Bread boards are one of the best ways to counter cupping. Used predominantly in tables, they serve an abundant number of uses. I like them for case tops, especially with un-anchored tops like I use in a lot of my cases, where the top is hinged in the back to create a hidden compartment in the top in which case the top is just floating, so bread boards are a nice way to keep it stable.
The Jefferson Joinery was fond of the mitered ones. I like them as well, this technique is seen a lot on Colonial American furniture. Very popular for the drop front on a Slant Front Desk. Basically, bread board is done by creating a tongue (tenon) on the primary top, then a mortise or in this case a groove, my tenon and groove are 7/8″ thick deep by 1/4″, then it is pinned or pegged on. In the case of the miter, a separate piece is added to the front of the top and extends beyond the ends enough to allow for the end miters, then it is glued in place. Then the bread boards are installed. I fit the bread boards and then drill 1/4″ holes through the bread board and tenon, then I remove the bread board and ‘slot’ the hole on the tenon so the top can expand and contract. Keep them clamped tightly when you drill the holes so no ‘slop’ is created. Also be careful as well, slotting the tenon holes. I usually go about 3/32″ on each side of the hole to slot.
I then put it all together, a tenon or biscuit at the miter join and glue, I also glue about 1″ of the front of the bread board. NEVER glue the bread board completely, that only defeats the purpose of using this technique. Then I clamp it all tight and drive 1/4″ pegs in the holes and it’s done.
I did the same thing on the seed press top, in both cases, I allowed the tenon to show in the back. If it’s a straight bread board like a table, or going to receive a routed profile on the edge, I do a blind one where I trim the tenon back 5/8″ or so and use a blind mortise so no tenon shows on the end.
In the case of the seed press it was done because the top simply floats. The desk, because the original was this way. The top will be secured to a base so it wouldn’t be needed. The original top moved I suspect, either lifted or rotated, not sure. In the case of the straight end bread boards on tables, I glue the center about 2″, the rest is pegs. Pegs as a means of attachment are excellent, been working for several thousand years now.
Got to get to the gettin’ Later!