# Wood steaming jigs and boxes - two questions.



## snav (Jan 24, 2010)

Question 1: Is there a maximum size that's recommended for a steam box? With my plans to bend wood for some cabinet doorframes I don't see myself being able to make use of a pvc sized setup - or even a larger box setup that others have made.

But these medium and small sized setups are all I've ever seen when researching this project.

So does this mean I'm approaching an idea that shouldn't be done? Or is it just that my idea is doable but not quite the norm?

Question 2: Is there a reason why metal is not used for a steam-box? Is there a risk of scortching the wood if it's resting on a metal rack?


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## woodnthings (Jan 24, 2009)

*Go to You Tube*

Plenty of stuff there:





http://www.youtube.com/watch?NR=1&v=jCncI-8NdP4


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## cabinetman (Jul 5, 2007)

snav said:


> Question 1: Is there a maximum size that's recommended for a steam box? With my plans to bend wood for some cabinet doorframes I don't see myself being able to make use of a pvc sized setup - or even a larger box setup that others have made.
> 
> But these medium and small sized setups are all I've ever seen when researching this project.
> 
> So does this mean I'm approaching an idea that shouldn't be done? Or is it just that my idea is doable but not quite the norm?


The size of the box would matter if the input of steam wasn't adequate. The closer to the size of the subject piece the faster and more efficiently it will get pliable. PVC works well, as you can get fittings and pipe diameters of various sizes. If you need something larger or especially shaped, make it out of plywood. 



snav said:


> Question 2: Is there a reason why metal is not used for a steam-box? Is there a risk of scortching the wood if it's resting on a metal rack?


The wood can rest on any support. Metal containers would be more difficult to configure for a steam box, as for inlet/venting, opening/closing.












 







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## Hammer1 (Aug 1, 2010)

People that build boats use massive steam boxes. You can build whatever size you need but you have to understand the principles in steam bending. You will get the best results, with certain species and with lumber that is riven and even better with green riven. You won't find riven lumber anywhere, you have to make your own from a log or cant. If you use ordinary KD sawed lumber, you don't have continuous running grain like you do with lumber that is split rather than sawed. This can mean the pieces will break or not bend as you want them to. If you try to steam something like a 1x8, it will usually belly across the width and be useless. With sawed lumber, you can expect a high failure rate. 

In order to steam wood, you need to make lots of very hot, billowy steam. This stuff is dangerous, it can burn you badly in a second. The steam needs to be consistent and you don't want to run out of water during the process. A wallpaper steamer might work for a very small box doing small pieces but it won't be adequate for a large box. Steam condensates as it cools forming water. You don't want your pieces laying in condensation or contacting iron or you may stain the wood. A hour per inch is a reasonable estimate but only if you have enough hot steam.

Folks often insulate their steam boxes to minimize cooling. You should have a way for the condensation to get out, usually running back into the steam vessel. Grids are built in the boxes to keep your lumber up and off the wet floor of the box. The box can get hot and when you open the door, the steam can burn you, so wear gloves and keep your face away. While PVC pipe boxes are easy to make, they can distort or even melt during a long session. 

I use a 4" PVC pipe and it's just about right for what I've had to steam. I have an aluminum soffit vent inside for a grid. I use a 5Gal. can on an old gas burner. It's connected to the box with a radiator hose. I have a couple electric tea pots that I can pre-boil replacement water with and a spout on the can where I can add the hot water. 5Gal. of water can boil off fairly quickly. 

You only have seconds to work once the piece comes out of the box. You have to have your forms set up and get the pieces in them pronto. Leave them in the forms overnight or longer to completely dry. Steaming is a lot of fun but gets more difficult with larger pieces. Small moldings, 1/4" x 1/2" are easier than 3/4" x 2". With tighter radii, you may need a compression strap. If you want to bend a 4x4, you would be better off to cut it into thin strips and laminate it in a form, no steam.


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## snav (Jan 24, 2010)

Thanks for all the input - I'll read up more on the specifics of steaming per boat building since that sounds like it'll be more along the lines of the size of wood/project I might be working with.

My plan - if I go through with it - will center around using my old smoker-pit rack as a support for my board in a ply box - with a hatch type cavity that opens - the entire rig would slide out the side which cuts down on the cooling time. . .if I don't go "big" I could plan to use my old smoker in it's entirety - with some insulation and adjustments made. 

Another plan I piddled with on paper was crafting a rig that can bend while the wood is in the box through a series of gears, bars and external pulleys.

But these ideas are complicated - I might be better off keeping it simple: bending and assembling smaller pieces - this would make use of a smaller rig and the wood will be more likely to give.


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## woodnthings (Jan 24, 2009)

*some wood can bend without steam...*






What wood are you intending to use?


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## snav (Jan 24, 2010)

woodnthings said:


> Extreme Wood Bending 6" thick White Oak - YouTube
> 
> What wood are you intending to use?


Good video - thanks.

The wood choice is between a few woods. My cabinets are birch, pine, oak but I can add a 4th species in - or stick with those. I've read that pine is ill-advised and some others come with some issues like buckling and so on which can complicate the process. 

On my land I have some aspen, elm, crabapple and spruce that need to be removed because they're diseased or suffer from wetrot . . . but aspen and crabapple - you know, no one uses these woods for anything so there's little information about them out there (well, in my reading so far anyway).

I'm just trying to gather all my information before making any decisions - if I start going towards this part of the project it's going to take a lot of time and some extra money to achieve and that's not something I have in abundant quantity.


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## FiveOneSix (Sep 26, 2009)

*let's go to the video tape!...*

im still at work so i havent watched the vids yet...

i have a question though...i have heard about not bending sawed lumber...however, i want to bend a 50" 1X7 or 2X7 board. will a piece that size still be very likely to break when bent? im thinking ash, purpleheart, maple or walnut.

any thoughts?
THANKS!!!


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## FiveOneSix (Sep 26, 2009)

*trickery...*

HOW DID THAT OAK NOT BREAK?


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## snav (Jan 24, 2010)

Crazy, huh - I read up on the compression method he uses, interesting stuff.



> It has just been subjected to carefully controlled, but intense, longitudinal thermo-mechanical compression (approximately 100,000 lbs). The hardwood has been engineered to be extremely flexible (as long as it is moist). It is shipped to you as planks wrapped in plastic to maintain it's moisture for long periods of time (months to years) so that it can be kept on hand for current and future projects.


Some of the pieces shown on his site are insane - real works of art. http://extremewoodbending.com/discovery.html

So I imagine then that the wood is larger than it's final size before compression - like a roll of insulation. Being compressed - it allows for an almost elastic response in the wood lignin (etc).


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## cornskier (Oct 19, 2010)

*Steam box*

I worked in a boatyard for several years and the steam box the wood workers used was about 18x18 inches and 20 feet long. Fed by one large boiler. My son had to bend some teak rail and we built a box about 12x12 inches and 8 feet long, powered by my wife's steam machine for clothes. Both work for bending depending on what you need to bend and the steam supply. My home unit was a single use project in a hurry but it worked. If you are doing a lot of bending, I suggest cedar ship lap for the box. It can be purchased in 12 foot lengths and easily over laps to several feet if you need that big. Typical width is 12" the tighter the seams the higher the temperature and the faster the bending. Put a pop off vent at the top of the box, just a piece of pipe with a lid that will hold most of the steam but not let the pressure get too high. Have fun. Wear leather gloves when working the material and have a form ready when the wood gets soft.


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