HDU sign attachment to steel frame

[cnc_fabricator11]

Hello everyone,


We've been working on a fairly large sign project for the past few weeks and we are still exploring possibilities of attaching the sign to its steel frame. I've attached images below of a drawing of the steel frame and images of the cut hdu. There are two of these HDU signs (only one is pictured below) roughly 8.5' x 5.5' and will be attached to both sides of the 1 x 4 tubular steel cross brace that is highlighted in the steel frame drawing. First question, we will be attaching an MDO backing to the HDU and we were curious what method would be best to join together MDO pieces in order to cover the 8.5' x 5.5' dimension of the sign? Second question, we had the idea of incorporating a french cleat onto the tubular steel cross brace to essentially hang the sign but we were wondering if anyone else had other ideas on how to attach the HDU to the tubular steel cross brace?

Any suggestions would be most appreciated,


-Patrick

[dakers]

like the french cleat. we have joined mdo with biscuit joiner and recorcinol with success. would attach mdo to steel frame attach the hdu to mdo with french cleat. or as many have done ( we have not tried this ) glue alumacorr to the hdu and then french cleat to the steel. HDO is better than MDO.
for exterior signs not under a roof we do not glue wood to hdu but look for other options

[dakers]

here is one we used the cleat on. the cleat was hdu that we made and glued to sign and attached to building with mechanical fasteners.
it has been up for about 15 years now with no problems.