Customizing trailing edge balsa stock

There are lots of plans that call for trailing edge stock in the wings.  It’s a very common item, so as an avid scratch builder I like to have several sizes on hand…. but unfortunately I usually don’t have several sizes on hand.  What I have instead is a whole bunch of one size. I bought a guy’s hobby collection a long time ago and got dozens of pairs of 1.5″ trailing edge stock.  I’ve been chipping away at these for years and I still have a lot of them left.  The good news is that the wood quality is very good, so they’re easy to work with.

I’m currently building a Baby Buzzard, which calls for 3/16″ x 1″ trailing edge stock in the wing.  Although I happen to have a couple of pieces in the correct size, one piece is really hard and the other is really soft.  I don’t want my wing to be out of balance, so I’m not going to use them.  Instead, I decided to cut some big trailing edge stock down to the correct size.

If you have wood that’s not quite the right size, don’t let it push you around.  Teach it who’s the boss.  You can even make trailing edge stock out of regular sheet wood 1/4 or 3/8 inch thick, or from multiple pieces laminated together to make the required thickness.

Here’s what I started with.


First I marked it so I could cut it an inch wide.


Because the wood has a tapered cross section I had to support it on top of another tapered piece to make it flat on top.


Then I put the metal ruler on it and cut it straight down, holding the knife vertically.  When you’re cutting something thick like this don’t try to cut it all in one pass.  Cut it a little bit, then go back over it and cut it a little bit more, etc.  Maybe cut it in 4 or 5 passes.  Here’s how the trimmed piece compares to the original size.


It’s the right width now, but it’s still too thick.  My plan calls for 3/16″ thick, and this is piece is more like 5/16″.  I’ll have to trim 1/8″ off at the thick edge.  The thin edge looks about right.


I don’t want to go at it with the sanding block right away.  That would take a lot of sanding.  So I’m going to use a hobby sized planer.



It’s a good idea to shave a little bit, check the thickness, shave a little bit more, check again, etc.  When it’s close, stop shaving it.


Now it’s time to sand.  Put the thin edge at the edge of the table, hold it with your less talented hand, and start sanding.  You’ll notice that you can’t sand the other end very easily, because your hand is in the way.  You can’t turn the stick around because the taper would make the sanding block hit the table.  DSC_0600

Put an extra piece of trailing edge stock in place at the edge of the table as if you were going to sand it.  Take the piece that you were working on and turn it around, and put it on top of the extra piece so the top is flat.  Now you can sand it easily.

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It’s a good idea to get a piece of wood the correct thickness (the thickness that you’re aiming for) and set it on the table.  Compare the thick edge of your trailing edge stock to your measuring stick frequently so you don’t sand it too much.

Here’s what the finished piece looks like next to the original.  You can see that in addition to the reduced width, the taper angle was also changed significantly.


Now I have the exact size that I need for the plane I’m building, and I also have some oddly shaped sticks.

DSC_0599These will be used as reinforcement around landing gear blocks, next to bulkheads, and behind firewalls.  It’s also great for reinforcing wing bolt blocks.  Any time the plan calls for trailing edge stock, triangle stock, 1/4″ sticks, or any other such thing for corner reinforcement in the fuselage, the shape really isn’t critical.  Jam some of this stuff in there and save yourself a little bit of cash to put toward the next jug of fuel.

One final point:  This idea works not only for making big trailing edge stock smaller, but also for making small trailing edge stock bigger.  You can laminate a strip of sheet wood to one face of a piece that’s too thin, and then sand it to the correct taper.  Or you can add a fat stick to the thick edge to make it wider.  Balsa wood is great stuff.  You just stick pieces together until it looks like what you’re trying to build.