Democratic Armchair, Part 3: Steam Bending

This week was mainly taken up with shaping the various parts - legs, posts, stretchers and spindles - and setting them in my hot car to dry out a bit.  But I also managed to experiment with wood bending.  I had an extra stick of wood about the right size for a crest rail and I soaked if for 5 days.  The drawknife was used to get the staightest grain possible from it before taking it to 3/4" octagonal.  Just for laughs, I tried bending the soaked piece by hand and found that I could bend it about an inch over the 25" length.  Then I set it in the soaking bath again overnight.

I made a bending form from some scrap redwood.  This has a radius of approximately 16 1/2"

Here, I'm gluing on a cleat so I can hold the form in the vise

Here it is fixed in the vise.  Note the notches for clamps.
The curved rabbet is just over 3/4" deep and just under 3/4" wide.

When it came time to heat the wood, I took the piece out of the soaking tube and wrapped it in a kitchen towel.  I soaked the towel with water and then wrapped the whole thing in aluminum foil, sealing it as well as I could.  Then I poked a few small holes for pressure release and stuck it in the oven.

The experimental piece in the oven - just barely fits diagonally

I set the oven for 220ºF and let it cook or 2 hours.  The piece was 3/4" octagonal and in a steam box it would need less time.  But I figured with the towel insulating the piece it might take more time.  After 2 hours, I was worried that it wasn't enough, so I raised the temperature to 250ºF and gave it another hour.  I never did see any steam escaping from the holes I poked in the foil.

When I took it out of the oven and unwrapped it, there was a fair amount of steam.  The piece was easy to handle with leather gardening gloves.  Then I tried it on the form and to my surprise, it bent fairly easily.  It still took a little muscle, but it was easy to get it in the form and clamped up.

And here it is clamped to the form

I'll see tomorrow if it holds the bend or how much spring-back there is.

OK, it's tomorrow.

Here it is sitting on the form with clamps removed

There was a little springback, but I'm completely thrilled with the result ...

... even with these dents caused by the clamps

This was just an experimental piece.  If it turns out to be long enough, I might use it as the final crest rail.  This is partially because I mistakenly shaped the real crest rail into a spindle.  But for now, the bent rail is sitting on the dashboard of my car drying out.