Laying out a piece: every dimension starts from one end

The squared end is your 0. The tape hooks on once.

Start from the squared timber, longer than the piece. Before laying out anything, square one end: that is your 0. Every dimension on the piece starts from it, on all four faces.

On a face, hook the tape on the 0, once, and mark every line at its distance from that end: the start of a mortise, its end, a tenon shoulder, the peg hole, up to the cut-to-length line. Never measure from one line to the next: a misreading stays on its own line, it does not add up on every line that follows.

Cross dimensions are taken from the edge of a reference face, never from the opposite face. That is square rule: green timber off a mill does not have two parallel faces, so every joint is laid out at the same distance from the reference face, on the perfect timber inside — nominal minus ½ in.

Then hatch what comes off, as it shows on the face. Roll the piece on the sawhorses and do it again, face by face. A cut that enters through a face is drawn solid on that face; on the others, you find it dashed.

A well-made piece sheet has this form: each view is the whole timber, the 0 at the squared end, on the left on all four faces; every line carries its dimension from that end, and the extra length past the cut is hatched.