As we all know, there are many, many types of signs out there, made or fabricated in a multitude of ways, using a wide variety of materials. Even all-metal signs can be built a thousand different ways. But, let's take a look at one way to produce a clean looking monument sign, made mostly of metal, using simple tools and techniques of construction for this month's "Shop Talk". An "H" with two cross members is welded up, and the box for the base is made of two "picture frame" assemblies made of angle. The photos should illustrate this more clearly than this description, but the structural assembly is very basic and goes together quickly.
The sign itself is made from .040 white aluminum, bent on a brake to C-channel shape, with a 13" web and shallow 1" tall edges. The two long sides are 6' long, and the short sides are exactly 4' long. The only real hardware used in building this dimensional sign is a few rivets used to connect the corners to some 1" x 1" angle pieces also made of white aluminum formed on a brake. Except for the two long sides, formed on a friend's large sheet metal brake, all the other channel pieces were made using our shop's 4' Tennsmith brake and shear.
Once the perimeter of the sign is put together, some brackets are secured to the inside of this frame for the internal ribs or channel pieces to attach to. These six aluminum angle brackets and the internal channel members or ribs, and even the faces are attached with 3M's VHB foam tape, 3/4" wide by 1/16" thick.
As the photos show, matching holes were cut in the channel pieces through which the sign posts will extend. The holes at the top of the sign, which will never be seen since the sign is more than 8' tall, are larger and rectangular to serve as access holes for installing the hardware that will lock the sign in place against the uprights once the sign is erected. These access holes will have covers that will mount flush with the top of the sign and be totally out of sight.
HOLDING THINGS TOGETHER
Once the frame is completely assembled, it is laid flat on a perfectly level and untwisted work table. If the sign was assembled on a twisted table, once glued into shape with VHB tape, the sign would hold that distorted shape forever.
The sign faces are made from more rigid .063 white aluminum sheet, cut to exactly 4' x 6', and the sign frame must also be exactly this size and perfectly squared. VHB tape is put around the four edges and on the edges of the ribs as well. The adhesive of the tape is kept covered with its silicone paper, but long extensions are made for the rib tape, which is split at the center of the sign, and these extend past the edge of the sign.
The aluminum sign face is kept masked with its pink poly masking on the front side, but cleaned with lacquer thinner on the back side, which will contact the VHB tape. One face is set in place over the liner-covered tape, placed in perfect alignment with the frame, and temporarily secured so it won't move using masking tape along the edge in several places. Then, the release liner is pulled from the tape on the internal ribs. Having been split at the center, it is pulled back from the center out to one side, and then from the center to the other side. Then the sign face is pressed into place. Rest assured, this is a one time, forever step in the assembly.
|These pieces will provide a lip on the access openings for attaching hatch covers flush with the sign’s surface.|
Lastly, the liner is removed from the VHB tape around the perimeter of the sign, and the face is pressed firmly in place around its edges. If done correctly, it is perfectly flush with the channel edges of the sign, and will need no other hardware at all to keep it there.