After considering some options, and doing some testing, I decided upon my type of framing for wooden signs. First, the wood I chose was pine that measures .5” thick, .75” wide, and in this case, 8’ in length. The style of frame is called a box frame which does not require mitering or angle cuts. The top will span the length of the sign width plus the width of two sides, and sides will be the length 5.5” of the sign sides minus the thickness of both pieces. So an 18” wide sign, with 5.5” width, will have two pieces measuring 4.5” and two pieces measuring 19”.
From looking at lots of videos, it seems everyone uses a pneumatic nail gun to assemble their frames. However, I neither have space nor the inclination to have such a powerful and expensive tool in my possession. Therefore, I needed to come up with a different solution. After lots of testing, I determined that gluing will work well as long as: the frame is properly supported, and the glue is allowed to set while being clamped in place. Speaking of clamps, I purchased what is called “90 degrees, 200lb. corner clamps with 3” jaw opening” (by Dewalt) from Home Depot. These types of clamps sometimes come in sets of 4, but in this case, I purchased 4 separate clamps due to the solid metal construction I desired (lifetime warranty).
Realizing that glue alone would not be enough, but not wanting to drive either finish nails or staples into the wood of the front or sides, I decided on an approach that used 1/16” cardboard corner stiffeners that were glued and stapled (from behind) to the frame. Since the clamps are quite large, and frame corners are very near one another, I found that I could not do all 4 corners together. Therefore, I chose to connect 2 sides with 2 tops. When dried, I could now do the same and then marry the subassemblies together to finish 2 frames. The finished product looks very clean, is quite solid, and cardboard corner stiffeners provide a nice base for gluing or foam taping an inserted sign.
One caveat to be aware of: I made the mistake, on my first attempt, to trust the dimensional integrity of the wood. In reality, it’s best to allow a minimum of 1/16" extra space around the edges to allow for wood size variation. I found some craft panels (pre-cut to size) for example to vary as much as 1/8”. So the standard woodworking mantra of “measure twice, cut once” truly does apply.