Attendees at BCMC 2019 stood safely right next to an awesome gesticulating robot and became immersed in observing record-breaking truss building – virtually, that is, through a VR headset. Back then, Trussmatic robots hadn’t made it stateside, and hadn’t yet handled our crazy configurations and crooked lumber. But, during the last two years, in nine U.S. facilities, they’ve built tough trusses and have used Southern Pine. While they do it differently, they also capitalize upon tried and true truss technology.
Trussmatic, like others, moves its robots on a linear track, but they feed a wall and not a table, keeping the robot arms within the closest reach of the jigging, tooling, and truss parts. Trussmatic’s vertical assembly also dramatically compresses floor space requirements, especially with the recent installation of a back-to-back system. This orientation combined with air clamping produces the tightest joints without manual intervention.
Trussmatic has skillfully included familiar processes in each of the following assembly steps (for images, See PDF or View in Full Issue):
- Step 1. Set magnetic jigging onto the wall. Especially intriguing is the way jigging is offset from the finished perimeter of the truss, paying homage to one of Carol Sanford’s long neglected innovations. Sanford touted the utility of his air-actuated clamping to tighten joints on his truss tables, yet this feature was gradually eliminated from later Sanford machinery. Yet today, even with the most accurate linear saws, truss assemblers still end up hammering boards to overcome the wane, warp, bow, and twist of truss members. However, most of these irregularities are mitigated by Trussmatic’s offset chord placement and air clamping.
- Step 2. Place web members in their proper positions, which are locked into position by retractable spikes.
- Step 3. Place chords offset a fixed distance from webs.
- Step 4. Actuate air clamping, as Carol Sanford advocated, to draw chords and webs tightly together. While Trussmatic developed this technology using more uniform European lumber, it has proven to be essential with the greater tolerances of Southern Pine.
- Step 5. Fetch and press plates. Trussmatic employs a C-shaped tool to embed truss plates, retaining the advantages of manually operated C-clamp systems (see my January and February 2020 articles, Sixty Years of Machines, Part II: A Pressing Issue and Sixty Years of Machines, Part III: Table Presses). While no press can completely embed large truss plates, the Trussmatic tool can engage a “step-press” technique when required, long used with manual C-clamps, to press the nearest portion of the plate, then moving incrementally further into the joint to press a second time and repeating that motion until the entire plate is mostly embedded. Unlike Mark 8 Mono-Presses, and most other C-clamps designed with only enough reach to press 2x8 chords, the Trussmatic tool may reach beyond even 2x12 chords.
- Final steps. Eject truss and lower it to horizontal orientation, convey it through finish roller to ensure full embedment, especially in dense Southern Pine, and stack trusses vertically.
Trussmatic also overcomes the most-criticized aspect of legacy C-clamp systems – its speed. By synchronization of two C-press tools and their rapid movement from one joint to the next, an output from 500 to 1000 board feet per man hour may be achieved. This enables the Trussmatic system to handle the largest, most difficult trusses, and to stack them vertically in sequence. And Trussmatic can be fed from a variety of saws.
There are two considerations that face Trussmatic users – the assembly of very complex joints and fabrication of trusses longer than 10 feet. The former is minimized by checking designs with Trussmatic software and making appropriate adjustments prior to sending to production. The latter involves building short trusses on a separate machine, such as an Auto 10 table. Neither of these aspects have detracted from the highly successful operation of Trussmatic systems in multiple installations.
What emerges from the Trussmatic robotics is the most automated assembly of the highest quality truss. Unique among robotic systems is Trussmatic’s ability to maintain jig integrity while fully seating most, if not all, truss plates. And Trussmatic’s success is further indicated by the fact that four more systems have been purchased by U.S. component manufacturers.