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To bend wood, you need steam. The typical way to do this is to build a steam box that fits your part-to-be-bent inside. But there are three drawbacks to this method: The box must be sized to fit your piece; when you remove your piece from the box and transport it to your mold, it begins to cool, losing elasticity; and when not in use, the box takes up precious shop space.
Louis Sauzedde, the wood expert and master shipwright we looked at earlier, uses a different wood-steaming method that solves all three of those issues. Sauzedde doesn't build a box at all: Instead he steams the pieces inside a plastic bag.
In a word, it's brilliant. He's steaming the pieces directly in place, and the tighter confines of the bag mean more steam is concentrated closer to the wood, rather than taking up all of the the dead space in a steam box. When he's done there's no box to store. And the plastic can be cut to length to accommodate the piece.
Here's a clip of Sauzedde steaming a different piece, this one right at a mold:
For you furniture designer/builders who have been looking for an economical way to steam, particularly in a small shop, this seems ideal. If you try it, write in and let us know how it works out!
I’m a lapsed industrial designer. I was born in NYC and figured I’d die there, but a few years ago I abandoned New York to live on a farm in the countryside with my wife. We have six dogs.
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A Better Way to Steam Wood for Bending: Use a Plastic Bag!
This may be a good method for the type of steaming shown, where very thick pieces of wood need to have their lignin activated (thickness of wood dictates length of time to saturate heat to depth of wood), but thinner woods would not fair as well due to teh heavy moisture saturation of the wood fibers leading to grain failure.
I am currently building a 13' sailing dinghy and used Lou Sauzedda's poly bag technique for bending the stringers, some of which are 2"X3/4"X12' pine! His system is flawless. I got the sleeves from US plastic. The product is called layflat and comes in 6 mil X 1000 roles As Lou did, I simple put the stringer in the bag filled an old oil can with water connected it to the bag with a hose and wire ties, put the can on a propane burner and let nature do her thing. After an hour of steaming, the stringers were like noodles and bent on to the stations with no problem. I don't believe I could have gotten the on dry. Thanks Lou!!
How did you make the bag, just tape it or did you buy one already sealed. Can you make one with a freezer bad machine, just so long as it is sealed nice to see a vidio on how it is made thanks
A perfect source of bags are the replacement liners for baby nappy/diaper bins. Search online for liner bags compatible with Tommee Tippee Sangenic. The non-branded compatible ones can be bought in 200, 400 and 600 metre rolls. Try amazon or ebay.
Nick Polanksy (Artist in Resident) at the Autodesk Pier 9 Workshop just posted an instructable on his kerf cutting project. He built a steam bag system for steaming large and long pieces and it worked perfectly!
Thanks for another great post Rain. For those who are wondering the plastic used in the video is 6 mil polyethylene melted together (Uline.com sells it in tube form).