Thread: Steam bending (again)

Ya should have chucked a couple of snags on the BBQ while you were waiting.

Arron

Multiplying the steaming time by 50% halves it ??????????

It would also be nice to know if the articles from the net helped

bloody brilliant!

Love the idea and have several applications now for the method.

To get ideas about how to bend the curved panels in a sleighbed I am making, I visited a guy in Moama (NSW, near Echuca) who has a steam bending business - a nice bloke, but I came away believing these panels were just too big to steam bendc - your project has given me an idea!

Thanks heaps Arron

Steve, they sound like pretty big panels. Just how big are they ? I think I would be laminating those - especially if you cant see the edges - I steam bent my chair back because the edges would be the first thing you would see from above so I thought it would have to be one piece. Panels, I would still laminate.

Arron

A good post! My attempts at steam bending (recently, with blackwood, and silver ash) have not proved successful, but have hit some fo the same issues.

1) I too used my Weber having found my gas BBQ and regular fires didn't give enough heat - though for me the head beads gave out much more heat than a regular fire
2) Also time in steam box was much more than the "received wisdom" suggests. (at the "requisite" time I pulled the timber out and it had NO bendability)

Before I try again, I want to solve a couple of puzzles:

1) It seems (according to the book - if the timber is properly steamed?) that it should bend relatively easily (i.e. by hand pressure ... wearing gloves, of course) yet I have never got close to this degree of flexibility.

2) Do you have to use "green" timber? -- my attempts have all been with air dried or kiln dried timber and I'm thinking this might be a reason why bending was so hard and shape retained only a low percentage of shape bent.

3) I read an article where pressure applied longitudinally along the wood during bending is the trick (v. hard to do in a small shop set-up).

Any additional help appreciated.

Hi Ian,
My understanding is that kiln dried timber of any sort is just about impossible to steam bend. Its so dry to start with that there is no moisture to carry the heat through, so even after a good steaming it is more likely to crack. I think that would almost definitely be the source of your troubles. Air dried is better. Green wood is best - much better - but what use is bending green wood if you are then going to use it for joinery - no use at all unless you are then going to season it for a year or two before using it. I think the fact that you and I both had over-dry timber was the reason we needed such long steaming times.

My understanding is that spotted gum is one of the easiest bending timbers. This is due to its very long grain, apparently. I think my next step will be to get some spotted gum (air dried) and experiment with that. Once I am bending it easily, I'll go back to the harder woods that interest me more. I believe jarrah is not bad for bending.

I am interested in your comment about heat beads being hotter though - what brand did you use ? I would like to use something a bit less smokey as I am probably on thin ice with the neighbours already.

cheers
Arron

Hi Arron and Ian,
this post is of immense value to me. I have a pice of silky oak 2400 x 200 x 35mm thick that I am going to bend. Note the positive thinking. Putting it through the thicknesser I had quite a bit of tear out due to its dryness. My woodwork teacher told me to soak it for a couple of hours in water with a little bleach, to prevent later mould, and then thickness it.

It suddenly occurred to me that this might be a good way to start the steaming process - with an already saturated piece of wood.

What do think?

Phil:confused:
ps Arron whereabouts in Sydney are you - do you need a stoker?

gday again all

yeah, the panels are big - what I have resolved to do is: use cherry veneered super-bend ply(rest of the bed is 200+yr old European Pine)......I will be laminating several thinner pieces (with an ash veneer core - FAR cheaper than Cherry) together to get the thickness. This stuff dry-bends beautifully so I'll make formers and glue the panels up.


.... the finished product will look good I feel, though I havent made a sleighbed before and it is proving to be a BIG challenge to get the proportions "perfect".

The very-general style is similar to the attached stunning pics, though mine has far more pronounced curves - very "swan-neck-like" posts, and more 18th century country in feel ...... bloody hard to explain.

But either way, fun fun fun.... and a great project/learning process. So far I have made the four corner "posts" and the front top-rail, which required lamination in 3 pieces and a LOT of hand shaping/sanding

I recently posted this in the "Timber " forum, but clearly the wrong spot. Also there must be a lot of published infomation out there, so any direction would help.
Can anyone out there help me with either a good reference to the bending properties of Ausssie timbers, or offer any advice? I am planning a small desk as shown in the attached images and the legs will need to be laminated/bent. I anticipate 4 plies of 6 mm being the base structure. Bend radius circa 100 mm. Second image follows

This is the front elevation, this time dwg is to scale.

very funky - is that the writing surface at the front?


If you think its worth it, it may be worthwhile to call Period Home Renovator magazine and ask for the name and number of the "bending guy" in Echuca/Moama - give him a call and ask which timber would be best for steam bending. (They did an article on him in the last 2 years)

Jacko,

For general information on bending wood, there is a Fine Woodworking book published by Taunton Press "Bending wood". For data on Australian wood properties, consult "Wood in Australia" by Keith Bootle. There is also an excellent article by Lon Scheinling in the August 2003 issue (#164) of Fine Woodworking on bent laminations.

I would say that you would have no hope of bending 6 mm plies to a radius of 100mm. To achieve that tight a curve you either need to use steam bending, or else use much thinner plies for a glued lamination. The Fine Woodworking article suggests a trial-and-error method for determining the appropriate thickness of the plies. The method is as follows: Cut a piece of wood to the same lenth and width as the lamination, and plane one face flat.
With the planed face against the bandsaw fence, resaw a test piece about 4 mm thick. Use double-sided tape to secure the slice, smooth-side down, to a piece of melamine. Then run it through a thicknesser to produce a lamination about 3 mm thick. remove from the melamine and test whether you can bend it with finger pressure around the convex side of your form without the lamination cracking. If not, re-attach to the melamine and plane away more wood until you can bend it satisfactorily.

Note also that PVA glue is not satisfactory for gluing bent laminations, because of its tendency to creep; you need to use urea formaldehyde glue with a liquid hardener, obtainable from Timbecon, or else epoxy.

Rocker

Seriph, yes that is a (narrow) writing surface, about 280 mm wide, just for writing cheques and small note etc. I will give echuca/moama a try, thanks
Rocker, thanks for the input. I was assuming that I would need to steam the laminations at the curved zone, put in form, then use the form plus laminations as the new form etc. When dry, glue up using AV 201.
Is this doable in your opinion?
Jacko