with slide extension. Photo by Donald Albury.
Lufkin Red End folding ruler, partially unfolded, with slide partially extended. Photo by Donald Albury.
The next folding rule is this Lufkin Model 1206 aluminum rule with brass hinges. Offerings for sale of examples of this rule on the Internet attribute it to the period from the 1920s through the 1950s. This ruler is 7 inches long folded, and 72 inches long fully extended.
Lufkin Model No. 1206 aluminum zig-zag rule. Photo by Donald Albury.
Lufkin Model No. 1206 ruler partially unfolded. Photo by Donald Albury.
Side view of Lufkin Model No. 1206 showing accumulation of bends in the aluminum sections. Photo by Donald Albury.
The third zig-zag ruler in the Tison Tool Barn is this 24-inch long steel ruler. The only marking on it is the legend "MADE IN GERMANY." It has a leatherette case.
Partially unfolded teel zig-zag ruler. Photo by Donald Albury.
Folded steel zig-zag ruler with case. Photo by Donald Albury.
The final ruler from the Tison Tool Barn covered in this post is not really a folding ruler, but it is closely related, and is used like a zig-zag ruler. It is an Interlox Master Slide Rule, Model No. 106. Instead of legs swinging on hinges, each segment slides over the next segment, with clips on the edges keeping the segments rigidly in line. (The hinges on zig-zag rulers may loosen with use, allowing unwanted bends in an extended ruler.) It was advertised as ideal for measuring inside dimensions. This example of the Interlox ruler is 72 inches long fully extended. Rulers could be ordered from the manufacturer in one-foot increments of length. This ruler was advertised in a 1915 edition of Popular Mechanics magazine, and remained in production at least until World War II.
Interlox Master Slide Rule, exterior measurement side. Photo by Donald Albury.
Interlox Master Slide Rule, exterior measurement side. Photo by Donald Albury.
Partially extended slide rule, side view. Photo by Donald Albury.
Partially extended slide rule, top view. Photo by Donald Albury.
There are a number of plain old rulers and yardsticks in the Tison Tool Barn, but I'll get around to them some other time.
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