Wednesday, October 11, 2017
A Freed Rib, or Six
The plates, top and back, are done to the point that they can be glued onto the ribs. So this means the ribs have to come off the forms. I have linings both top and bottom, the first step for removal is to trim these from square to tapered. All sorts of ways to do that. What you basically want is a big surface at the outside, to create a bigger gluing surface, tapered down to thin on the inside, to reduce weight and stiffness.
I take a compass and set the pencil at about half the width of the lining, in the vertical sense, and trace out a line on the linings all the way around, top and bottom. Then a sharp knife, cut a bevel from the line to the inside edge, tapering down to meet the rib. I usually make a few nicks on the form and on the ribs, but nothing so much to worry about. And it doesn’t need to be perfect right here, because I’ll clean it up later after the ribs are off the form.
Once the linings are trimmed, I use a small hammer and knock the blocks loose from the form. Then a flat chisel, I strike diagonal cuts to take out the ‘inside’ corners that will disappear anyway.
When those fragments are out, it’s a matter of carefully loosening the ribs -- may have a few accidental glue spots that you don’t want to rush loose -- and then bending the ribs outward a bit, tipping the form as you go. I start at the C-bouts and work towards the larger, lower bouts. Once the endblock is free, you’re pretty much done with the removal.
Then, trim up the blocks and clean up the linings a bit.
Next, glue on a plate or two.