Hello All,
I have to build a few arbors, that will have a bend in them. I’ve never steamed wood before, so I was wondering what are the best woods for steaming that hold up to outdoor conditions. The diameter of the bend will be about three and a half feet. The customer has specified that she doesn’t want laminated lumber, so that is going to make things much tougher. Any imput that anyone has with regards to a steam chamber set up would be much appreciated as well.
Thanks,
Brian
Replies
Brian,
Do you mean a 3.5' diameter or radius?
I'm not sure what wood would would be good for outside that you could easily steam bend but I have some experience with a chamber.
Bent a 1 X 4 about 6' long and I used a metal drain leader, capped both ends and sued a wallpaper steamer for the steam. I think the rule of thumb is about an hour per inch of thickness.
Taunton Press has a very good book on steam bending.
ASK
There are others around here who will offer more expert advice on the best woods for your purpose. But you could consider white oak -- it stands up to the weather, and it steams well.
As for a steaming chamber, you could , of course, build some sort of lidded box. But a 4" PVC section of pipe will work just as well, as long as it is fully supported along its length (otherwise it will sag when heated). You need to drill a small hole (1/4") for drainage of the condensate, and buy two end caps -- one of which you can drill to accept whatever you are going to use to produce steam.
green lumber is best
air dried is second best
kiln dried may never bend, but ...
Hardwoods take steam better than softwoods.
Yeah, white oak. It bends fairly well, and it holds up well to the weather. Many of the woods you'd consider for outdoors don't bend as well -- most softwoods and mahogany.
In addition to learning about a steam box, you should also learn about a tension strap. There are good articles in old FWW, and a few books out there.
White oak is a good choice...popular for boatbuilding.
Best book I've seen is available at Woodcraft by Stevens and Taylor
http://shop.woodcraft.com/Woodcraft/product_family.asp?family%5Fid=3409&gift=False&mscssid=936BF2288337472BACBD903B17D3732F
Or you can ...www.bendywood.com
White oak bends well, survives the weather well, but will blacken if left exposed (ie no finish).
Contrary to expectations, you want the steam box to leak (that ensures the temp is maintained and that there is good flow thru the box. By leak, I don't mean from everywhere, but it certainly doesn't want to be overly tight. An inch/hour is the rule of thumb.
Greener is better. If air-dry, a good presoak will help. Watch the grain. The piece should have straight grain and be knot free. If there is grain runout that will promote splitting.
It's fun and smell great. Oh, and steam is like cubic inches and clamps, one can't have to much/many.
Brian,
I do extensive steam bending in the custom furniture that I design and create. If you do an advanced (Knots) search for steam bending under my Knots name - Jackie Chan, you will find a number of my posts that give step by step instructions on steam bending (e.g. set up, wood choice, bending technique, etc...)
If you have any specific questions, please feel free to ask!
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
I'm sorry that I didn't reply earlier, but life seems to have snuck up on me. I just wanted to thank everyone for their imput. It seems like white oak is ideal for what I'm doing as it bends well and holds up to weather conditions so that's what I'll be going with. Thanks to all for the thoughtful responses.
Brian
Brian,
Quarter sawn white oak with no grain run-out down its length is the optimum choice for bending. Remember the key is to steam the wood for one hour for every inch of (wood) thickness. If the wood is one inch thick, but a few inches wide the steaming time will have to be increased. (See my other reply to you in this post regarding my previous postings on step by step instructions on steam bending.)
If you have any questions, please feel free to ask!Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
I'm planning to steam bend a gentle arch for a canopy bed using maple boards measuring .75" x 2.75" x 6' 4". I had originally planned to rip the boards and then laminate after streaming but can a single board of this size be successfully bent without an excessive amount of spring back?
Doug
Doug,
yes and no. I did the exact same thing a few years ago. It took me two tries. The first time the form I used didn't have enough curve to account for the springback. If I remember correctly I build the form to account for the 3/4" thickness of the board as extra curve. I rebuilt the form with more curve and it worked fine. probably double the 3.4".
For steaming I used an aluminum drain leader I picked up at the local lumber yard and plugged the ends. and for the steam I rented a wallpaper steamer.
Hope this helps.
ASK
Doug,
Maple is not a wood that steam bends well. The fibers tend to crush in on themselves on the inside of the curve from the compression, and split on the outside of the curve due to over stretching. Maple can be successfully steam bent over gentle curves, but due to the 6'4" length you are working with, there will most definitely be adverse spring back.
The best approach in your situation, would be to resaw the maple into 1/8" x 2.75" x 6'6" (add some extra length to be trimmed to size as the last step), and clamp and glue them up around your bending form. This will create little to no spring back, and if you keep the resawn sections in the same sequence that they came from the solid board, the seams will disappear and will give you a curve that looks like a solid board was bent into that configuration.
I use Unibond 800 glue for most of my lamination curves. It comes in three shades to help match it to the wood - for Maple you will want the lightest color. You can order Unibond through Vacu Press in Maine http://www.vacupress.com/veneerglue.html
If you have any questions regarding the step by step procedure, or with any other questions, please feel free to ask!Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Dan,
Thanks for the advise. I was concerned that thinner laminations would distort the grain of the board. Using 1/8" strips, would you build in an any margin for springback?
Doug
Doug,
If you use the correct glue, and clamp it to a strong form, there won't be any spring back. The usual 20% over-bend used for steam bending (to accommodate spring back) doesn't apply in lamination bending.
When you glue up a lamination bend, clamping cauls need to be used over the length of the piece. They should be shaped to the same curve (the outer face) as the wood being bent. A good approach is to number each caul, and when gluing up the piece, start in the middle and work outwards (e.g. middle, the next to the left of middle and then to the right, etc...). This will evenly disperse the clamping pressure, as well as squeeze out any air gaps that might be between the layers.
As always, please send along any questions!
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Edited 7/27/2004 1:02 pm ET by Jackie Chan
Thanks Dan. Your time and helpful advise is always welcomed.
Doug
Do you ever use stainless steel bands in your bending jigs?
Nikki',
Yes I do - I use them when I build compression straps for steam bending. I also use galvanized sheet metal straps. They're less expensive, and readily available. Depending on the size of what you're bending, you can find galvanized steel strapping in a number of different widths.
I add wood handles on the compression straps that I build, for added leverage, and greater control over the stock being bent. The handles are also an attachment point when I use wire cable or rope with a come-along or ratchet crank to pull major bends around their form.Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Do you have any suggestions on the best place to buy either stainless or galvanized bands that could be used for compression straps?
Thanks.
Nikki',
The best place to start would be the yellow pages. Look up Sheet Metal and you'll find everything from suppliers to fabricators. Most sheet metal suppliers will have both galvanized and stainless steel on hand.
When you are making a compression strap, you want it to be smooth and distortion free. This means that the metal should not be cut with the standard metal sheers or snips - it should be double cut, which means cutting the material from both sides simultaneously. A double cut edge is square and distortion free. Most suppliers can cut a sheet of metal to the width you want. I'll buy an 8' sheet of metal and have my supplier cut it to width in the sizes I use the most. He could easily cut it to length, but I leave it at 8', and will cut it myself depending on the strap design I'll be using. It doesn't matter how the ends of the strap are cut, as they're mounted to wooden lever/handles and never touch the bending stock.
Another place to look is HVAC suppliers, they use galvanized sheet metal for duct work.
When buying metal, it is very important to purchase the correct gauge (thickness). The strap is put under tremendous loads, and if the metal isn't up to the task, you'll find it quickly stretching and distorting under load, and potentially ruining the bend. I usually use 14 gauge steel which is 0.0785" (5/64"), and 16 gauge steel which is 0.0635" (a little more than 1/16").
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Edited 7/27/2004 11:47 pm ET by Jackie Chan
Dan,
I Googled for artickles on compression straps with no success, at least as it related to wood. Do you have a recommended source/
Doug
Doug,
This is a link to a previous post that I wrote, giving detailed instructions on building a compression strap. As well as additional information on the bending process.
If you have any questions, please feel free to ask!
http://forums.taunton.com/tp-knots/messages?msg=6875.6
http://forums.taunton.com/tp-knots/messages?msg=6875.6
http://forums.taunton.com/tp-knots/messages?msg=10529.2
http://forums.taunton.com/tp-knots/messages?msg=10529.6Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Dan,
Once more, thanks. That clarified the question for me.
Doug
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