The photo shows a 2 x 4 truss with an ANSI/TPI 1 non-compliance issue. This is something that never should have happened! Can you spot the problem? [For photo, See PDF or View in Full Issue.]
If you shouted, “a missing connector,” then give yourself a gold star! As I was ranking non-compliance items on a loose collection of inspections last quarter, I realized just how often that missing connectors is a problem. The review had me wondering if there was a common denominator with the missing connectors. An interesting connection was that most of the offending plants horizontally stacked their trusses after finish rolling the product. None of them pre-counted their connectors as a job is brought to the table. Some of the plants had mirrors under the outfeed rollers to allow the stacker to visually see the output. So, based on this very unscientific analysis, what are the takeaways of this review?
Primary Points to Consider
- Vertically stacking trusses as they are built can help reduce missing connector issues by enabling quick inspections of the back side.
- Mirrors might not be the best way to view the back side of a manufactured item.
- Your stackers may not be aware of their important responsibilities to review finished items.
- Equipment that can enhance inspection can be an unbelievably valuable asset. An example might be cameras that capture the back side of a truss and project on a large screen available to the stackers.
- Although “connector detectors” that automatically detect missing connectors would be helpful, unfortunately they do not exist – there have been attempts at this solution, but I am not aware of any current manufacturers of this enhancement.
Additional Considerations
- Level and adjust the gantry table to eliminate low spots in your table – this may help initial plate pressing, and it should be done with an optical transit twice a year.
- Consider pre-plating connectors so the back plate is fastened to web or chord members before the lumber is flipped.
- Focus on training builders and stackers to look for missing plates along travel aisles of outfeed areas – keeping this area clean means that random plates found on the floor can be reunited with a truss, and this also helps the shop identify problem areas or workers.
- Regularly review embedment on the gantry – the top plate should be pressed almost all the way in and the bottom plate about one-half of the way (any more than this can reduce the life of the gantry).
The Bottom Line
While many of my comments here are focused on back plating, the missing connector in the photo is actually on the top face of the truss. How did this happen? Looking closely at the lumber, no penetration indicates the plate was never staked. It was never plated. In addition to watching for connectors that have fallen off, be sure to take steps to ensure your builders will be working with all of the materials they will need on the line. Pre-picking connectors will help builders realize missed connections too!
An ANSI/TPI 1 3rd Party Quality Assurance Authorized Agent covering the Southeastern United States, Glenn Traylor is an independent consultant with almost four decades of experience in the structural building components industry. Glenn serves as a trainer-evaluator-auditor covering sales, design, PM, QA, customer service, and production elements of the truss industry. He also provides project management specifically pertaining to structural building components, including on-site inspections and ANSI/TPI 1 compliance assessments. Glenn provides new plant and retrofit designs, equipment evaluations, ROI, capacity analysis, and CPM analysis.