Steam Forming 1/8" Birch Plywood Wing Walk

I found the 1/8" plywood was too stiff to bend to the curve of the nose ribs without steam to soften it.  Actually the trick is not the steam it's the heat provided by the steam which softens the cellulose fibers in the wood.  If you have a big enough oven it would work fine.  Soaking in water is not the answer.

 The wing walk is 12" wide so I cut an 8' 2x4 into 12" pieces. On the first piece I drew the curve of the 1/4" solid rib from the nose back.  It is shorter than a regular rib by the thickness of a 1/4" cap strip.

The notches are to allow clamps to be square to the upper surface, for a better grip.

All the cuts were made with the band saw on the Shop Smith.  Then the shape was drawn on the rest of the blocks and back to the band saw.

 I glued and nailed the stack together, using a square to keep all the blocks aligned.

 I put a new 80 grit belt on the sander and squared the table before evening the surface to the line at each end.  Slow and careful.  It worked out well.

I evened up the underside clamping surfaces, so the clamps would set even.  I sanded the middle section.  For the 2 ends I stood the block on edge and ran it through the table saw with the curve against the fence.

  The idea for steaming was to put 1/4" of hot water in a heated cookie sheet, with permission of the boss.  Set it on the stove with the heat so it's just below boiling.

I heated it until there were good small bubbles on the bottom of the pan.  The thermometer said it was at 160 degrees.

The block at the right is to support the plywood so the pan stays level.

 Then set the plywood on the pan so 1/4" to 1/2" is sticking out.  You don't want it falling in the water.

Another heated pan was set carefully on top and the whole thing covered with 4 folds of a beach towel for insulation.

Don't light the towel on fire.  I wouldn't try this on a gas stove.

 The block and clamps were positioned and ready for quick action.  I steamed the wood 15 minutes and it was soft enough to form to the block by hand, just like steaming the rib capstrips.

Work fast.  The book says you have 5 seconds.  You need an assistant.  The grip clamps were much easier for this than c-clamps.

 It's a good tight fit to the block.  It will cool and dry for a day before taking it out, again like the capstrips.

Hopefully the spring back won't be too much for gluing it to the ribs, etc.  We'll find out tomorrow.

This worked so really good.