For this month’s Shop Talk, we’ll look at a very simple sign project, but one that has significance for every sign shop that has limited means for welding aluminum, yet needs to make signs that are clean and professional looking and hide or minimize fasteners of any kind.
This large 4’ x 8’ architectural sign, made from aluminum tubing and aluminum laminate sign face material, was fabricated using the most basic shop tools, and required no aluminum welding and almost no welding at all. The posts are secured without visible hardware, and the finishes are professional, or in the case of the faces factory applied.
Because aluminum laminate material lays very flat and has a durable factory finish, it is a favorite of sign makers today. But, having some thickness, unlike thinner prefinished aluminum sheet (.040 or .063), it is ideal for small counter-sunk fasteners. On this job the fasteners for the faces are exposed, but are so small and flush as to be almost invisible. Two faces back to back, sandwiching the framework, create a “stressed skin construction” that holds the sign together.
The posts are aluminum square tubing, 4” x 4” in size, and the posts and their caps would get a durable powder coated finish in the end. But the actual internal frame parts would go unfinished, as the top of the sign is well above eye level, and the bottom edge below, and the ends will never be seen.
The posts were slotted on a wood cutting table saw, equipped with a fine-tooth carbide tipped blade. Studs of 3/8” diameter would secure the sign to the posts, so the groove we cut needed to be a bit over .375” wide. The slot or groove was cut slightly too long, and the posts would be trimmed to the exact length last. A tape mark on the posts and on the table saw were used to get the slot cut to approximately the right length.
To slot the posts, a saw cut was first made in the exact center of each posts, and then the rip fence was moved over approximately 3/32” at a time, on either side of the saw cut. After a few passes, when a 3/8” diameter bolt would slide easily in the grove, that part of the job was finished.
The internal framework, not welded at all but held together by the faces themselves, was made from 1.5” x 1.5” aluminum tubing with an .080 wall thickness, which is not expensive but plenty strong and rigid. These were cut on a miter box saw, which most shops would have. Four shop made fittings, two for each end, were made from a small strip of steel flat bar into which a hole was drilled near each corner. A 3/8” bolt, with its head cut off, was welded to each steel strip with the threads protruding about 1”. These fittings were screwed to the ends of the two long members, and turned toward the inside of the sign.
The vertical members of the frame were cut to loosely fit between the long members and not attached to anything but the faces. Again, no welding would be needed, the critical measurement was that the long members were exactly 96” long to fit the faces perfectly.
The aluminum laminate faces sandwiched the four frame members together and some special rivets were used to secure everything together. These very low-profile rivets are made to be counter sunk, and lay really flat when installed correctly. After a hole is drilled, it is carefully countersunk, and the installed rivets seat down into the surface flush and smooth. When painted to match the face, these countersunk rivets are truly insignificant, and at any distance virtually invisible.
Once the sign was assembled, the unpainted posts are put temporarily in place, and the exact top of the posts are marked, just short enough of the top of the sign to allow for a 3/16” thick post cap. After marking the posts, they were neatly trimmed on a metal bandsaw, but can be cut just as well using a miter box saw and a slow hand. A miter box saw with a fine-tooth blade will cut a true 90-degree cut better than any bandsaw.
The post caps would be basically glued in place with a small amount of silicone after the sign was installed. The caps were shop-made from scrap pieces of 3/16” thick aluminum bolted together with small countersunk flathead stainless steel machine screws. A small sheet metal tab was included on the inside surface of each one to provide something to hang them from for powder coating.
Before sending the posts and caps to the powder coating shop, the slots in the posts were sanded and filed smooth inside and out so the sign mounting bolts, with their nuts and washers in place, would slide through them easily. The posts were powder coated a Tiger-Drylac “Steel Rack White,” which matched the pre-finished sign faces almost perfectly.
The assembly in the field literally takes minutes, and no post mounting hardware is visible. Over the protruding studs at each end of the sign, a locknut—with a flat washer—is threaded into place. The top nut can be tightened after the fact, but the bottom nut has to be adjusted fairly snug to begin with since it cannot be reached after the sign slides in place on the posts. Soapy water is used as a lubricant to ease the job of sliding the posts onto the ends of the sign, and once the sign is in place on the pots, both top locknuts are tightened securely to permanently attach the posts.
The flush countersunk style rivets are touched up carefully in the field, one small dot at a time. Getting to both sides at the same time was easier after the sign was installed.
This type of no weld sign construction is a quick build project, but it produces a sign that has a clean appearance, is extremely strong and will last for many years. For the client, or the sign maker, what’s not to like about that?