Cleat options ??

Is good, void free plywood, 3/4 x 3/4, a good option for cleats?? I am assuming that the standard softwood cleats are short due to wood expansion/contraction against the stable plywood case. Softwood probably also used because it was cheap and adequate. The original cab had 2 cleats per edge, each maybe 3 inches long each (about 1.5 inches for the flat side against the case). If plywood is a good option, it seems I could run it the full length of the edge (baffle to cabinet back), and it might well be much stronger than the 2 softwood cleats.

Any personal experience in this, or opinions (silly question, I know) ??

Sorry if there is already something on this on the board - search function seems to be on the fritz....

regards -- Roger

Hi Roger.
A couple of comments:

1. Neither hardwood nor softwood expands/contracts along its length to any significant degree. So extending the cleat is not a problem.
2. The original may have been a "rub joint", where the short cleat length is dabbed with glue and rubbed back and forth along the joint until the glue grabs. No nails, just glue. Easier to do with short lengths than one long one.
3. Probably the more important issue is the adhesive you are contemplating. Enclosure walls are rarely at perfect right angles, and neither are cleats. There are gaps to be considered. A proper gap-filling hard setting adhesive is what you want. Yellow/white glue doesn't span gaps, and is not great unless the joint is well near perfect. Same with Gorilla type glue. Locktite PM is pretty good. Epoxy WITH ADDED THICKENER is probably the best, if you can deal with the time, money and mess. West System Epoxy works well in this application. Don't forget the thickener ("micro balloons").
4. Consider knocking off the cleat's corner into a chamfer shape to help set the cleat into the corner. Fitting a right angle into a right angle is not easy.

My favorite for this application is baltic birch or oak. Both are stiff, and glue really well. Softwood, as from the home center, is usually not really well dried and tends to shrink a lot across its thickness and width.

I hope some of this helps. Best of luck.