Celebrating 50 Years of Truss Design, Part III

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Issue #10231 - October 2018 | Page #8
By Joe Kannapell

Part III: In-House Computing (Almost)

In 1971, for the first time, both On-Line Data and Gang-Nail, Inc. put computer software at the fingertips of truss designers. By 1973, our company responded, and so did most of our major competitors. This innovation was wrought out of near desperation on the part of CMs struggling to grab a significant share of the hottest housing market in U.S. history. This was also a time when inflation was nearing 10%, the economy was growing at a 6% rate, and unemployment was below 5%. The arrival of computer access rapidly transformed truss plant operations, both in the office and in the shop.

On-Line Data was the first to automate the generation of truss cutting lists. This leap forward was the result of the work of company founders, Dan and Camilla Hurwitz, that began in their St. Louis truss plant, Woodtech, Inc. As they started their business, the primary tool to generate cutting lists had been a thick manual, “Building Component Cutting Specifications,” by the Clary Corporation (copyrighted in 1961), which was supplied with the Clary Component Cutter. This manual contained a wealth of data, but only for common trusses, and required manual adjustments for overhangs or chord sizes. When truss configurations were not in the Clary manual, calculations were necessary. Believe it or not, the only available calculators were mechanical behemoths, like the one shown here. But no such calculator could resolve geometric functions required to calculate angles. So every truss plant supplemented the calculator with a copy of “Smoley’s New Combined Tables.” Undoubtedly Camilla, who had earned her PhD in college, realized she could overcome that tedium by writing a program to resolve the geometry for specific truss conditions. Clary Corporation, recognizing the advances made by the Hurwitzes, bought their truss plant and programs, hired them, and moved them to Texas. When the (inevitable) demise of Clary’s mechanical calculator division threatened their existence, Dan and Camilla were able to buy back their programs, and form On-Line Data.

Though computers were too expensive for most CMs, On-Line and others relied on “Timesharing,” a new technology that enabled remote users to share valuable time on a mainframe computer. In point of fact, users were never “on-line” with the mainframe; they were on a line that was a telephone line to the computer. There was no interactivity with the computer in the Seventies; truss parameters were typed in a defined sequence on a teletype machine that translated keystrokes onto a yellow paper tape. The tape was fed into a reader after a phone connection was initiated. The teletype, developed by Western Union for sending telegrams using Morse code in the 1920s, was now deployed in truss plants sending bits of computer code representing truss configurations. Though turnaround time was longer and timesharing costs were higher during prime business hours, the productivity of truss plants and their accuracy were vastly improved. Arguably, the truss industry had come of age.

On-Line’s greatest contribution to truss technology was the “line-input” method of resolving complex truss geometry, which later formed the basis of SketchPad and, still later, MiTek’s Versa-Truss. By creating short-hand notation for describing the lines which formed the perimeter of truss members, truss designers were freed of Smoley’s and laborious hand calculations. This powerful software enabled a whole new group of people to enter the field of truss design, who may not have been skilled in higher math, but who were meticulous and thorough in following program instructions.

As truss jobs became larger and more complicated and the penalty for truss cutting errors became so steep, few companies could operate without in-house computer capabilities. Yet I did sell an Easy-Set component saw to a remote truss plant in 1990 that had never used a cutting list. After we installed the saw, they continued to lay out truss chords on the floor of the plant, scribing the end cuts of webs, and cutting them with a skill saw. They then inserted the cut pieces onto the conveyor of their new saw, and adjusted the carriage and angulated the blades until they rested on the cuts. Needless to say, we quickly schooled them on generating cutting lists.

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In-House Design

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