I’m wondering if it is possible to steam bend wood twice. In other words I’d like to slightly bend 5/4 black walnut, work it, then resteam and bend to final shape.
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Hello davidg
I haven't done a lot of steam bending ,but could you do the working first then steam and clamp into former to take both shapes in one go. Much less distressing to the timber and only one heating session.
regards (make a cuppa for me while the waters hot ) Teabag.
"I'd like to slightly bend 5/4 black walnut, work it, then resteam and bend to final shape."
David,
May I ask what you're building, and why you're interested in using the double-steaming method you described? Is there a reason you cannot complete your project with only one steaming session?
-Jazzdogg-
Whether you think you can, or you think you can't, you're right.
Dave,
I do extensive steam bending in the custom furniture that I design and fabricate. The short answer is "no", you shouldn't re-steam wood after it has already been steamed and bent. If a piece of wood spends too much time in the steam box, it will actually dry out, becoming brittle and easily fractured.
The wood needs to be steamed for the correct amount of time, (rule of thumb is one hour for every inch of wood thickness, other variables will change the amount of time) and bent as quickly as possible - move from the steam box to the bending form quickly, bend more slowly so the wood can take to the bend. This will reduce the amount of spring back once the piece is removed from the bending form. Reheating/steaming the wood will cause it to dry out and fail in the bend. It is possible to do multidirectional bends, but this should be done all in one step.
Walnut is a poor bending wood. This wood will fail due to the compression and tension of the bend. Meaning, it will crush on the inside of the bend, and split and tear apart on the outside of the bend.
If you have any questions, please feel free to ask!
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Dan,
Do you steam-bend every time you need a curved surface or do you slice laminations for some projects? What determines which process you use?
Regards,Bill Arnold - Custom Woodcrafting
Food for Thought: The Ark was built by amateurs; the Titanic by professionals.
"Do you steam-bend every time you need a curved surface or do you slice laminations for some projects? What determines which process you use?"
Bill,
In my work I utilize steam bending, laminate bending, as well as coopering and kerf bending. Steam bending works best on a handful of straight grained hardwoods, and only gives marginal to poor results on others. The best woods for steam bending are quartersawn white oak, birch, beech, hickory, and ash.
I'll steam bend when the wood is a good candidate, as well as when I want continuous grain, uninterrupted by possible laminate lines. That being said, if I want to bend an especially thick piece of wood, of a species that normally steams well, I will resaw it down to the appropriate thickness and lamination bend it. When considering steam bending, one must contend with spring back as the piece cools. It is also is more prone to seasonal movement. (There are ways to minimize and counteract these issues.)
Lamination bending works well on all species of wood. The only thing to contend with is the possiblity of seeing the layers after the veneer glue is applied and hardens. I use Unibond 800, which comes in two colors - one for light woods (maple, etc...), and dark woods (cherry, etc...). If the wood is kept in the order that it was resawn in, and the correct glue color is used, the laminate lines are almost invisible. (See the enclosed pic. of one of my recently finished cradle prototypes - it is solid maple that utilizes laminate bending throughout the piece.) This type of bending has very little to no spring back, or seasonal movement.
What determines which technique I use are: the wood's bending characteristics, the size and thickness of the wood to be bent, the time it would take to bend the piece (steam bending takes an hour or more for each inch of wood thickness.), and lastly what the final visual result will be.
If you have any questions, please feel free to ask!
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Edited 10/25/2004 6:59 pm ET by Jackie Chan
Edited 10/25/2004 11:13 pm ET by Jackie Chan
jackie
thanks for the response. i am going to use a different wood. initially i was thinking of a dark wood and have read a couple of different opinions of walnut, but the overall consensus agrees that walnut isnt very reliable for bending. so now im wondering if wood that has some spalting in it can be considered reliable and should i cut the spalting out? my local lumber dealer has some beech which i have read is a good wood to bend.
David,
For what it's worth, I built a headboard that is primarily cherry, but has a walnut top cap to the crest rail. I never considered bending it, but I did take a piece of black walnut, resawed it into 1/8" strips and laminated it directly onto the crest rail. By carefully indexing the walnut when cut and also when gluing it onto the crest rail, the grain matched nicely. Before finishing, the laminations were barely visible and virtually disappeared when finished. Finish was BLO/MS topped with polyurethane. I attached two photos; a closeup of the crest rail and an overall shot of the bed.
Regards,Bill Arnold - Custom Woodcrafting
Food for Thought: The Ark was built by amateurs; the Titanic by professionals.
David,
Beech is one of the better woods for steam bending. Any number of things can cause a bend to fail - grain run out (grain that runs out of parallel to the rest), knots, etc...
You may run into trouble with the spalting. If at all possible, remove the spalted areas - you are aiming for straight grained, clear (no natural defects) wood.
Do an advanced search under my Knots name, Jackie Chan, and type in steam bending. I've posted step by step steam bending instructions that should prove helpful.
If you have any questions, please feel free to ask!Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Get Stevens book Wood Bending Handbook from Woodcraft for $14.99. It list properties and radiuses you can bend various species to. Great book for the money.
David,
Wood is funny and until you try, you'll never know for sure. I'm building a bed and for the top rails for the head and foot boards I ripped 2 - 1" x 3.5" x 40" piece of birds eye maple into 4 equal slices each, steam bent them and then laminated using Unibond 800. Granted, the bend is not extreme but the consensus was that the birds would split out due to the inherent weakness at the "eyes". It didn't and the curved head and foot boards are coming out nicely. After reading Bill's post I'm wondering if I could have bent the piece without quartering them first.
I experimented on one piece first and then went from there. Up to that point I had only done laminations. Bottom line, expert advise, particular from someone as experienced as Dan, is a generous gift and your personal experiences are the foundation of your craftsmanship.
Davidg,
The top rail on a bed I was making a number of years ago was a 1" X 3" piece of maple about 66" long. It was my first bending attempt. Built the form, steamed the wood, clamped it to the form and let it dry. The springback was more than I had anticipated. A week later I rebuilt the form, resteamed the piece and clamped it to the form. The second time it worked without any problem or trouble.
ASK
Bending wood twice will be extremely difficult unless you are able to do the second bend with the wood clamped in a fixture. If you re-steam your first bend, you will lose most if not all of the bend. Also, I've found that re-steamed wood is much more brittle. This is witnessed by the large box of kindling I've accumulated while making rockers.
You would probably be better off by building a very stout compound fixture and working very quickly. (If you're not into your second bend in 30 seconds, you're probably not going to make it.) You will also benefit from using an extra-long piece of stock. For instance, if your finished piece is to be 36" long, 60" of stock will be most helpful when you're bending that second curve.
Good luck. My e-mail address is [email protected]
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