A buddy of mine is building some chairs with steam bent arms. He is using
1/4 sawn kiln dried white oak and is having a heck of a time getting them to
bend. I have read conflicting opinions on whether or not kiln fried wood
will bend (he does not need much of a bend). Any of you have luck steam
bending kiln dried wood? Was there a trick to it? Maybe you steam longer
than the 1 hour per inch of thickness rule of themb? In my own experience I
have bent green oak and then years later bent wood from the same batch (I
guess by then it was air dried because I live in Utah where 20% rh is
considered muggy). The air dried behaved a little differently but not too
Thanks in advance,
Oak is probably more vulnerable to kiln degrade than other woods because of
the rays, which are natural places for splits to form and run.
Green rived is best, green sawn is all right. After a few cycles, even
air-dried gets some internal "set" to it.
Can your friend laminate the arms? On the quarter, it can be done almost
Cut the oak into 1/4" strips. The strips will bend much easier.
After removing the dried strips from the bending jig, glue them up and
put them back into the jig. The laminate will make the steam bent
arms all that much stronger. (This is how they make graceful and
strong banisters for curvy staircases.)
I have been bending kiln dried oak a lot lately for making various types of
basket handles. When I first began my "trials and tribulations" I had a heck
of a time. I was told by someone that I had to steam it an hour per 1/4 of
thickness. I was attempting to bend a piece of 3/4 x 1 oak into a 6" radius.
the thick side is the one being bent. I failed a number of times, then I
had a brain storm. I thought it was probably to dry to start with so I took
a few pieces of the cut stock, tied a rope around it and threw it in the
creek behind my house. It lived there for 6 days, ( the following Saturday).
I took it out of the creek, steamed it and put it in the forming jig. It
began taking the shape wonderfully, but then SNAP, some of the grain let
loose and it cracked. It didn't crack alot, but enough to make fire wood.
Then I had another brain storm ( with all the open space between my ears,
there seems to be alot of space for weather systems to move on through). I
figgered that the wood outside of the neutral axis had to stretch to
accommodate the longer circumference, after all the difference in
circumference from a 12" circle to a 14" circle is 6 9/32. So I bought some
.030 thk. stainless shim stock. I fastened two 1/2 thick blocks of stainless
to each end, with the distance between the blocks being the exact length of
my blanks. (You have to make sure they a fastened securely, I just used
machine screws the first time, but they didn't hold the blocks well enough.
I then drilled and reamed holes through the whole assembly, and pressed in
some 3/8 dia. dowel pins. They don't move now.) Then after I steamed the
blanks, I put it in the shim stock and bent it around my form. Eureka, no
cracks. So now I always support the outside of my blanks before I attempt to
bend them. I use .01 thk. shim stock for bending thinner pieces of wood. I
still let really dry wood soak in the crick for a few days before bending.
And a major problem I have is you that you must let the wood dry in the
bending form. If you take it out and set it some where, some of the bend
leaves it, and it will warp all cock-eyed. Although I have bent Cherry with
excellent results, without supporting the outer edge.
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