Need help, want your opinion on my chessboard
For future reference, not mitering the corners only solved part of the problem with the miter joint opening and closing with the season, it did not solve the other problem associated with putting a border on the edge of a chess board.
The field and laminated base will move side to side. Attaching the short border on the field is a good move, but the way you attached the border to the two end grain sides is going to pose a problem. It may cause the field to split where the ends attaches because the long border piece is not going to allow the field to move freely.
There are two common ways of properly attaching a border to a chess board.
1) do it like you did, but only glue it in the middle of the end border pieces, and hold the ends in place with a brad or pin that will give slightly with the seasonal movement. Gluing it in the entire length is a problem!
Where the end border piece overlaps the side border piece, there will be movement so that the sides are only aligned part of the year. Other times the field will swell beyond the end of the border piece, other times the field will shrink so the end border pieces stick out.
2) do an end grain border on the end grain sides. That will require gluing up a panel the width of your chess board and ripping two border pieces out of it. Not as pretty with end grain showing along two edges, but it will not come apart. This method solves all problems associated with wood movement. This is my preferred method. You can even miter the corners.