Interior framing

With the horse now glued to the baseboard, the interior framing continues with the gluing of the knees. I traced out the places where I wanted them, making sure that they were at right angles to the edge of the baseboard and exactly flush with the edge. Getting a right angle was easy on the spine and tail, and as for the bentside, I basically eyeballed the knee placement there. There are 8 knees on the bentside, spaced a bit closer together in the treble where the curvature is tighter and more widely towards the bass. The spine is supported by three knees, and the tail has one in the middle.

Before gluing the knees, a pair of small holes was drilled through the baseboard to mark the correct location for dowel holes drilled from beneath, as mentioned earlier.

The knees were glued with polyurethane glue. The back corner was fastened with a single brad, while the front was clamped:


Using a pneumatic nailer was very helpful, as I could hold the knee in place and have it instantly nailed down at the back without things shifting around.

Note the two corner blocks at the tail: these will be the endpoints of the spine and bentside liners.

When the glue dried, lots and lots of holes were drilled and dowels fitted: 3/8" dowels to hold the underside of the wrestplank support blocks, and 1/4" dowels to hold the knees, corner blocks and lower belly rail edge.

Next, the spine liner was glued in place:


This is joined to the bass wrestplank support with a pair of dowels and is cut short of the tip of the instrument by the width of the tail liner (seen resting loosely on the opposite corner block). The tail liner will overlap both the spine and bentside liners to keep it from shifting under string tension.

Having prepared the tail liner to its final dimensions, it gets glued on next:


Behind the tail you can see my length of door stop composite lying on the spine liner. It will help me in getting a preliminary idea of the bentside liner's curvature.

Making the bentside liner will be the tricky part: it will be kerfed (i.e. a bunch of saw cuts will be made most of the way through its thickness) to make it flexible, and is likely to require some trial and error to determine how to best do it. I have a spare piece of poplar lying around to practice on before I try this for real.