New inventions may fade away, but most provide valuable lessons, like the concrete truss machine. Not many of these were built, but they seemed to Cal Jureit to be the logical match for his new truss plate, and they set the course for all his future machines.
Jureit had to have been exasperated when he realized his great invention of the truss plate took dozens of tons of pressure to put to use. Each tooth was much thicker than a nail, each joint had many teeth, and each truss had many joints. Only a hydraulic press was suited to the task, as Bill Black, Sr. had recently demonstrated. But such a press was heavy, difficult to move among joints, and often had a hard time seating Jureit’s plates. Carol Sanford had introduced a more expensive, but faster, machine with multiple beam presses that spanned across the truss, but it required a finish roller to complete the job. Both machines were slow setting up and pressing trusses, especially on difficult designs. So Jureit devised a design that would shorten pressing time dramatically while being cost-competitive with Sanford’s approach. [For all images, See PDF or View in Full Issue.]
Jureit’s concept was a “super press” that could seat all plates simultaneously for the hypothetical 99% of all trusses. He figured that this required a massive hammer-like device, wielding 100 tons of force. If such a beast were designed from steel at $0.12 per lb in 1960, the cost would be $24,000 ($250,000 today), but with concrete at $14.00 per cubic yard, the cost would only be about $4,000, including reinforcing steel. Thus, in late 1960, was born the first and only concrete press.
Jureit proposed that Gang-Nail fabricate and ship a hollow, reinforced steel shell that CMs would fill with concrete onsite, since a gargantuan 100-ton machine couldn’t even be moved onto the streets of his plant in Hialeah, Florida, much less across America. Once installed, this machine would be able to press with a single stroke, trusses up to 9 feet tall and 40 feet long, at about a pitch of 5/12. “The few trusses longer than 40 feet can be put through lengthwise,” Jureit stated at the time.
Controlling this massive structure to ensure parallelism during the pressing cycle required a robust mechanism. This included four heavy duty guideposts to keep the top platten horizontal during pressing, and four tension bars to keep each end of the press descending simultaneously. Both of these features were carried over to later press designs, although a single tension bar at the top of the machine would replace those located at the bottom of the concrete press.
In the early 1960s, Jureit commissioned seven of these presses to be fabricated, but little is known about their performance, or if many more were built. But, by 1969, Jureit acknowledged “this press… (is) not particularly adapted… for elongated trusses,” and he introduced the first of many traveling beam presses with kick-legged tables.
This press would be little more than a prototype machine, with very limited production, inheriting mechanisms from the concrete press, but with a moveable beam press. Although it would require multiple pressing cycles compared with the concrete press, Jureit mitigated the additional time by enabling it to function in a totally automatic and unattended mode. That way, as Dick Rotto amply demonstrated, the build crew could assemble a second truss on the other end of the table while the first truss was being completed. This was a winning feature that gave Trussway and others the fastest and most versatile machine on the market at the time.
Shortly after Gang-Nail announced their first beam press, Jureit hired a remarkable engineer, Adolpo Castillo, who transformed this basic design into the Mark IV, an incredibly durable workhorse, and its succeeding line of Gang-Nail machines. Although the roller plate changed the machinery paradigm, Adolpho’s design survives, and in a configuration reminiscent of the concrete press, now called the Ultra-Press. Like its long-forgotten predecessor, the Ultra-Press seats all joints simultaneously, but with a much reduced coverage that is ideal for modular home trusses. And note the similarity of the “shuttle” design, allowing a truss to be set up on one side of the table while another is being pressed. Of course it is built of steel, yet transportable by truck, with a maximum weight of 47,000 lbs.
The concrete press had a rather ignominious departure from the truss business. Because it was too heavy to haul away, and too tough to cut up, the best method of disposal was to bury it in the back of the truss yard, normally with little recrimination! Yet, during its limited life-span, it gave rise to some top-notch offspring. If you have doubts, ask Gus Pearson at Builders FirstSource who elected to remove a late model beam press and to re-install his 35 year old Mark IV, which he continues to use very effectively today.