Assembling the Truss: Engineer in Training Open Web Level Two Blog: Part III
by Jason Fitch, Engineer in Training at RedBuilt™ Since all of the chords and webs were made, and all that was left was to assemble the truss, it would be easy from here. If you thought that, you, like me, would be wrong! Karl and I started in the middle of the truss. Ed explained to us how the web layout goes and we assembled the truss components using index pins to line up the webs and other hardware like bearing clips and bridging clips. After everything was in place, Ed did a quick inspection of the layup, and we rolled the truss forward to the pinners. By this time, Mark Scarlett, the Hillsboro Plant Manager, had joined us. He told me that we had it easy because of the pneumatic pinners. “We used to drive the pins in with hammers,” he said. Well, it’s a good thing because although I’m a former framer, it’s been 5 years since I regularly swung a hammer, and I don’t think after all this time I can swing a hammer that much. Even if I could, I like my fingers too much to risk it! The pinning went fairly quickly and without much problem. The truss was then rolled outside to be checked for camber and to verify that it was within tolerance. It was spring in Northwestern Oregon, so of course it was raining. We went outside, and as we rolled the truss under a canopy to check the camber, I noticed some snickering from some of the plant associates. As we went around to the end of the truss to see what was so funny, it became very apparent, very quickly - there was a bulge in the top of the truss! The consensus was, “I think you messed up. Probably a web length.” And I thought everything was going so well…should’ve known better since nothing’s as easy as it looks! We pushed the truss forward to a place where we could inspect the problem. We found that webs 16 and 18 were switched. The reason? When I was writing the web numbers on the webs, I made the 6 look like an 8. Oops! [caption id="attachment_404" align="alignleft" width="300"] Ed Medley (left) explains to Jason how to remove a wrong web and replace it with the right one as Karl Hendrickx (middle) and Nick David watch on in the rain.[/caption] At this point, I got to learn how to disassemble and reassemble a portion of a truss. We pushed the truss out from under the canopy, and in the rain, we used pneumatic tools to drive out the pins and remove webs 16 and 18. Once removed, we switched the locations and reinstalled the pins. Now that the truss was built correctly, we brought it back under the canopy to check for the proper camber and pin-to-pin span. We found that the truss was within tolerance, and equally as important, I found a new respect for attention to detail and the work our plant associates perform so seamlessly. With a fully (and correctly) assembled truss, we moved on to the fun part…breaking the truss. We rolled the truss into the testing area and prepared it for its demise. Read about the next part of this series, The Destruction.
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