Celebrating 50 Years of Truss Design, Part V

Back to Library

Issue #10233 - December 2018 | Page #8
By Joe Kannapell

Part V: A Prequel to Hands-On Design

When Lou Lewis showed our engineers his $395 HP35 calculator in 1973, they barely blinked, but several in the truss industry did recognize its value. Perhaps we were too focused on our mainframe computer, and too invested in the programs that we had written. Others, however, saw its potential to expedite cutting lists. Little did they know that Hewlett Packard was then laying the foundation for the Silicon Valley, and its innovations would have an untold impact on the truss business, and the rest of the world.

The HP35’s biggest plus was its built-in trig functions, which were used repeatedly to calculate cutting lengths and angles. Previously, truss designers spent hours poring through the tables of Smoley’s handbook. At $395, the HP35 cost less than a designer’s weekly salary and quickly paid for itself.

A few insightful individuals dug deeper into the HP35’s key differentiating feature, its memory registers, and realized their use in storing and applying routine calculations. When its successor model, the HP65, was introduced in 1974, HP called it “a personal computer” and it indeed was fully programmable. What made the HP65 ideal for truss calculations was its magnetic card reader/writer shown here, which allowed an unlimited number of programs to be accessed to calculate cutting lists, for example.

Hewlett Packard kept innovating, and so did its truss design adherents. When the HP97 with its integral printer arrived in 1977, it was perfectly adapted to the task of producing cutting lists. This capability attracted many forward-thinking truss designers, and particularly one leading truss engineer, Antonio Arce, who led engineering at Truswal. Tony developed, and Truswal was the first to market, a series of HP97 magnetic cards for cutting most common truss profiles, and even a bonus card to cut special configurations. We, like most suppliers, were quick to follow suit with a similar product. Ours was named CalCut and operated on the Texas Instruments’ comparable model, the TI-59, which we sold “like hotcakes” at the 1980 BCMC Show in Louisville.

Since this first application of “hands-on design” produced only cutting lists and not truss designs, how did CMs address engineering? Over a hundred ran their designs on our programs via Timesharing, but many more had to subsist on the standard sealed drawings we supplied, or phone in requests for the designs not covered. Though we produced thousands of binders of designs, we could never keep up with all the codes, loadings, and lumber grades requested. Fortunately help was on the way.

Hewlett Packard announced the HP 9845 in 1977, the perfect vehicle for “hands-on” engineering and cutting. Shortly thereafter, Tony Arce left Truswal and began developing his own truss software. About the same time, Robert Brooker began marketing truss software, based on his earlier work for Carroll Sanford, inventor of the truss plate. For about $15,000, the HP 9845 incorporated a large graphics-capable monitor, a letter-sized printer, and removable floppy disk drives: a self-contained, soon-to-be desktop workhorse to supply the unrelenting demand for both truss calcs and cutting.

Next Month:

Desktop Engineering Rocks Our World

You're reading an article from the December 2018 issue.

External links

Search By Keyword

Book icon Issuu Bookshelf