More Process, Splines
Inner frame, see below, from the back showing the inlet splines. This was almost a signature of Newcomb-Macklin frames. I run the mitred sections over a 1/2 inch groover on the tablesaw, before joining them. A stop is clamped to the saw, at half the size of the spline, all of one side being milled at once. I use both 1/8 inch and 1/4 inch plywood for the splines, slightly oversize so I can plane them to fit. Glued with hide glue and nailed.