Advice on building a steamer for steam bending

[Cobbs]

Curious what a galvanised nail strap is? Not something I’ve come across, I’ve always used ratchet strap type stuff.
Ian

As I say, I'm not sure what the right name is, but I know it when I see it. It's about 2" wide, maybe 1mm thick, perforated with holes to drive nails through and galvanised. Comes in rolls of maybe 25 metres if I remember right and is available from any builders' merchant. Also available in 1", which is the most common, but 2" makes a better bending strap. I would post a picture, but this ruddy computer doesn't have a slot for a memory card, so I'd have to take a photo, then go indoors to email to myself before I could post it. My phone doesn't do that sort of thing, being a steam powered model...
You may well be right about the nylon ratchet type stuff being better, I just used what I had to hand, years ago.

 

[badger99]

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.

Thanks for this advice. As Cobbs mentioned the staining from galvanised if/once the surface breaks. And to save on insulation, i am thinking to build a box from softwood. I have read that pine is fairer hard to bend, am i correct in thinking its fairly stable to use as a material to make the box? and would 18mm be thick enough if i were to make a 300x300mm box?

For the compression strap i found this 20mm stainless steel banding: https://www.toolstation.com/stainless-steel-banding/p48657 its 0.9mm thick, would this be suitable? ad does anyone have images or can point me in the direction of how to make the ends of the compression strap?

Thanks,

 

[Cabinetman]

@Cobbs brill, yes that’s handy stuff for lots of things thanks.
Ian
@badger99 well it depends on what and how you are applying the pull force, but anyway save yourself £20 and use an old bit of lorry ratchet strap or webbing, trapped between two bits of wood- that should get you headed down the right road.

 

[cowtown_eric]

I had to steam bend door jambs once upon at time, so I needed at least 8+' Mould made, stainless steel strap obtained Box made of ply, ends packed with FG insulation, and box wrapped with bubble type aluminum insulation.

Glue was in tray, roller at the ready, as wee clamps

Resawed many straight-grained pieces, if I recall 3/16" thick. at least 9' long, 7" wide or was it 7.5"-I forget

For steam, I suspended a cheap deep frier under he box near where the curve was and let er rip. It doesn't shut off at boiling point but you do have keep pulling it out to refill In hindsite I should have incorporated a second deep frier for added steam heat.

Shoulda takem pictures of process, but all I could find was finished product

Aluminum sill, modern weather stripping

and installed

And ja, I made the curved mouldings too!

Incidently, the door was heavier than it looks, and I had to install two ratchet hoists from ceiling when test fitting and fettling for a good fit!

 

[heimlaga]

Thanks for this advice. As Cobbs mentioned the staining from galvanised if/once the surface breaks. And to save on insulation, i am thinking to build a box from softwood. I have read that pine is fairer hard to bend, am i correct in thinking its fairly stable to use as a material to make the box? and would 18mm be thick enough if i were to make a 300x300mm box?

For the compression strap i found this 20mm stainless steel banding: https://www.toolstation.com/stainless-steel-banding/p48657 its 0.9mm thick, would this be suitable? ad does anyone have images or can point me in the direction of how to make the ends of the compression strap?

Thanks,

I have never steam bent any other wood species than our local spruce (Norway spruce to the English) and cannot comment on how other species bend.
I have never used a compression strap either. It is unecsessary for boat planking and ribs. Therefore I cannot give you any advice. It is outside my experience.

If you support the spruce or pine steam box properly on the outside it will not steam bend itself. For instance if you place it on top of two 2x4s. However my first steambox which I built in my teens was a tongue and groove box 5 metres long and supported only at the ends and it steam bent itself until pretty much useless.