I just did a steam bending operation with 1/2" thick walnut. It was
successful,
but I was in such a connundrum over - should it be green? yes, only not. Can
it be kiln dried? No, yes? I heard, soak it in water first. So I tried that.
Now, the
begging question is, how much water did the kiln dried wood absorb, how long
should I wait to take it out of tension? I think it will spring back too much
if it's
too wet.
[email protected] (BUB 209) wrote in message news:<[email protected]>...
> I just did a steam bending operation with 1/2" thick walnut. It was
> successful,
> but I was in such a connundrum over - should it be green? yes, only not. Can
> it be kiln dried? No, yes? I heard, soak it in water first. So I tried that.
> Now, the
> begging question is, how much water did the kiln dried wood absorb, how long
> should I wait to take it out of tension? I think it will spring back too much
> if it's
> too wet.
2 weeks ago I attended the area Q MTCA meeting. There was a demo on
steam bending by the boat school in Wilmington NC (a 1 year course on
traditional boat building). According to the demo, wood needs to be in
the 15% or so moisture content prior to steaming. The Hot steam drys
out the wood, so if it is kiln dried to 5-6% you are more likely to
get failure. They soak the wood in water (actually sink it in the
river) prior to bending. They routinely bend timber up to 4 inches
thick for railings on boats.
tim
MTCA= midwest tool collectors association
BUB 209 wrote:
>>They routinely bend timber up to 4 inches
>>thick for railings on boats.
>
> Wow. One thing I've found is that bending
> takes a LOT of pressure. How much of
> a bend are they putting into that 4" wood?
> Is there a Bobcat involved in the process?
It's amazing how much force you can exert with a piece of rope and a stick
if you know how to do it.
--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
On 06 Aug 2004 02:15:39 GMT, [email protected] (BUB 209) wrote:
>One thing I've found is that bending
>takes a LOT of pressure.
Actually it takes a lot of force, and mustn't use too much pressure
(force divided by the area it's applied over) . For thick bends you
can easily require a force that's more than the crush strength (as a
pressure) of the wood, if you let the force be concentrated in too
small an area.
I've used hydraulic bottle jacks to bend thick timber (although not a
Bobcat !). It's quite easy to get the force you need, but spreading it
out with packing is hard - there's never enough fingers around when
you pull the stack out of the steamer.
The best way is usually to use truck tie-down straps about 3"-4" wide,
with wooden packing blocks loosely strapped to them. This keeps them
all together where you need them.
When I was a kid I always wanted a Bobcat....
--
Smert' spamionam
On 06 Aug 2004 12:01:31 GMT, [email protected] (BUB 209) wrote:
>>When I was a kid I always wanted a Bobcat....
>
>...The kind with wheels or the kind that
>eats small rodents?
Those skid-steer loaders that look like a bath-chair from
Thunderbirds. I used to see them at agricultural shows and I was just
taken with the idea of steering by sliding.
--
Smert' spamionam
If the wood was already below the fiber saturation point, your brief soak
added only unbound water.
You should be safe as soon as the piece feels the same temperature as other
wood in the room. A day or at most two.
It won't "spring" if it's wet, but relax slowly.
"BUB 209" <[email protected]> wrote in message
news:[email protected]...
> I just did a steam bending operation with 1/2" thick walnut. It was
> successful,
> but I was in such a connundrum over - should it be green? yes, only not.
Can
> it be kiln dried? No, yes? I heard, soak it in water first. So I tried
that.
> Now, the
> begging question is, how much water did the kiln dried wood absorb, how
long
> should I wait to take it out of tension? I think it will spring back too
much
> if it's
> too wet.
>