The name “Bill McAlpine” has such resonance in the component industry that when ITW acquired the company and removed his name, they soon found value in returning to the Alpine moniker. There are many reasons McAlpine earned that singular honor, but one of the least recognized is that, 60 years ago, he designed the basic truss plate we use today. I myself just found the proof, buried in a tiny detail on a Sanford patent, and it is worth understanding how McAlpine arrived at that design as well as why it took many years for his main competitors to copy it.
McAlpine was born at the start of the Depression. He attended middle school during World War II and high school during the period of post-war exuberance. He began Notre Dame’s civil engineering program in the year that the Fighting Irish won the national championship, and they went on to win another during his third year. After graduation, McAlpine worked several years at an engineering firm, gaining his PE license, and then answering Sanford’s ad for an “engineer to design connector plates.”
Just prior to McAlpine’s arrival, Carol Sanford was driven by his competition to develop a plate that didn’t require nailing. As he had done with his Grip-Plate, Sanford developed it empirically, relying on what he observed in the marketplace and, perhaps, on recommendations from others. The resulting plate was basically an incremental improvement over Ronel’s design. [For all images, See PDF or View in Full Issue.]
Upon McAlpine’s arrival, his first mission was to try to satisfy the increasingly broad range of special design requests, as Sanford expanded his customer base across the country (for more on that, see “Home Building Technology, Part VIII: The Engineering Advantage”). But McAlpine was also given the task of replicating the Grip-Plate’s oversized design manual to account for the vastly different design properties of Sanford’s 1960 plate.
Within a few years, competitors had developed plates with far higher design properties, threatening to dampen Sanford’s explosive expansion. Since Carol Sanford and his head salesman, Charlie Harnden, were busy setting up new accounts and putting out fires at existing accounts, McAlpine was left on his own to take up the task he was hired to do: develop a plate that beat the competition.
All McAlpine had to work with was his professional engineering expertise, as the recently published TPI-60 Code specified only the following, “…plate value per tooth… shall be either the adjusted value at 0.015” slip, divided by 1.33; or the adjusted ultimate value at failure, divided by 2.5.” There were no references to shear and tensile stresses, plate orientation, or the method of embedment. Yet, McAlpine considered all of the above, a decade before the TPI Code did, and he added a game-changing feature.
McAlpine doubled the density of teeth compared with Sanford’s 1960 and Hydro-Air’s 1963 plates, and he maintained the 20-gauge thickness, resulting in 25% less steel content than either the Gang Nail or the Hydro-Air 18-gauge plates. But, most consequentially, in a small corner on page three of his five-page patent, McAlpine included an alternate detail in which two teeth are punched together in a very specific way from the same slot in the plate, providing the ideal tooth shape for penetration of the wood, and maximizing withdrawal resistance. Not until he completed this development work and submitted the patent application did he depart Sanford, with Charlie Harnden, to start Alpine Engineered Products. Carol Sanford revealed later that he had planned to sell his business in 1965 to his key executives, but couldn’t come to agreement with them, so they left to form other plate and machinery companies.
In early 1966, at his new namesake enterprise, McAlpine created a simplified version of his Sanford double-tooth design, without sacrificing its advantages, resulting in the plate upon which his new company was built. McAlpine chose not to seek patent protection, perhaps because of the financial burdens on a start-up company and perhaps because of the intellectual property overlap with his time at Sanford’s company. Yet, Alpine’s main competitors were slow to copy McAlpine’s design, clinging to the belief that vertical press application was superior to roller embedment, even though the TPI-approved design values were identical for either method of embedment.
By the 1970s, all of Alpine’s competitors were compelled to develop roller plates, lest they be locked out of the 250 plants that had installed Sanford Roll-A-Master systems, and the hundreds of plants with single-pass roller systems. All copied McAlpine’s double-tooth design, although some staggered the teeth.
Fittingly, Carol Sanford, inventor of the first successful truss plate, had been the man who hired the inventor of its long-standing replacement, Bill McAlpine. Evidence that Sanford endorsed McAlpine’s professionalism in carrying on his legacy is the fact that Sanford gradually ceded much of his substantial plate business to his former employee and competitor, eventually selling him his highly successful and patent-protected Roll-A-Master system too. The fact that this double-tooth design dominates today’s plate offerings is further evidence of Bill McAlpine’s long-lasting impact on the component industry