Sunday, April 23, 2017

Steam-Bending Stringers

Things went fairly well on the first stringer, except for a couple minor hitches.
A little hard to see but here is the bow section of the plans "lofted" onto a piece of poster board.  (I had to tape a small piece in the lower left corner to get the whole thing to fit.)

I forgot to take pictures, but I laid the poster board on a piece of 3/4" plywood and drove a finish nail at each station point.  The station lines are the vertical lines in the drawing, 6" apart.  I then used a thin piece of wood as a "spline" and bent it around the nails to guide my pencil.  I cut out the curve on the plywood and drilled holes for  the clamps.

The steam generator is busy pumping steam into the steamer box.

This is just a meat thermometer.  The temp is exactly 212 degrees. 

Looks like I should have used thicker wood!  This is only 1/2" lumber.  The temp dropped to about 208, then I put some duct tape over the split and got it back up to around 210 for the last few minutes of steaming. 

The split did not cause any problems.  The wood bent very easily around the form.  Here you can see it clamped and ready to set aside for a day or so to cool and pretty-much retain it's shape.  I could put thicker doors on the box for the second stringer, but I think I'll try the PVC pipe method that a lot of people use.  More about that in the next post.





1 comment:

  1. I was concerned about that or at least that the pipe would sag, so I ran a test today. First, I put a groove for the pipe to sit in, in a 3' board to prevent sagging and to keep the pipe from rolling. There is a block under the front end of the board so water will run out the drain hole in the back of the pipe. I hooked up the steamer and ran it for over an hour after it reached 212 degrees with no ill effects. The pipe was still quite rigid so I don't think it would have sagged. I'll write all this up more thoroughly in the next post.

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