It is a rolling base for the shelving unit, made, hopefully, to take the weight. Made out of off-the-shelf 1 x 6 poplar, dovetailed at the corners and (help me with this guys) through tenons for the cross braces (are these type of things called through tenons?).
I didn’t want the large-wheeled casters to show, so this frame allowed me to set them high and skirt them, allowing the space between the bottom of the unit and the floor to be only ¾ of an inch. I could have probably pieced it together with less wood, but I doubt it would be as strong.
I learned a few things while building this base but the one that stands out the most is; chiseling dovetails and through mortises in softwood is a bigger pain in the butt than it is doing the same with hardwood. Both the chisels, and the chisel operator, have to be extra sharp.
I finished one of the sides some time ago and finished scrapping the second one on Friday. It got coated with grain filler yesterday, which I hope to sand tomorrow. When it is completed, the assembly of the basic structure can take place, which should happen in a week or two – thank God!
It will not…I assure you…be soon enough.