The table is where wooden truss
es are assembled. A table is usually about three feet high
, 50 to 70 feet long
, and a good
20 to 30 feet wide
. The table will always be made of wood
. This allows the securing of lumber
(i.e. top and bottom chord
s) to the table with 12 penny nail
s. There is a long metal beam
affixed to the table with strong bolt
s. This is the "camber bar
It is often necessary to have at least one worker on the table. If the truss is very long, or very tall, it can be impossible to construct entirely from the ground, and hopping up and down from the table can become tiring and very tedious.
There will be another table, its length parallel to the other, with a walkway of about three feet in between tables. This table is used for backplating the truss. When the front side of the truss is entirely assembled, the truss is flipped by the workers onto the other table. The backplating table will usually have cyllindrical metal rollers on it, allowing a worker to easily push the completed truss across the table to the press, where the plates are securely fastened.
In the most extreme cases (biggest trusses), I've seen three men on the ground and three men on the table, and still not be able to flip the truss. In cases like these, we would take a seventh person, tie a rope to the peak of the truss, throw the rope over the rafters in the roof, and across to the other table, where the seventh would pull on it to raise the peak and help flip the truss.
The table should be swept clean after every set of trusses is built. It is important to make sure that there are no pieces of wood near the camber bar, as this can make it difficult to properly center the truss. Also, it is common for workers to drop truss nails onto the table. These should be picked up always. A nail on the table can be a saftey hazard. It's also wasteful to leave nails lying around.
If workers are building several of the same truss, the additional chords are kept on the table so that the table man can access them easily when constructing the frame of the truss. Webs and kingposts are kept under the table and are handed up to the table man after the frame has been built.
After a long time of usage, tables will become flaky. Splinters of wood will come loose from the table, it will be full of holes from constant nailing, and the wood in the table will deteriorate due to weather. Therefore, it is important to repair or replace the plywood on the surface of the table around once a year. A newly repaired table is much easier to work on than an old table, and the trusses come out better too.