Advice on building a steamer for steam bending

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badger99

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Hello,

I am about to embark on building a steamer for steam bending wood. It will be used outside, but stored in my workshop standing on its end. I think it will be about 2m in length.

I have done a lot of reading on building one and am caught between a few different build types. I'm writing to hear if others have advice from experience.

Firstly, build type. I would like to insulate it to help with heat retention and efficiency.
- Plywood box. Would this need to be marine play? Its very expensive at £130 a sheet for 18mm from my local yard.
- PVC tube inside another tube. for example a 250mm tube insulated and within a 300mm tube. many people mention PVC going soft and altering in shape when heated.
- A metal tube, for example galvanised steel or aluminium tube thats sat inside a square wood box and insulated in the void.

I know that a square chamber would allow for more wood/larger pieces to be steamed compared to a tube. How would be best to insulate a plywood chamber? could it simply be a foil insulated blanket (the type used in house insulation) that i wrap around it before i begin, of should it be built in.

At 2m, would 30x30cm be advisable or smaller/larger. This size would be larger that i require for the job at the moment, but in the future i will probably want to be more adventurous and would like to build 1 decent unit now, rather than have to build in another in a years time. I plan to use a 6litre wall paper steamer to power it.

As i will be storing it upright and moving it from inside to outside my shop, weight is a slight concern.


Any advice would be greatly appreciated.
 
I have done a bit of a Steam bending and as you propose I used a box, just recently I came across this, recommended by people on another site I am on.
Yes I know he’s American but he does appear to know what he’s talking about – being a shipwright he no doubt does it all the time.

Ian
 
My steam box is a length of galvanised round ducting, its about 10 inches diameter and is capped off at both ends with discs of chip board. it's wrapped in an old blue sleeping bag for insulation. I rescued it from a colleague who was chucking it out.

There is a pipe fitting in the side with a short length of copper tube. This is quite wide, about 28mm at a guess. The steam enters here from a small wallpaper stripper It works well enough either in the horizontal or upright position ( in which case pieces are hung with hooks from the top chipboard end ).
 
4” soil or underground pipe dead simple, for which you just buy the bungs. You just wrap anything around it to insulate it. I use two wall paper steamers from either end with the chimney in the middle. That gets it hot enough.
 
I use boil in the bag. One shipwright I saw used that method to steam mahogany into tight radius curves on a deck-house on the boat as he could develop the curve while steaming.

Some like a return pipe to collect condensed steam and return it to the boiler
 
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I remember having to re-rib a 40 ft trawler, which involved some tight bends.
Used a length of gal down pipe with a 90 deg elbow which sat into the lid of an old gas copper. The pipe was angled up slightly, to allow condensate to flow back into the copper. Used a few rags to seal off the open end - no insulation was needed. Worked a treat.
 
I made one out of 4” Kingspan off cuts. Just cut with a saw and bound together tight with duct tape. Steam provided by wallpaper stripper I had anyway. Worked a treat and cost very little but if course not at all pretty. At 2m long it is a nuisance to store though esp as it is 16 years since last use….
 
Unless you're going to use it for business, i would recommend lashing up a temporary arrangement using the cheapest of materials. There's nothing to be gained from the use of insulation apart from your personal safety. Energy efficiency doesn’t really come in to it. As long as you can see steam and condensate issuing from drain and vent you'll know it's at the max temp of 100deg inside. To gain efficiency you would have to incorporate some sort of feedback control system, which would be way over the top.
My recommendation, as ever, is to try something for your next project (it's difficult to fail on this one) and if you can think of improvements, incorporate them for next time.
Brian
 
I've been mulling over how to make a steamer 'box' for 2 or 3 years, even bought a wallpaper stripper/steamer in preparation and always thought it would be of the 4" plastic pipe variety. Why so long? I moved house and that's a long project. 😰. Having seen the video Cabinetman posted I'm moving towards the poly sleeve certainly to start with anyhows. Good food for thought.
Thanks to all who've posted making it an interesting thread.
Martin
 
Thanks for everyones replies so far. As always it's great to hear peoples experiences and advice. I have located a cheap offcuts of galvanised ducting locally so am currently planning to go down that route.

Next up is to look into building a compressions strap
 
Thanks for everyones replies so far. As always it's great to hear peoples experiences and advice. I have located a cheap offcuts of galvanised ducting locally so am currently planning to go down that route.

Next up is to look into building a compressions strap
Just be aware that any drips from bits that may have lost their galvanised coating will contain a certain amount of dissolved iron, and those drips will react with some woods, Oak, Chestnut for example and leave almost black marks that you won't get out.
For the compression strap, I used galvanised nail strap (think it's called that...) from the builders' merchant, fixed to wood handles and wrapped it in cling film to keep it out of direct contact with the wood.
 
Related question - Whats the best wallpaper stripper steam generator ? I suppose they all do pretty much the same thing, just really comes down to the tank size.

Or are any using something different ?.
 
Just be aware that any drips from bits that may have lost their galvanised coating will contain a certain amount of dissolved iron, and those drips will react with some woods, Oak, Chestnut for example and leave almost black marks that you won't get out.
For the compression strap, I used galvanised nail strap (think it's called that...) from the builders' merchant, fixed to wood handles and wrapped it in cling film to keep it out of direct contact with the wood.
Curious what a galvanised nail strap is? Not something I’ve come across, I’ve always used ratchet strap type stuff.
Ian
 
My steam box is box shaped and welded from stainless steel. It is about 40x8 cm inside I think and 6 metres long. In hindsight it should have been 5 cm wider inside to give room for planks with a greater edge curve. Insulated with foam on the outside. Steam comes from a wood fired boiler holding some 50 litres of water in a stainless tank atop an iron firebox.
Anyway this is overkill for you unless you are going into boatbuilding and want a tight system for indoor use.

I suggest a wooden box nailed together from ordinary softwood boards. If you cannot find cheap boards wide enough use tongue and groove. Then you will need no insulation.
I know nothing about wallpaper steamers. A typical heat source for outdoor use is a large old kettle over a woodfire with a short lenght of pipe ledading from the top to the steambox.

PVC pipes and plastic bags are recommended everywhere on the internet but they cannot stand the heat for long and they have problems achieving a high enough temperature.
 
My first generator was an old pressure cooker with a rubber tube in lieu of the safety valve and a camping stove as the heat source.
Brian
 

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