Thursday, October 23, 2008



Have you ever wondered why tabletops often have perpendicular end boards? Is it structural? Is it purely design?

Well the end boards are called “Breadboards” and they are both for design and structure.

Beauty is in the eye of the beholder, but I like it. To me it makes the table top look framed and purposed. It’s not just boards that have been lined up and glued together. Traditionally, end grain was thought to be aesthetically poor. Breadboards allows you hide the majority of the end grain of the main boards and replace it with two smaller portions at the end.

Structurally, they are designed to help prevent the tabletop cupping. As wood expands and contracts with the passage of time and the moisture content acclimatises to the environment the perfectly milled boards may warp, cup, twist, and do all sorts of things. Similarly to attaching an underlying brace Rigid breadboards hel

p to reduce cupping by keeping the boards in line. (Although this is what most people would say I’ve heard Christopher Schwartz teach that he’s doubtful as to how important this is. Youtube Link.)

You can attack breadboard in a number of ways. The most important point to remember is the direction of wood movement. Throughout the year as the moisture content changes solid timber expands and contracts. Different timbers expand at different percentages. The majority of expansion occurs in the plan perpendicular to the long grain. When you design your joinery it must allow the main boards to expand and slide and it must remain attached to the end.

Tongue and Groove
The simpliest joinerty is to use a tongue and groove. This can be down with a router or saw and cleaned up with a shoulder plane and sandpaper.

Stopped Tongue and Groove
Often its preferred to hide the joinery. Simply stopping before the end achieves this with little hassle. The groove cannot be cut on a tablesaw but a plunge router, drill press or hollow chisle mortiser will be effective. This is the plan for the shaker table.

Sliding Dovetail
Essentially a modified tongue and groove joint which prevents one direction of movement. Dovetails are a mark of good woodworking and most people like the look. This would be my favourite design.

To cut the bread board, remove the bulk of the material with a table saw or straight router bit smaller than the desired dovetail. Then with a good quality dovetail router clean out the groove.

The table side is a little trickier. The best way technique is to use a straight bit and a edgeguide to remove the bulk of the waste. Then you a dovetail plane to finish the job. Derk Cohen has wonderful article on his dovetail plane.

You can also used dowels or loose tennons (such as dominos). You need to remember however, that they must allow room to slide. Dowels I think are too tricky and I don't have access to a domino (but I hear it's very good for this.)

Hope that helps...

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