The roller gantry had two major obstacles to clear in the 1970s, both erected by its inventor, Carroll Sanford. Both were delineated in hard-to-evade U.S. Patents. The first was on the machine itself and the second was on the connector plate that it required. The simplicity of the gantry machine nearly precluded alternate designs. For this reason, the bulk of our industry bought hydraulic presses during this decade and used a longer toothed connector that worked well with them. But since we truss plate suppliers make more money on plates than machinery, we were determined to develop a plate that would work with the roller gantry.
Sanford’s connector plate designs don’t look effective [See PDF or View in Full Issue], but his patent claims surely were. Yet a few companies were able to launch roller plates (shown below [See PDF or View in Full Issue]), but without much fanfare. The rightmost candidate, by saw maker Clary Corporation, gained the most traction in the marketplace, and its symmetrical configuration pleased our engineers. However, to differentiate our plate and improve its performance, we added teeth to their circular clusters.
By chance, at this juncture in 1970, I came on the scene as a bit player, testing our enhanced version of the Clary plate. Unfortunately, the values I obtained were marginal even when we pressed the plates hydraulically but were below par when we embedded them with a 16” roller. While I continued to test other prototypes, the housing recession engulfed our industry in 1973, and we abandoned the project.
By 1975, the economy bounced back, and renewed our determination to develop a truss plate that we could supply to the gantry market. To that end, we hired a wood scientist, Dr. Larry Beineke, PhD to undertake our development. In less than a year, Larry delivered the Posi-Tooth truss plate, which worked well in both vertical presses and rollers. Soon our major competitors followed suit; Gang Nail introduced its nearly identical GNA plate and Truswal introduced theirs in 1979. Alpine had improved upon the Sanford design after acquiring it. Thus, by the end of the 1970s, all of the major plate suppliers were able to service roller gantry plants. However, we were still barred by the Sanford patent from building gantry equipment.
Entering the 1980s, the demand for trusses increased far more than the rise in housing starts – and starts doubled by 1984. More roofs and even floors were being converted from stick framing. During this runup, open web floor trusses firmly established their dominance in apartment construction, especially among Texas developers and their truss suppliers. Since a floor truss has twice as many pressing points as a roof truss, use of a roller gantry yields a much lower cycle time. In concert with the economy, truss machinery sales increased and generated the capital needed to ramp up improvements. And most consequentially, Sanford/Alpine’s roller gantry patent had expired.
But the roller gantry had been conceived 25 years earlier, when pitches were low, setups were easy, and truss runs were lengthy. Over the ensuing years, as Alpine expanded from Florida across the nation, they gradually modified the gantry tables and jigging, but retained the basic design of the Sanford gantry head. In 1980, the industry launched the BCMC Show, which greatly increased the visibility of truss equipment, and spurred competitive innovation. As the Show continued to expand through the 1980s, the race to win sales of truss equipment intensified and brought the roller gantry to the forefront.
Next Month:
Part VI: Roller Gantries Enhanced