can kiln dried wood be bent?

I need to create an arch. I want to bend a piece of wood, preferably something cheap into an arc. To get an idea of the radious I need, If I used an 8 foot length of 2x4 the depth of the arch would be about 10 in, if that makes any sense. It is a slight bend. I was wondering if this would work with a flimsy wood like spruce.
Could I build some kind of jig and bend it slowly, or soak it in something? I do have the ability to clamp it in place but not under too much stress.
Any replies appreciated.
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A 2x4 won't bend too easily, unless you can find a pre-bent one at the Borg.
The way I'd do it is to cut the 2x4 in thin strips, make a jig for the proper arch, have plenty of clamps available, and then glue the strips back together in the jig and clamp them until the glue sets. It's a lot of work, but you'll get what you want.
Jon E
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Hardwood is better for bending than softwood. Use Oak. White Oak, if this will be in an outdoors application.
Can you kerf cut the wood on the inside of the radius? Otherwise, you should cut it into strips no thicker than 1/4" and be prepared to bend and glue up a laminated arch.
Steam bending might work, but you would have to get something that could contain your 8' board while you steamed the heck out of it for two hours. You also need a bending strap on the outer radius. Steam bending is quite a chore ( I have some nice white oak firewood from failed attempts)
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Not sure exactly how this arch is being used(covered with drywall,left expsoed etc.) but you might be able to use a product called benderboard. Its a form of 'plywod' specifically made for bending. Rip a couple strips of that and bend and glue to a prebuilt form. You can also provide a better exposed surface(across the width) using 1/4 in ply with good surface. If a couple of layers are glued up it will be quite strong and hold shape v well.
BTW - benderboard(may go by other names depending on where you are) only bends in one direction and so is made in 2 forms;one to bend lengthwise and another to bend widthwise.
On Sat, 17 Jan 2004 21:28:23 GMT, "Jon Endres, PE"

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wrote:

What's it for ? Does it need to be weatherproof ? Does it need to be square timber ?

This is an extremely slight bend - a 10' radius You should be able to do this in a kiln-dried 2x4, provided you can hold it in situ afterwards.

Steam bending green timber is the best way to go, especially for small radius bending. However it's hard to do in thick sections, and it is helped by using green, straight-grained hardwood, split by riving rather than sawing.
Good timbers to use are ash (lovely stuff to bend, not very weatherproof), oak (a bear to bend, but good once you've done it) or willow (very well behaved and easy to bend, but you're probably going to be using roundwood)
For this shape, I'd bandsaw it from a pre-shaped piece of oak that grew with a curve near this shape - but that's because I have a yard full of such stuff and it's going for firewood otherwise.
One of your problems with any bending process is managing "springback" and for such a shallow bend in such thick timber, then that's a "spring" range that's almost as big as the curve. If this is rough work, then I'd try just bending the timber by hand and holding the ends in place.
If I really needed an accurate free-supporting arch like this, especially if I wanted a load of them, then I'd rip my stock to 1/2" strips and make a glulam structure, probably from Douglas Fir.
-- Do whales have krillfiles ?
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A 10-inch bend over an 8-foot span is not really severe. More than likely any wood: hard or soft could be bent to this radius. I don't think you have indicated the dimensions of the piece to be bent. If in fact it were a 2x4 it would require a lot of force to bend the wood even if it is steamed.
If however you are bending 3/4 in stock you shouldn't have a lot of trouble.
First I would figure a way to hold the wood in the bent position for an hour or so. Ideally you should "over bend" the piece a little as it will spring back some. This jig could be as simple as a 2x6 with a hold down on each end and a form to bend the wood over in the center (I.e. piece of 2x12 on edge at the center of the span?).
Second I would soak the wood in water overnight.
Then I would steam the wood for 15 min/quarter inch thickness. The easiest and quickest method for this might be a steam system I first saw in an article written by President Carter in Popular Mechanics. Essentially you take a length of stove pipe as long as your work piece, attach an elbow to the end and place the elbow into a pot of boiling water. Place the wood in the stovepipe and stop up the open end of the pipe with a rag. Tilt the assembly so condensed water runs back to the pot.
Remove the wood after the time period (wear gloves!! DAMHIKT) and QUICKLY put it in the form and secure it. Let it cool for an hour or so.
Remembering from college: Quarter sawn wood works best for steam bending, White oak is probably the best native species. Hardwoods out perform softwoods. I don't remember any research on kiln dried vs. air-dried. The radius that you are contemplating however should be ok for almost any species.
subject: can kiln dried wood be bent?

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On 18-Jan-2004, snipped-for-privacy@aol.com (Tchswoods) wrote:

Soaking dried wood doesn't add any benefit. You want to soak green wood to keep it from drying, but if it's dry, soaking it will do almost nothing.

It is considered that air-dried bends better than kiln-dried.
Mike
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On Sun, 18 Jan 2004 22:22:26 GMT, "Michael Daly"
For hardwood there's not all that much in it. It's possible that kiln-dried hardwood might even steam better than _some_ air-dried, because air-dried is often a lot older and age is also a problem in steaming.
For resinous softwoods, a hot kiln cycle is used to set the resin. If it has been kilned like this, then you can really forget steaming it.
My steamed timber is usually ash, but also oak, walnut and I'm about to do some lime. I try to keep my steamed timber dry and _steam_ it, not boil it. If you saturate the ends with water, it makes it hard to steam the center.
-- Die Gotterspammerung - Junkmail of the Gods
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I tried to bend a 2x4 this weekend and do not think this will work too well. lots of force is required for that but the 1x4 bent surprisingly easy. I think I might just laminate two of them together. I can bend them but now I have to find a way to hold them in a sprung state.
Will the wood eventually assume the bent shape, at least partially, or will I be under tension forever? I think I will use spruce because it is cheap and I have access to lots of it.
Also, If I glued the flat side of two 1x4s together in a bent state and clamped them together, wouldnt it stay bent after the glue is fully cured?
To e-mail me, remove all of the sevens from my address.
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wrote:

I think it's a square law on the thickness.

If you need this thing to be self-supporting and not needs the ends clamping, then I think glulam is a good way to do it. But I'd go for 1/2" strips.
Somewhere I have a big '50s handbook on glulam design (it was a popular large-scale architectural technique in those days). I'm sure there's a note in there saying that two lams and one glue line is a bad idea, as it's prone to twisting. -- Die Gotterspammerung - Junkmail of the Gods
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Don't know why it would twist, but it does put the maximum shear stress on the glue line.
Mike
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On Mon, 19 Jan 2004 20:02:42 GMT, "Michael Daly"

It's the taco problem. It's not that it wil ltwist on its own, just that if it does start to twist even slightly, it'll flip all the way.
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Make a jig out of a sheet of MDF or plywood, with dowels or other vertical support member to clamp the lamination to in the curve you want
John
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10 inch bow in an 8 ft length? Hell, you can probably find one already made at Home Depot.
--

Larry Wasserman Baltimore, Maryland
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Lawrence Wasserman wrote:

And Larry is the winner of today's MJG (Make Jo4hn Giggle) award. In case of duplicate prizes, we award ties. lol.     mahalo,     jo4hn
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I actually thought of that and when I went there there was a piece of wood that had about the same arc, but not centered. I guess over time I could find some.
On Mon, 19 Jan 2004 19:05:54 GMT, jo4hn

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