Hi,

I’m in the process of building a countertop that will measure roughly 11′ by 2′ wide from two, 12′ wide pine boards. I’m considering using 8″ to 10″ wide bread board ends for two reasons: length and stability. The long 12″ wide boards are too short by about a foot and bread board ends can/will make up the difference, but they need to be wider than i’ve seen in other pieces of work.

I was thinking that i could mill/use 12mmx140mm dominos and then rout 1/2″ deep tenon on the long boards and a 1/2″ deep dado on the breadboard ends. The tenon/dado combination would be good if any gaps occur over time, but the strength to resist cupping should come from the dominos. The thickness of the counter top is likely to be 1.5″ thick so a 12mm thick domino should be ok, but how thick should the tenon be going into the breadboard end?

Also, i’ve heard a rule of 2/3 for the depth of the mortise to the width of the breadboard end.  How “dead fast” is that rule? Do i really need to extend the domino into the breadboard end?

If i need to, i can always rip the breadboard in half and use the domino to mill out a slot of the appropriate length. Then glue the two pieces of the breadboard back together, but is it really worth it?

The pine boards come form an old property where we cut down several trees, milled and air dried the lumber about 20 yrs ago. So the boards, although short, is what i’m going to use.

Interested in any suggestions,

Kevin