To try and spice this blog up a bit, I thought I would outline the process of cutting and fitting the rib parts. I have already discussed my gluing-up process.
I apologize for the varying color balance of the photos. The primary objective was to get the rib built. I have various lighting sources in my shop, and the camera was thinking on its own regarding operation of the flash. I am sure there are adjustments in the camera to force flash on every exposure. But I was not interested in taking the time to figure it out.
The very important first step is to clean off the jig. Usually, the problem is just a bit of dust and wood chips. It is very important that the capstrip snuggles down flat onto the jig surface. It is also important to make sure no dried glue drips are lurking where capstrip will go.
After cleaning things up, it is time to place the blocks. This rib is an "aileron" rib, so it has both a nose block (shown in this photo) and an end block (shown in the next photo). It is important to get the block fitted properly in the jig.
Here is the tail block placed on the jig in its proper location. Due to a minor discrepancy in the jig used to cut these blocks, they all need a bit of adjusting to fit correctly.
The first longitudinal member to be cut and fit is the bottom one. It fits into a notch in the nose block at the front end. The end of the capstrip is carefully marked to match the angle of the notch.
The tail of the longitudinal member needs to be marked for cutting, too. This is not a critical dimension. The capstrip just needs to extend beyond the last securing cam beyond the tail block. The capstrip will be trimmed to final length after the first gusset is in place.
The bottom longitudinal is cut to rough length on my cute little miniature table saw. This is a handy tool for rough cutting where both ends of the piece are longer than the throat of the band saw.
The angle on the front end of the bottom longitudinal is trimmed to shape on the disk sander.
And the bottom longitudinal is in place.
Just like the bottom longitudinal, the front of the top longitudinal needs to be trimmed to fit into the notch in the nose block. Marking is a simple process of lining up the capstrip and extending the notch angle onto it.
The next step, after trimming the longitudinal, is to secure it in the jig using the cams. What you can't see here is that my fingers are pushing the capstrip down firmly onto the jig. All the capstrip has to be completely flat on the jig. The tail of the top longitudinal is measured for the rough cut with the capstrip completely installed in the jig to make sure the curve of the top longitudinal doesn't result in cutting the capstrip too short.
I mentioned earlier that the tail block needs some final trimming. In this photo I am making a pencil line along the bottom edge of the block. The idea behind a lot of these pencil lines is to serve as an indicator. By sanding off just to the point where the pencil line disappears, I avoid taking off too much material. If too little is taken off, I simply make another pencil line and repeat the process.
Here is the tail block being trimmed. Because the front edge of the block is perpendicular to the bottom longitudinal it makes sense to use the miter gauge.
Perfect fit! It is important that these parts are friction fit between the longitudinals without pushing the capstrip out of position.
Here are the two longitudinals installed on the jig ready for the verticals and the braces.
This is a glimpse of the shelf on my work table. I keep the hand tools and buckets of gussets handy so that I am not wandering around the shop looking for parts and tools.
Marking the first vertical for trimming. This is a pretty simple process of lining the capstrip up, sighting down onto the top longitudinal, and marking the vertical-to-be aligned with the bottom edge of the top longitudinal.
The vertical-to-be is trimmed. Note the penciled arrow. I mark parts that have only one orientation with an arrow pointing to the top of the part. This really helps keep things straight.
The bottom of the vertical is marked to length at the bottom longitudinal.
The vertical is cut to length, at least the first cut, is done on the band saw. I always make this cut on the waste side of the pencil line. The part always turns out a little long. Thankfully.
And, predictably, the vertical is just a bit long.
I make a pencil line right at the end of the vertical, just a lead-width wide.
And it is trimmed. In these instances I just sand down until the pencil almost, but not quite, disappears.
Still just a bit too long. So another pencil mark is made and back to the sander.
Perfect fit! The business card is serving as a shim. Tony Bingelis recommends that when installing the verticals next to the spars (represented by the 3/4" plywood filler) an allowance of .010 to .015 be made so that the ribs can be slid onto the spars. The business cards measure out to .013.
The 1/4-inch shim between the cam and the vertical is there because some of the ribs require double verticals at the spars.
All of the verticals are cut and fitted using the same process.
Now its time for the braces. I place a length of capstrip in the location for the brace for marking. This first mark is aligned with the vertical.
And a second mark aligned with the top longitudinal.
I rough cut the braces to length so that they are easy to handle and the bottom angles can be trimmed on the sander. The sander works much better for these angled cuts than a saw.
The bottom of the brace is rough cut on the band saw.
On the top of the brace, first one angle is cut...
Then the other. Again, note the arrow to keep straight which end is the top and which the bottom. When one is cranking out braces, it can get confusing as to which end is which.
Then the bottom end is aligned and marked for final trimming...
Like so...
And, after a couple of trips to the sander, a perfect fit. Well, almost. If you look closely, I have made a mistake (not an unusual occurrence) that will result in my having to make another brace.
That's right. The shim on the vertical next to the spar is on the wrong side of the capstrip! I have to watch myself all the time.
The rest of the pieces are simply repeats of these steps down the length of the rib. Once all the pieces are in place, gluing gussets can begin.
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