Monday, April 4, 2016

Extreme wood bending

I really like old airplanes and I ran across this video about bending wood for airplane parts that is extremely interesting.  Obviously, there are few applications for bending wood more critical than the fuselage of an airplane.  Add to that the fact that parts often have to be bent at sharp angles and you have a real challenge.  There are some worthwhile lessons here for woodworkers even if we aren't going to fly around in our projects.  I'm already thinking of things I would like to try making.

Several comments.  He achieves these very sharp angles by laminating and steam bending in combination.  First he steam bends 1/8" pieces, then he laminates them together.  Notice how basic his steam bending apparatus is, just plastic pipe and a wallpaper steamer.  I am fairly sure this is Sitka spruce by the way, favored by airplane makers for its strength, durability and light weight.  Think about the stresses on a WWI fighter.  I was also interested in his jig, a lot simpler than most I read about.  Finally, I had never heard of casein glue.  It is made from milk protein and is apparently very strong, durable, resistant to water and has a long open time.  Invented in ancient Egypt, it has been used by musical instrument makers and wooden airframe manufacturers.

Here's the video:

 Correction:  Alan correctly points out in the comments below that the woodworker in the video is using Cascophen glue, not casein as I indicated.  As he says, it is a resorcinol formaldehyde adhesive that has apparently come to replace casein for manufacturing wooden airframes.  I apologize for the error.  The information about casein glue above is still correct.


  1. I wonder why this glue never caught on? After reading how it is made it is certainly a lot easier than hide glue. Maybe it was because of it's longer cure time vs hide glue's shorter set up time.

  2. I read that it has been supplanted by formaldehyde glues, which are apparently more moisture resistant. Not sure this was a net gain.

  3. He is not using casein glue. He's using cascophen glue (see about 6 min in). Cascophen is a resorcinol formaldehyde glue.

  4. Wow, a really intensive process. I was hoping to see a hand plane to get it to thickness. Oh, well, I can't blame him.