The Ribs are Complete!

Thanks to Norm Brody for assisting today in laminating the last of the half ribs.

Here is a shot of the full rib in approximate position (that's Sean holding the rib; you can see Norm's right arm at the right of the photo, he having narrowly escaped the shot):

Here is a view of the last 8-ply rib section that we layed up today:

Since we decided to create half-ribs rather than attempt to lay up full ribs, there is a point where the half-ribs meet.  Here is a drawing detail of the junctures:

Front is to the right.  The left partition is floor-to-ceiling and separates the cabin from the galley.  The rightmost partition is shown only partially; it will be wall-to-wall but only 24" high and will create cabinet space inside the cabin.  In both cases the plywood partition will be backed on both sides by oak solids.  The oak boards on both forward sides of the partitions, and the aft side of the forward partition, will be in essence "yokes" - notched to receive the ribs.  The aft side of the aft partition will become the hatch hinge mounting point.

"But,"  you ask, "why do you have two junctures?"  Simple:  the lengths of the oak slats as provided couldn't support the front section running all the way to the main plywood partition while simultaneously having one-piece plies.  We had realized during our test lamination (the one full rib) that having a joint in a ply was to be avoided.  In order to run to the aft partition above we would have needed many more slats over ten feet long.  Consequently, the cabinet partial partition became the main juncture.  This also means that the interior aft ribs will be cut into hatch pieces and stationary pieces running between the two partitions.

Structure - An Ongoing Conversation

As I mentioned recently, the design of the lattice - the ribs and the cross pieces (I called them stringers, in roof structure terminology they are purlins) and how to join them is an ongoing conversation.  Today, Norm Brody offered yet another solution that has promise.

The detail would be to create two half-thickness purlins with groves down their middle - essentially a 3/8" x 1-1/2" piece with a 1/4" wide by 1/8" deep groove, all by 5' length.  These halves would be glued together, creating a member 3/4" x 1-1/2" with a 1/4" square hole through it.  They would then be cut to length to fit between the ribs, and corresponding holes drilled through the ribs.  For assembly, we would take a long enough threaded rod and insert it through the first rib, through the fabricated purlin, through the next rib, through the next purlin, etc., and use bolts and washers on both ends to draw the assembly tight.  The holes on the outside would be counter-bored to accommodate the diameter of the washer and the depth of the washer and nut.  The rods would be cut to length so as to be buried inside the structure and not visible once the side panels are added.

This technique has promise, but since we aren't ready to do this tomorrow, anything can change.  First we need to clean up the ribs and split the center ones (built up 1-5/8" thick but each individual rib is to be 3/4" thick) and lay out the sides.  With the side layouts in place we can then lay out the cross-members.  So, other ideas may present themselves in the meantime.