I had a very productive day yesterday. I soaked the linings in warm water then trimmed a bevel on one side of each. This was surprisingly easy with them damp and flexible. I notched the corners of each corner and end block, then bent and trimmed the linings to fit. I left them in place and lightly clamped while I mixed a new batch of hide glue. Once the glue was ready, I removed the lining pieces one at a time, glued them and set them in place.
A few hours later, I removed the clothespin clamps and sanded the linings flush to the ribs. The next task was to mark and drill the locator pin holes. These allow reliable alignment of the plates to the ribs as work progresses. They are at the top and bottom on the centreline, just inside the ribs in the end blocks.
With the locator pins in place, I traced the perimeters twice, once flush to the ribs and once with a 3mm offset using a thick washer. The inner trace line was highlighted with a red pencil, the neck location marked, and the C-bout corners extended. I repeated this with the top plate.
Over the next week I have to recreate a set of scroll templates, as I can't find the original ones. Fortunately I have a poster with all the critical layouts and dimensions, so hopefully I'll be able to get a photocopy onto acetate and cut them out full-size.