steam box/tube

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Spoke to a fellow commercial fisherman yesterday and we spoke about wooden slat catfish traps. I build mine square and he builds his round. He said he built a steam box for steaming the wood strips to bend in a circle. He said he would not build a steam box like his as it was not designed correct. He said that if he was to build another one or give me some suggestions as to how to build one. He said he would build  a tube long enough for the wood strips to lay in.  Approx 6 foot long tube.[strips of wood are a little over 5 feet] Angle it so you could pour water in the open end and put the lower end over a propane cooker or fire to make it steam. Make a lid and put some type of pressure release valve on it. The strips of oak wood are approx 3/16 thick. I'm sure several guys on here have built sometype of steam box or tube for whatever project. I'm looking for any tips or suggestions. Thanks RandyLincoln Power Mig 300 with PythonLincoln SquareWave Tig 255 Hypertherm Powermax 45 HH120 w/argon
Reply:I'm trying to remember exactly how a couple of the ones a friend of mine in college who did fine woodworking had  were built. I know they were an open systems. The big one had an old towel as the "door". It allowed you to easily open it up for loading/unloading of larger pieces, and kept pressures at nill. It had a couple of thru rods to allow the steam to easily circulate around the material. His small one was made of pipe attached to a "tea kettle" that sat on a burner under the bench. The pipe had a screw plug on the end as the door, but had 1/4" holes in the pipe to allow steam out. Again it had an interior "rack" to keep the material off the bottom and allow the steam to get to the material easily.He also used a hot pipe for bending, but IIRC the wood had to be thinner than what you are talking about..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Well, I searched and searched, but cannot find a picture of my current steam box.  I found one quicktime video, but I don't know how to upload it, I'll see if I can figure it out.  I built a small one when I had to replace some oak stems on a canoe restoration.  It's a about 8" x 8" x 48"  It's made from plywood, basically a box, with 1 x 1 cleats on the inside to fasten to. One end is sealed, the other end has a hinged door on it.  You do not need any kind of seal, there doesn't need to be any pressure in the system.  As mentioned, a towel makes a good door as well.  If a piece of wood sticks out the door (holding it open a little) I cover it with a towel.  I have a propane fired outdoor cooker.  It's heating a 5 gal metal gas can.  I put a 1 1/4" pipe flange and nipple on it.  There is a similar flange and nipple on the bottom of the box.  The two are connected with a section of exhaust hose.  Cook times are an hour per inch.  If you are going to use kiln dried wood, you'll want to soak it for several days.  I was bending green oak, it takes steam great, you want straight grain, no runout less than 1 inch in 12. Here'a picture of the stem I steamed and bent.  I'll see if I can get the video up.I can't upload the video... as far as a box for your application, a cleated plywood box would be the easiest to build and would stand up.  I would have the steam passing through the box with no resistance, rather than trying to boil water inside the box.    Another option is a section of PVC pipe, maybe 4", sealed on one end, plumbed to some type of kettle.  Get the box heated with good steam pouring out and then put the wood in.  3/16" should only need to be in the box about 15 minutes.   It's a good idea to make a test piece or two as well as extra pieces incase one breaks. Attached ImagesLast edited by villageboatshop; 01-26-2012 at 10:02 AM.
Reply:Here's a nice link for a plywood box unit like what Village says he has.http://www.dewalt.com/Blogs/post/200...d-Steamer.aspxhttp://www.ceolas.org/instruments/bo...in/MakeBox.htmhttp://www.instructables.com/id/How-...-bending-wood/Here's some picts and instructions for a PVC pipe unit.http://www.bayareawoodworkers.org/st.../steambox.htmlhttp://www.woodworkingplans.tv/do-it...a-wood-steamer.No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I use submersible grade plywood for steamer boxes water proof glue for joints/seams on the box, hinged door on one end for the access to wood, steam in the opposite end with a large diameter hose venting for the box is holes drilled on the bottom on door end of steam box. I have a big bucket with a lid that goes on the propane stove the lid is sealed with that high heat exhaust tape. You don't need or want high pressure.You can use any plywood if this is one time use, pvc pipe works also but can melt if you have this built correctly, steel is not optimal for steam box as it will suck your heat out of the steam.Before you build the box make + install slats/blocks  for the wood to sit on so the steam can surround the piece, leave spacing so water can make it to the vent holes otherwise you will have pooling and the wood wont be surrounded by steam as it will be sitting in water.Its best to use green wood for bending but you can bend even kiln dried wood but it helps to soak dried wood after you cut them to size.
Reply:I have seen a steam box made from ABS pipe, the chairmaker that showed it to me claimed it worked well. He used a metal 5 gallon paint can with a weighted lid for a boiler. A sink spud was clamped to the lid with a rubber hose  to connect the boiler to the steam tube.I offer three choices: Good, Fast, & Cheap. You may pick two.Hobart AC/DC StikMate LXHarbor Freight AD HoodHarbor Freight Industrial Chop SawDeVilbis 20 Gallon, 5 HP Compressor
Reply:Thanks alot guys.  I had thought this to be a welded up tube of some sort with whiskey still type steamer.  However i got to searching through google and found several boxes as you guys suggested. I do appreciate your help.  All of my wood is clear grade oak with zero knots. However it  is kilned dried.  I will follow your suggestions and get to building some catfish traps.Lincoln Power Mig 300 with PythonLincoln SquareWave Tig 255 Hypertherm Powermax 45 HH120 w/argon
Reply:Just soak the wood to saturate it  and you should have no problems  plan for some practice pieces and failed bends if you are bending dramatically. look at the photo below see the metal strap it is there to keep the grain of the wood from pulling apart and may be needed depending on your bends. 1 hour per 1" steam time for wood and don't steam too long as this can damage the wood too much and the wood structure will break down. If you are bending a lot of pieces just cycle some in after you pull out and bend some, bend first cycle new pieces in.Last edited by nikodell; 01-27-2012 at 07:26 AM.
Reply:Some people use the black sewer pipe.  ABS pipe can take quite a bit of heat and it is light and does not carry the heat away like metal.   The thicker the material the longer you have to soak the piece.  A one inch thickness needs a good hour or more.  Electric kettles are popular for a source since there are no open flames.