Mo, If I understand you correctly, you are thinking that the brace will be pushed further to the inside of the frame by the bow? That would only be true if you were using mill rule and basically measuring the depth of the brace mortise from the surface of the post timber that the brace rests against. With square rule as I currently understand it, you would measure the depth of the mortise from the reference chalk line(s), which is not bowed. You are thereby placing the brace into the timber relative to the "perfect" inner timber. You've created this perfect timber with your chalk lines, which you are measuring from, and you house your brace so that it's face will rest against a correctly positioned face(not the outer bowed face of the timber) which you create relative the "perfect" timber. It's all beginning to make sense to me now. Now I just have to get to practicing it! I plan to prep reclaim timbers in Feb and try to get a design on paper by the end of Feb so I can start layout in March.