Replies

1. 
   BarryR | Sep 27, 2004 07:12pm | #1

   Check Lee Valley's catalog for a pic of a steam box to be used with their electric kettle & steam tube.  It's just a plywood box - looks like it's made with nailed but joints.

1. 
   cherryjohn | Oct 10, 2004 04:27pm | #16

   I ade mine out of galvenized stove pipe and gal. T and 3 end caps.  One end cap was fitted with a steel nipple anout 6" long to accept a piece of plastic hose that joins a 5 Gal steel gas can.  I assembled the 6" pipe sections with the T in the middle and put and end cap with the nipple to the free end of the T.  The whole thing was mounted to a section of 2X8 with pipe straps.  When I bend wood I take it down from the shelf and set it up on a gas burner and fill the gas can with anout 2 gal of water.maybe less.  I use it all the time as my hobby ios maling windsor chairs and it has been in use fir at least 3 years.  The whold thing including the gas burner cost $100

1. 
   BarryR | Oct 10, 2004 08:01pm | #17

   Using a gas can as a boiler is a great idea!

2. 
   mlbfreestyle | Sep 27, 2004 07:19pm | #2

   I made one several years ago and it has worked well.  Nothing more than a cheap plywood box; approx. 12" wide, 8" high, 48" long.  Open on both ends.  I put a few cleats across the bottom at 12" intervals to keep the stock off the bottom.  I made a simple "plug" type cover for each end to close it off.  One end has a vent hole to allow hot air to move through and out.  The other end has a PVC hose barb in it to attach a clear flexible tube (something you can buy at the orange box).

   I fire it up with a "goodwill" store kettle with lid on an old hotplate.  I put a PVC hose barb in the lid to match the one in the box.

   Put the box across some saw horses; set the kettle and hotplate below this level; add water and heat!

3. 
   hammer1 | Sep 28, 2004 12:51am | #3

   Schedule 40 PVC pipe, old BBQ propane side burner, old metal can, length of radiator hose.

   I've found that you need to generate some good long steady steam. Wallpaper steamers and tea kettles don't have the ability to produce enough. I use an electric kettle to heat up replacement water. I have a length of aluminum soffit vent in the pipe to elevate the wood from getting soaked by condensation. A 1/4" hole in the end of the pipe reduces pressure to keep the end caps from blowing off. The old metal can was the hardest to find. I wanted one with two holes so I could add water when needed. No gas fumes, eh!

   The PVC crowns up when it gets hot. Doesn't hurt anything, goes back to normal when cool. Wear gloves and watch your face when you open the cap. I'm not afraid to let my stock steam for a good long time. Start bending immediately out of the box. Use a sandwich form for repetitive work.

   Beat it to fit / Paint it to match

   
1. 
   jackplane | Sep 28, 2004 03:47pm | #7

   Thanks Hammer for your photo and plan. I guess you didn't use a pressure relief valve? I'd like to use one with PVC, for safety reasons. Do you know the psi setting for this?

   Thanks to everyone for their interesting ideas!

1. 
   EdHarrow | Sep 28, 2004 05:27pm | #8

   You shouldn't need a pressure relief valve as a steam box should leak a bit (maybe even more than a bit).  You want nice, fresh hot steam filling the box, and for that to happen the old stuff has to be able to get out.  On the other hand, too much flow won't get stuff sufficiently hot.

   Most boxes with which I've been affiliated are made of plywood, and have sticks across them at various heights (like oven racks) so the victims can be placed upon the racks, and the steam afforded good access to them.  Additionally, if steaming a bunch of wood, one can lay them upon the racks at different times, and eventually get a rolling production of supple wood.  The heat sources were typically big propane burners, like those sold for outdoor cooking pots, and often the tank was a metal gasoline can (allegedly one never used for gasoline, LOL).  I also have planes for a small, electrical steam generator that supposedly works like a tankless, on demand, water heater. 

   Fresh-steamed oak.  Yum yum.

1. 
   jackplane | Sep 28, 2004 08:39pm | #9

   Sounds good, but why do you need fresh steam constantly replacing the old?

   Seems to me a large PVC tube with an adjustable valve would reduce the need for water and maintenance...

1. 
   jackiechan | Sep 29, 2004 05:17am | #10

   Jack',

   When steam bending, it is live steam that is generating the heat necessary to relax the lignin.  The white steam that you see rising from boiling water is not Live steam.  This steam is actually the live steam cooling and recondensing.  

   Live steam is almost invisible, and can be seen as heat vapors just off the surface of the boiling water - the white steam will be just above that.

   The goal of steam bending is to make the wood fibers and connective material pliable - not wet.  It is possible to over steam a piece of wood and actually cause it to dry out to the point that it will crack under the bending loads. 

   To answer your question, the (live) steam needs to keep circulating so that the wood is consistently heated at the right temperature for the appropriate amount of time.  The recondensing white steam cannot do this.  A steam box should never be under pressure!  A container pressurized by heat and steam over a period of time will tend to want to release itself in a particularly nasty and explosive way!

   I do extensive steam bending in the custom furniture that I design and build.  If you have any questions, please feel free to ask! 

    

   Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.

   Edited 9/28/2004 10:22 pm ET by Jackie Chan

2. 
   EdHarrow | Sep 29, 2004 05:33pm | #12

   What Dan said - tho I did once attempt to convince a certain party that a tight, tubular steam box, with a potato stuck in the end of it, might just be the perfect thing ...  ;-)

   PS: The right amount of time - rule of thumb is one hour of steam/inch of wood (but can be considerably less if the wood is moist)

   Edited 9/29/2004 10:36 am ET by EdHarrow

3. 
   jackiechan | Sep 29, 2004 07:50pm | #14

   Ed,

   I think you meant to send your reply to Jackplane.  ... but a potato cannon sounds intriguing!Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.

2. 
   hammer1 | Sep 29, 2004 06:54am | #11

   Jackplane, I didn't feel there was a need for a valve. Steam as you know, can cause severe burns so I did not want to build too much pressure in this pipe. I actually drilled a 3/4" hole under the blue towel on top of the pipe. This hole was too big so I closed it down to about a 1/4" which seemed just right. There are some relief valves that are adjustable down to 15 PSI and I'm sure one could be installed in place of the hole. They aren't very expensive, $20 +-. With such a large, 2 1/2" hose , I think excess pressure would be forced back into the boiler. Although the schedule 40 is rated at 220 PSI, I don't think that is steam pressure and that old can would scare me. They are hard to find. I know, don't ask, that an old motorcycle gas tank can be ruined with less than 10 PSI. I would question this boxes ability to carry much pressure so I opted for additional steam time. Sorry I don't have a more technical answer, just a "seat of the pants" feel. I have run the box all day for weeks and it has done what I needed it to do.

   Beat it to fit / Paint it to match

4. 
   Patto | Sep 28, 2004 01:02am | #4

   Old army trunk with a couple of bricks in the bottom, about 2" of water in the bottom, wood on top of the bricks, whole lot on top of the BBQ. Water inside kept it sufficiently cool that the paint was unaffected except right on the bottom. Weight of the lid acts as a pressure valve with the rubber seals. Worked a treat.

   Dave

5. 
   jazzdogg | Sep 28, 2004 06:15am | #5

   Here's a snapshot of the rig a friend of mine uses to steam chair legs for bending.

   -Jazzdogg-

   Whether you think you can, or you think you can't, you're right.

   
6. 
   joinerswork | Sep 28, 2004 03:30pm | #6

   Jackplane,

   For occasional bending, I've had success with galvanized 6" stovepipe. Assemble an appropriate length for your project. Cut a plug out of wood for the inlet end, with appropriate hole for the steam tube.  The plug for the outlet should be easily removeable, to place/remove bending parts, with a drain hole for condensate to leave.  Support the pipe with this end slightly lower for drainage.  The pieces to be bent may be supported with blocks of wood.  It helps to drape a piece of fiberglas insulation over the pipe to keep temps up... Bent everything from ladderback chair slats (15"), to windsor chair repair parts, to snowshoes, to stripper canoe gunwales (15') with this setup.

   We even bent snowshoe frames once at a Boy Scout Klondike Derby.  Cooked the ash pieces in a leftover "Raingutter Regatta" race course, over  several Coleman campstoves.  It worked fairly well, considering we boiled rather than steamed the wood, and it was about 15-20 degrees F at the time.  We had to work faster than normal to get the wood in the forms...

   Cheers,

   Ray

7. 
   DougF | Sep 29, 2004 05:52pm | #13

   Jackplane,

   About a month ago I build a steam bending system using 4" pvc, radiator hose, a five gallon gas can(a new can!) and a propane fed deep fryer stand.  The most expensive part was the can.  I finally had to pay $40 for a 5 gallon "safety" can that only had one spout.  I brazed on a second 1" copper spout.  I drilled two 3/16" weep holes at the end of the pipe and set the pipe on an angle to drain the condensation and facilitate live steam flow. 

   Doing it again, I think I would build a box with a hinged and sealable top to better handle the pieces but this depends on what you are steaming and number of pieces you need to handle.  Several tips I gleamed from my research - The peices must be removed and go directly to he jig literally in seconds before they start to set; the cooking tme - 1" per hour - varies somewhat with the density of the wood.  I was bending 3/4 x 1" maple and oak strips and found that the oak cooked faster than the maple; and, WEAR GLOVES - the wood is very hot.

   Doug

1. 
   GeoA | Oct 11, 2004 11:30pm | #18

   I was looking for PVC pipe for a downdraft vent and found a place that sells a 20' length of 8" Dia.  for $88.  Seems like a good use for what doesn't get buried is a steam box. 

   Edited 10/11/2004 7:07 pm ET by GeorgeA

1. 
   DougF | Oct 12, 2004 05:00pm | #19

   George,

   There is a plant near me that fabricates insulated pipes by inserted copper pipes in 8  or 10" PVC pipes and then filling it with foam insulation.   The cost of this PVC is about in the range you quoted but it is a very thin-wall PVC.  It will work as a steam box but requires bracing to handle the distortion when the PVC heats up.   You also need to purchase end caps and tee's  of the same schedule.

   Doug

1. 
   GeoA | Oct 12, 2004 06:04pm | #20

   Sounds like an interesting product.  Does this company have a website?

1. 
   DougF | Oct 12, 2004 06:44pm | #21

   George,

   I really don't know if they have a web site.  They are a small fabricator outside of Dallas.  The PVC products they use are widespread for low-pressure applications.  Once you start looking you find a whole world of industrial PVC pipe products.  I had order my metal duct work for my DC system the previous week when I found this shop.  I decide against PVC originally since I could not easily locate PVC in sizes I requied at reasonable prices.  Schedule 40 is very expensive when you get into the larger diameters.  Anyway, I stumbled accross this shop and the owner was more than agreeable to order whatever I wanted since it helped him maintain a order history with his supplier.  It is not the sewer pipe usually found in the box stores and has an interior smooth like a schedule 40 pipe.  When I relocate back to our home in New Mexico in 3 years I will probably use this material in lieu of metal pipe for the DC. 

   Doug 

8. 
   SWW | Sep 30, 2004 08:06pm | #15

   You can find plans in The Chairmaker's Workshop by Drew Langsner.

   http://www.amazon.com/exec/obidos/tg/detail/-/1887374345/qid=1096563948/sr=1-6/ref=sr_1_6/104-1662024-8662348?v=glance&s=books