A Steam Box For Not A Lot

If you have ever marveled at the complex wooden curves used by shipbuilders or some furniture makers, then you have probably at some point hankered after a steam box. This is as its name suggests, a chamber in which a piece of wood is steamed until it becomes flexible, at which point it can be pressed into a new shape that it will retain once cooled. The ever-resourceful [Xyla Foxlin] shows us how to make a steam box using easy-to-find parts, as can be seen in the video below the break.

The steam supply comes from a commercial steam boiler of the type used by decorators for wallpaper stripping, and the steam box itself is made from a length of PVC pipe. Inside the pipe are a series of aluminium dowels that form a rack upon which the wood sits away from any condensation, and the whole things sits at a slant with the steam inlet and a condensation drain at the bottom end.

In use, a piece of wood is loaded into the tube and steamed, before being bent using a set of forms in a vice.  The process looks straightforward enough that even we could give it a go, so we’re sure Hackaday readers will find it interesting.

We think this may be the first steam box we’ve brought you, but it’s not the first time we’ve discussed bending wood.

Thanks [Abe Tusk] for the tip.

21 thoughts on “A Steam Box For Not A Lot

  1. Personally wouldn’t use PVC piping for a project involving steam. A lot of off the shelf PVC melts at rather low temperature.

    I would go for a piece of ventilation duct made from galvanized steel.
    Since it is easy to source in whatever dimensions one needs and it doesn’t risk melting nor softening from steam. Duct work is also fairly good at containing air pressure so steam leaks wouldn’t be a major worry, all though an outer heat shield should be considered in case someone touches it during operation.

    Some HVAC companies wouldn’t bat an eye if asked to throw together a wood steamer. It is a length of insulated duct (typical in a lot of industrial applications), an end cap and a lid (used for cleaning ducts), a set of legs (in mechanical floors and on roofs ducts are often standing on the floor), a steam inlet (common for humidifying air in larger buildings) and a drain (water sometimes collects in ducts). Rather common parts that are all used in HVAC applications already.

    1. I made a somewhat similar if less nicely designed PVC steambox, and yeah, it sags a LOT in use. I ended up making a v shaped trough to support it, and had to bolt the end cap on because it too would sag and basically fall off, and because of the sag of the overall tube, I couldn’t get it back on.
      But it did work, for cheap.
      I set mine up to return condensate to the boiler (just a teapot on a hotplate) so I didn’t have to refill and possibly kill the steaming.
      One thing I learned from watching Xyla’s youtube stuff on steam-bending was to flatly ignore the traditional steaming times and just let it go as long as possible, like 5x the steam time that the books say. That was a huge help in getting a very fussy process a little less annoying.
      Another thing I learned just from playing around is that you can use 3d printed bending forms if you wrap a sheet of leather over them to protect them from the heat of the wood.

  2. The classic iteration of this for bending your canoe ribs, was a iron pipe downspout, capped one end, with a quart or two of water in it, one end in a fire (outdoors) … typically at more of an angle. Modern imitations of that, might use aluminum sheet formed downspout, one end mashed and rolled to seal.

    1. HaD bloggers are famous for their low signal-to-noise ratio, and rather high distortion factor.

      But if one vents about those flaws to much, their ed-in-chief goes Larsen in your mailbox about harassment, poor creatures …

  3. I saw this steam box in use in her recent video and I have doubts about its efficacy. Real steam boxes have steam at hundreds of degrees, I doubt that a garment steamer is going to provide the very high temperature steam that is ideal for wood. She had to steam the wood for over 24 hrs and it still fractured because it wasn’t fully wetted, that speaks to a lack of temperature and penetration of the steam. The Engels Coach Shop YT channel has a number of videos of steam bending and his rig can do big wagon stays in a reasonable amount of time.

    1. There is a show that used to be on PBS (Public Broadcast System) in the USA that was called The Woodwright Shop. The host of the program is a man named Roy Underhill. He used only turn of the century tools on his program and made some of the most amazing furniture and the like I have ever seen. Because of this program I was encouraged to buy tools like a brace and bits, spokeshave, and drawknife. In several of the programs he uses an iron tea kettle on a woodburning stove and heats wood to a bendable state in 10-15 minutes. His steamer box is made of wood and about 6 FT or 2 meters long. I wonder if the wood construction makes a difference in that wood will hold heat and moisture whereas the abs would lose heat to the atmosphere at a much higher rate. I also wonder if you built one out of abs but with another outer tube insulated from the inner tube would work better. (Think thermos or insulated vessel.)

      1. “The host of the program is a man named Roy Underhill”
        Lovingly referred by galoots* as “Saint Roy”

        *galoot: person who preferably uses human powered tools for woodworking, and vehemently denies obtaining such tools as “collecting”.
        See: Disstonian Institute and oldtools forum

        1. I could be a semi-galoot, mostly just use power for ripping, and for stuff that’s an offense against nature, like particle board. Then I will do a lot of softwood drilling with brace or “egg whisk”, use spiral ratchet driver etc.

      2. FWIW in most of her previous videos Xyla has used a wooden steam bending box. But they do leak at joints and one nice thinga bout ABS is it only has the end cap joints.

  4. My best steam box is no box. I use 6 mils polyethylene that I hot seal with a small sealing machine to make a bag, that I keep almost sealed with a small spring clamp. I make a couple small holes with a pencil for dripping excess water. The bag fills with vapour till the excess get out of the small leaks at openings. You can even keep the bag on while bending while being carefull of course. I use the earlex steam generator. I checked with an infrared thermometer an it gets to 99-100 degree Celsius easily

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