Wood joinery was an interesting assignment that made me think of the CAD and CAM process to the last detail, and I decided to make an object that has good amount of joinery. I made a crate (14″ x 10″ x 8″) from plywood.
The drawing was simple, but I had to be careful and make sure that the notches will align. The most important part was the corners where three surfaces meet together- calculations involved thickness of the material, tolerance, and length of the notches. I designed the joins so that the opposite walls are identical pieces, like the ones on left and right with handles, as shown in the drawing below. I used mirror images so that top plywood surface texture and color would show on inside of the box, and bottom surface of the plywood becomes the outside.
The tolerance worked perfect: the notch length is 1.98″ and corresponding indentation is 2.02″. That is NOT good enough gap for two pieces to join together without glue; but with 5 pieces and 8 edges it just perfectly worked. Next I cleaned the cutouts with sandpaper, applied glue and clamped the pieces together for a day.
With glue, it got a little more tighter and fitting in the last piece was a little difficult, but I didn’t have to file or sand down any surface in order to join it together. A minor error was the top edge engraving on 4 walls that creates a little 0.25″ step for a lid: On longer walls I forgot to engrave the extra 0.25″ on each end to compensate for shorter wall engraving, and it looked like this:
I had to use chisel and hammer to subtract a little 0.25 x 0.25″ square.
Next I used sandpapers to clean the edges, and handheld sander tool to clean the surface. This tool was effective in almost completely removing the stains where the glue had popped out of he joints, forming a bulge after drying:
Following is the before and after image with the stains removed.