I had duplicate sheets of the plans made at a blueprint shop so I could cut out the full size patterns. If you make copies, make sure that the dimensions are not changed in the copying process.

I cut out the patterns and glued them to 3/4” MDF to make the forms.

Next, cut out the form block on a band saw. Note that this block has the flanges still attached to the basic shape. This is because I am going to use the router method to finish cut my rib blanks.

OK, here’s the setup. On the left is the template block with the flanges included in the shape. In the middle we have rib blanks cut from the stock material with snips, leaving 1/8” - 1/4” extra outside of the finished dimensions. On the right is the backer block for holding the sandwich while routing.

I typically routed 4 to 5 blanks at the same time. Here’s the sandwich being assembled. The bolt heads must be countersunk into the backer block to ride smoothly over the router table.

The sandwich prior to routing. The bolts go through the jig holes in the blanks. The holes at the base of the flanges have been pre drilled while in the blocks for uniformity.

DANGER! DANGER Robinson Family! That flush trim bit is just waiting to eat the end of your finger off! Work the piece into the bit slowly. I wore heavy gloves to protect my hands if (when) the bit grabbed the piece and jerked it about. Wear a full face mask and long sleeves. The chips come off fast and hot. I put a cardboard box around three sides of the router table so I only had to clean up a small area instead of the whole shop. Oh, and earplugs were nice too!

Post routing. I used snips to finish the cuts between the flanges. I didn’t have a bit small enough on hand when I got to this piece, so I went ahead without it.

Blanks with a trial finished rib. I highly recommend the router method of cutting blanks. The uniformity greatly aids assembly later on.