need help with double sided hanging HDU sign?
Lets assume that your customer wants a double-sided, hanging sign, either carved or sandblasted. Lets further assume it will be 4" thick, but it could be 1" or 6". We’ll make this one a 3’x4′ sign.
Using a 1/2" round bottomed router bit, cut two channels 1/4" deep the entire height of the sheet, top to bottom on the back side, 1′ in from either edge and 2′ apart. Cut two matching channels on the backside of the second sheet.
Placing the sheets back to back you should have two 1/2" holes running from to to bottom through the joined center. Slightly oversized is ok.
Taking two 1/2" x 4′ long rods, insert them through the holes to make sure they fit. Weld a 4"x4" square steel plate to the bottom of each rod. You could also use "all-thread" rod and tap the plates to screw to the bottoms.
Bend the top of the rod into two "J" shapes as hangars. Assuming the signs are now finished, lay a liberal amount of PB240 into the two channels and lay the rods into the channels of one sign. Coat the entire surface of the first piece with PB240 and overlay the second sign, aligning the channels and edges.
Rather than clamping, lay several heavy boxes on top of the sandwiched sign and allow to cure for 12 hours. Watch for any adhesive expanding out of the edges and wipe it away. You may have to do that a number of times, but keep in mind that PB240 expands tremendously, so don’t get carried away with the amount you use.
Gorilla glue is a similar adhesive, I’m told, but I have no experience with it.
Now when you stand your sign on end, you have a piece that is supported by the entire sign itself, and not by just a pair of eyescrews into the top.
My daughter just reminded me that we have also bent the rod into a 90 degree inside the sign near the bottom. You just have to cut your channel to fit that bend, but that does work too and saves welding or threading. The whole, bonded affair makes for a very strong sign that is stronger than the original material itself.
One last point………….make sure that the two "J" s you bent into the top of the rods as hangers are both pointing the same direction! I think you get the picture.
One point I forgot. Could it be wood rather than HDU? Of course. Why not? Methodology is the same.