Apply the wood glue along the cut edges, press the pieces together and hold the pieces in place with a
corner clamp. Glue and clamp all four corners.
Not so with
corner clamps: they automatically hold parts perfectly square.
Use wood glue and
corner clamps to join the corner sections of the frame.
*
Corner clamps are designed to hold miter or butt joints at a 90[degrees] angle.
To provide proper relief at the corners, release the
corner clamps and put two fingers under the screen at the corners and reclamp.
All orientations were kept constant for the warpage measurements, i.e., the corner defined by shrinkage measurements A and F corresponded to the
corner clamped in the warpage gauge between points 1 and 2.
(If you like, use
corner clamps or a stretch cord to hold them while glue dries.) Countersink and fill nail holes.
* Glue the frame together, using wood glue and masking tape (or
corner clamps) to secure the corners.