Set-up for steam bending wood?

[Andy Kev.]

I'm thinking of making some things that require curved bits of wood. The conventional method appears to be steaming.

Does anybody know of a safe set up for doing this? I envisage bending nothing longer than 3 feet. What are the normal parameters e.g. if you had a two foot bit of hardwood 1" x 1", how long do you steam it for to make it bendable?

As you can see, I don't know even the basics of this subject.

 

[AndyT]

The simplest diy setup on a small scale is an offcut of soil pipe and a wallpaper stripper. Plug the ends loosely and put the pipe on a slight slope so condensed steam can drip out safely.

Wood should be as green as possible.

 

[Andy Kev.]

Andy, thanks: but what about the nitty gritty of getting the steam into the pipe? Or does one heat the pipe up?

I've got a fairly powerful camping cooker with which I could heat up water in a vessel to produce steam.

And how does the wallpaper stripper come into it?

The wood I was thinking of using is some cherry that I have but it is fairly seriously dry. I'd be prepared to get a new board though which would have much higher moisture Content.

 

[Argus]

Well, here’s a puddle of knowledge with a very deep end.

The idea of steaming wood to make it pliant enough to bend to a shape is very basic – apart from water, you will need two basic items:
An apparatus to generate steam, then a container for the wood and hot vapour. Lots of these, of varying complexity and, dare I say, safety, are in print and on YouTtube.

What is mostly considered in chairs and the like are sections with a narrow cross-section: consider about one inch square or thereabouts as the practical limit for absorbing steam and bending on a static jig. Wider boards need elaborate bending apparatus.

Next, you’ll need a set of jigs or formers, straps, wedges levers etc. to form the hot, wet wood to the desired shape. Make this yourself.
Finally, you need to consider the wood you are about to bend and you’ll discover the numerous complexities and uncertainties, so be prepared for a rate of failure amongst the successful bits.

1 Some woods will bend readily – some won’t. Select your local species with care.
2 Previously dried woods, especially kiln dried woods, don’t like having water vapour reintroduced into their fibres and tend not to absorb it at all or in varying amounts. Not the best stuff to bend reliably.
3 Failure-rate. Be prepared for bits that split…. Sawn timber especially the stuff with a varying grain-direction will always want to split along the weakest line of growth.
4 BE SAFE; THIS STUFF WILL BE HOT AND WILL BURN – so think about skin protection.

So, what woods bend successfully?
Without going into species that may not be available to you, in an ideal situation you’ll need fresh-cut wood that has not been seasoned, so that it still contains an element of the moisture it grew with, and is straight-grained – best of all split or riven, not sawn. Remembering again that some species bend well and others do not.

Lots of trial and error and experimentation is on the cards until you get the feel of it. A bit like re-inventing the wheel: you can see one on your bike – now make one.

Plan B? An alternative to steam-bending, though still requiring the same jigs and frames, is to laminate and glue thin strips. Most woods at about a few millimetres thick will form and glue to shape; cut well most joints will be barely visible. You may use this method for forming wider sections....
Hope this helps and good luck.

 

[Yojevol]

I started my steam bending activities with a camping stove and an old pressure cooker. The steam is transported to the steaming tube with a rubber pipe fixed to the pressure cooker pressure release valve nozzle on the lid. I've since moved to the wallpaper steamer stripper approach simply because plugging that in and switching it on is much quicker than dealing with the old Gaz stove. I've got my 4" plastic tube in an insulating wooden box, but this is not absolutely necessary for a small set up. It's a good idea to have some form of support inside the tube for your timber so it's not sitting in the condensate.
You will need to experiment with your cherry to find out what you are capable of bending. For 1" thickness you will probably have to leave it steaming for an hour or so. I think you will have trouble in bending a 2' length, you just won't be able to get enough leverage.
Having said all that I've moved over to laminating because it's more predictable although it does take more time in timber preparation
Good luck, happy steaming
Brian

 

[Andy Kev.]

Yoyevol,

now I understand the reference to the wallpaper stripper!

Argus,

here's a bloke going through much of what you said:

https://www.youtube.com/watch?v=_Lpu8w_QLng

Research continues, as they say.

 

[Argus]

Some 30 odd years ago, a book appeared by John Brown about making "Welsh" Stick chairs.

It's been out of print for many years, but was recently republished by Lost Art Press. I recall that there was a very clearly-written section on John Brown's steaming set-up in that book. Substitute a wall-paper-steamer for his boiler arrangement......

Their blog has a shorter version listed here with the fundamentals of his approach.....
https://blog.lostartpress.com/2018/06/2 ... air-parts/

 

[Sheffield Tony]

Here's how I did it:

first-chair-t82109.html#p896243

- it works, but PVC slowly sags with steam temperatures. I now use a length of aluminium pipe instead.

For green ash legs of about 1 1/2" diameter, the steamer holds just about enough water that you can fill it up, plug in, and it's ready when the steamer cuts out because it's run out of water, about 75mins. Bending needs a sturdy former and some big G clamps.

 

[Nigel Burden]

Yoyevol,

now I understand the reference to the wallpaper stripper!

Argus,

here's a bloke going through much of what you said:

https://www.youtube.com/watch?v=_Lpu8w_QLng

The wallpaper stripper Andy is referring to would be a steamer. It is basically a plastic tank with a heating element an a plastic tube with a plastic plate which you place against the wallpaper to be removed. This plate has a rim so as to trap the steam there for softening the glue.

https://www.aldi.co.uk/ferrex-wallpaper ... lsrc=aw.ds

Research continues, as they say.

Nigel.

 

[marcros]

how bendy do you need it? profchris (I think) has done a couple of WIP on guitar sides using a bending iron. there will be limitations, but it may be appropriate.

 

[Andy Kev.]

Sheffield Tony,

thanks for the link.

Andy T,

the reason I was baffled by your reference to a wallpaper stripper was because I thought you meant one of those scrapers. Oops.

Marcros,

not terribly bendy. I'm thinking of having a go at one of Christopher Schwarz's staked chairs and it would be for the back rest, arm rest etc.

In any event, I'm not in a hurry about this as I've got a few other things to do first. At least I now know what's involved in the actual steaming device.

 

[Inspector]

Lee Valley has a free booklet you can download. Several books you can buy and there are others on Amazon etc. A steam generator you can buy if you have 110V power but I assume something like it is available in England. Lots of information in wooden boatbuilding books and magazines.

https://www.leevalley.com/en-ca/shop/to ... on-booklet

https://www.leevalley.com/en-ca/shop/to ... -generator

Pete

 

[AndyT]

That second link leads to something very very similar to the popular Earlex wallpaper stripper. But Lee Valley are asking $94.50 for it!
Even B&Q only want £32!

 

[Sheffield Tony]

Interesting. earlex.com lists the SS77 steam generator at $69.99 plus the brass fitting for $19.32, so about same price. It seems not exactly the same as the wallpaper stripper - 1500W vs 2000W. But I can vouch that the wallpaper steamer works fine, and looks like better value ! Cheaper brass fittings are available ...

 

[Inspector]

Any self contained steam bender will be similar. Amazon has the same bender for $115Can so the LV price is a bargain. I really referenced it so the OP can look for something similar.

I have a steam generator that you use a big propane torch to heat it. It is for melting frozen pipes, drains, culverts etc. I had them add a threaded fitting so if I wanted to steam bend someday I could add a water line to it. http://www.arcticblaster.com

If The OP does enough reading first he will find there are lots of ways to generate steam and make steam boxes.

Pete

 

[El Barto]

Andy if you fancy making the trip to Andover I’ll happily take you through my steam bending setup and now it all works.

 

[Hand Plane]

I have done steam bending several times with different woods, typically around 25 - 35mm thick, eg for tub chairs.

One thing I would recommend is a flexible metal strap for going round the back of the wood being bent as this provides constraining forces over the outer side of the wood (in tension) and helps (no guarantees though in this game!) it from cracking.

Look at the James Mursell videos on his Windsor Workshop site. Note the forces involved. James has a smart rig, but he's using it on regular courses.

https://thewindsorworkshop.co.uk/miscel ... ng-videos/

There are other videos on youtube, and the common factor is the band round the back. Note the wooden blocks attached to the strap as these compress and contain the length of wood being bent.

Getting a suitable strap is a pain and expensive. When I was at college we had a 3" wide, by 8' long stainless steel strap. We would have a guy on each end, and at least one fixing the clamps and wedges.

You can manage without a strap. I have done bending with formers made with lots of holes in them ready to receive the clamps around the bend. I agree with the earlier posts above. You have to be quick, and the more hands the better!

 

[profchris]

how bendy do you need it? profchris (I think) has done a couple of WIP on guitar sides using a bending iron. there will be limitations, but it may be appropriate.

Ooh, I've found out who my reader is

Using a bending iron I'd not go much thicker than 2mm, and then only in friendly woods. For the OP's plan, that's around 12 laminations. And it takes practice to get the bends uniform

However, for shallow bends you could make a former, clamp one end of your 2mm strip to one end, and then heat it with a heat gun until it eases into place. Clamp the other, leave a few mins to cool, repeat. Maybe 60-80 mins including glue up.

 

[Racers]

Wait until Aldi/lidl have there wallpaper stripper it’s usually under £20!

I made a stern box from OSB it held up fine.

Pete