Measure the two front posts and mark with the wood pencil at 18½ inches.
Measure the two back posts and mark with the wood pencil at 36½ inches.
Cut all four posts across the pencil marks.
Cut the top ends of all four posts at a 45-degree angle, starting the angle ½ inch from the top of the post. This creates a small feature that finishes off the posts.
Chamfer the bottom edges of each post to prevent splintering through usage.
Measure and mark the position in which you wish to place the mortises in one of the posts. These should be at your desired height for the seat, the rails and the back.
Lay all four posts together on the work bench and use the tri-square to make sure they are even, and then mark the other three posts in the same position, using the tri-square to carry the measurements across.
Cut each mortise to take a tenon ? inch thick, 1¼ inches wide and 1 inch long.
Shoulder all eight rails on all sides to create a smoother finish and even the ends.
Lay the rails together on the bench, with the edges up.
Measure and mark the required length on one rail, then carry that measurement across the other rails and mark each one. This is the location of the shoulder lines for the tenons.
Take each rail separately and square the shoulder lines completely around all sides of each rail.
Cut the tenons to the measurements used above, so that they fit the mortises already cut.
Assemble the parts using good-quality hot wood glue, starting with the back. Set the back on a backwards slant to make the chair more comfortable to lean back against.
Assemble the front next, and then wait for both parts to dry before putting the rails into place.
Place the four slats evenly across the top rails to make the seat.
Secure each slat with wood glue.
Place the seat cushion on the slats and tie the two back corners to the back posts of the chair, to prevent the cushion from slipping.
Repeat the quantities and the process for subsequent chairs until you have made the number required for the size of the table.