Rails are cherry, 1 3/8 thick. Posts are 2 1/4". I understand the 1/3 rule but, since the load is vertical, across the grain of the domino, I thought 14mm would be best. I had planned on using 100mm dominoes, 70mm in the rail and 30mm in the post. The foot and head board rails will be glued but, the side rails will have both dominoes and a bed bolt. I had been thinking that 2 dominoes in each rail, offset for the bolts might work? I'd rather not drill a hole for the bolt through any dominoes.
Working between Imperial and Metric is a hassle are there any Imperial kits available for depth, etc?