New Ribs

I had the opportunity today to start the process of fabricating the additional 14 ribs.  Recalling an earlier post, I have decided to replace the leading edge ribs with full ribs.  Though I have more than sufficient material on hand, I need to turn that material into the various small parts that make up a rib. 

The first step is fabricating the rear end blocks.

I decided to build these blocks using the band saw and the sander instead of cutting them out using the router.  I just didn't feel like reconfiguring the shop for the router operation (a big disadvantage of a small shop, things have to be re-arranged for different operations) and I feel confident in my skill with the band saw and sander. 

Task #1, above, is to cut a pattern.  Using a single pattern is preferable so that any variations are not magnified from copy to copy.  The pattern takes particular care to ensure it is accurate. 

The above photo shows the pattern, cut from plain ole 1/4" ply, as opposed to aircraft grade.  All of its dimensions have been checked. 

The photo also shows the outline of the pattern traced onto 1/4" aircraft ply.  I had these squares left over from a previous mistake.  :)

I have found it advantageous to think out the production process, rather than considering fabricating one item at a time, so that all the parts are ready to hand when it comes time to fabricate the rib.  Thinking in terms of production instead of piece-by-piece fabrication really speeds things up and ensures a more uniform finished product.

Next I drew guidelines to cut the square into individual rough blanks.  Even when doing a non-critical cut such as this I find it helpful to draw lines.  It keeps me from making monumental mistakes...most of the time.

Here is the stack of blanks after cutting them apart on the band saw.  There are actually 16 blanks here.  I only need 14, but having two extras gives me the opportunity to make two mistakes without having to cut additional blanks and/or blocks.

The finish cuts are made on the sander.  The straight cuts get done on the disk...

The inside curves are done on the belt. 

A finished end block.

After a couple of hours of work, a stack of 15 end blocks.

But wait.....didn't I say I started out with 16 blanks???  Yep!  A small cutting mistake turned one of the blanks into scrap.  It always pays to plan for mistakes.