Thanks Mark for the new formula. I have been following the general guidelines for shouldered dovetails. I was wondering by following the joist or purlin ¾ rule I would have to use the notched member calculation and this isn’t mentioned in the formula. Then looking closer at the 5/8 rule in the book I began to wonder about the meat under the shoulder. Would this be verified with the single shear formula (AxS) and would I use the Fv Shear parallel to the grain.