Steam bending Large timber

[JDGreen]

Hi all,

I'm fairly new to woodwork and I have a project I'm looking to complete next year which requires the need for some simple curve supports that will need to bear a bit of weight. I know my options are bandsaw or steam, but appreciate that band sawing the shape will potentially leave a lot of small grain that may struggle with supporting weight so I'm thinking steam is the answer. My issue is that I'm wanting to do do this to pieces that will be about 3" x 3" by about 1m long.

Just wondering if anyone has any experience/tips of/for bending lumber of this dimension?

I'm new to forums so apologies if in the wrong place or waffled too much!

Thanks in advance for any responses.

Joe

 

[worn thumbs]

First of all,welcome to the forum.I suspect you will get a range of replies and they may differ a bit,the best solution is likely to be in among them.Its interesting that you are bilingual when it comes to measurements and it hopefully indicates that answers involving either sort of units will make sense to you.
The simplest solution is sawing to shape as it takes just a bit of time on a suitable bandsaw,but you have already identified the potential problem of short grain.If we knew what amount the piece deviated from straight it might be helpful as a 50mm deviation over a metre might be achievable with a board that had a grain structure that followed the curve-more or less and a 300mm deviation would be less wise to saw from solid.
We don't know what species of wood you have in mind and not all of the steam equally well.Green oak is one of the best but again all timbers have limits to how much curvature you can persuade them to take and 3X3 will need rather a lot of force to get it to bend no matter how sharp the curve.The length also works against you as at a metre long you won't have much leverage and will have to arrange some sort of contrivance to apply the force while the wood is secured to a very strong bending form.So in order to even start the job you need to build a bending form and arrange a suitable steam generator,coupled to a steambox .
Have you considered laminating?It would be my choice as its a fairly straightforward job to build a laminating form.It also means the grain follows the shape and can be done in stages if necessary.On the negative side there is a bit of cleaning up to do when complete and I would guess that 3 1/4" wide strips would be a sensible minimum.You do need enough cramps although you can supplement them with thick plywood horseshoe shapes and wedges to apply force.

 

[Woody2Shoes]

Hi - definitely +1 for investigating the laminating option. Cheers, W2S

PS you haven't said what timber species you're thinking of - not all are good for steam-bending (and you need really good quality straight-grained stuff to maximise your chances of success too).

 

[Lazurus]

Laminating for me to.

 

[JDGreen]

Thanks both for quick responses.

Material wise I'm thinking Ash or oak as I'm aware that these take to steaming better than other species.

Not sure on the actual curve distance yet as at the moment it's just an idea and waiting on measurements from the client before I can begin the design process and figure out the curves.

Lamination hasnt been completely ruled out, just wanting to put the feelers out and gain insight from people's experience.

The bilingual measurements are just due to watching too many videos from all over! I should be working in mm really being a brit!!

Thanks again,
Joe

 

[Droogs]

If you're doing for a client the method used will in all honestly come down to cost. If cost were no object then you could bend solid beams 6x6 to a surprisingly tight radius by first pre-shrinking the beam longitudinally, using a hydraulic steam press to about 80% its original length, This would then allow you to cold bend it over a former of suitable strength and radius without much risk of breaking or splitting. This method also gives very little spring back as the cells of the wood tend to stay put once bent. Bending process after shrinking can be seen here:

https://www.youtube.com/watch?v=QspGC1_bhHw

Other methods have a good bit of spring back and this needs to be taken into account in how far you bend the wood (each species being different). Of the other methods regarding time/cost/space lamination is probably the best overall process IMHO. You will still need to make formers and have a lot of clamps unless you use a vacuum press for the glue up stage. All are slow. If the item has any load bearing to do I would not recommend sawing as it is too unpredictable in the probablity of the wood failing at some point.

hth

 

[JDGreen]

Thanks all for your replies.

Cost will play a factor to some degree but as its for a display/structural purposes obviously don't want to scrip too much to the point it looks naff / isn't suitable. Client would like walnut but I'm aware that this isnt going to respond too well to bending.

What are peoples views / experiences of adding veneer on to bent items? Will spring back over time affect this? I'm assuming so.

My thoughts so far based on answers here and research are probably laminated oak would be best for the project?

Tia,
Joe

 

[GarF]

Lou demonstrates both approaches in these clips. The timbers are probably similar dimensions to what you're proposing.

https://www.youtube.com/watch?v=50uXPPt8-VI

https://www.youtube.com/watch?v=7JFePos8RQQ

Enjoy. I could listen to this guy all night. In fact, I think I may.
G

 

[Jacob]

.....
My thoughts so far based on answers here and research are probably laminated oak would be best for the project?....

If you are veneering it then laminated softwood would be fine. It's a common combination in older furniture. But veneer is no good for load bearing unless the dimensions are well above minimum to avoid bending/flexing which could pop the veneer off.
Wossit for exactly?
PS there is a halfway house where you steam bend the laminates first and then glue/clamp them.

 

[custard]

I'm fairly new to woodwork...

Hello Joe, I've lost count of the number of times I've read similar words on this forum, "I'm new to woodwork, but despite having minimal skills I want to do something that's really rather tricky".

It's one of these "known unknowns" versus "unknown unknowns" type of things. Being so new to woodwork you don't yet know all the dozens of different ways that both steam bending and lamination work can go horribly pear shaped!

The most sensible advice is go back to your plan and design out the curves.

 

[worn thumbs]

Jacob's suggestion of steaming the laminates and then gluing is a possibility,there is a significant problem though.A lot of glues are quite intolerant of excessive moisture content and freshly steamed timber is inclined to be a bit moist.It would need a fair amount of time to stabilise and clutters up the workshop while doing so.
Given the choice of using oak or ash for the job,I would choose ash for laminating as it is more reliable.Oak can be a bit tricky with some glues and I fully expect a lot of criticism regarding this point.The likes of Aerodux or Cascophen are the best for strength but you will have a visible purple glue line with them.
Is the finished article intended for outdoor use?That can also shade things a bit.

 

[JDGreen]

Thanks for the info. Not intended for outdoor use. They're a set of bespoke speaker stands for my studio. So I'm also having to research and factor in the various acoustic qualities / issues. Full aware of bitten off more than I can chew, but I work well with a bit of pressure and the client is a friend so a good test ground for a project such as this!

 

[JDGreen]

I'm fairly new to woodwork...

Hello Joe, I've lost count of the number of times I've read similar words on this forum, "I'm new to woodwork, but despite having minimal skills I want to do something that's really rather tricky".

It's one of these "known unknowns" versus "unknown unknowns" type of things. Being so new to woodwork you don't yet know all the dozens of different ways that both steam bending and lamination work can go horribly pear shaped!

The most sensible advice is go back to your plan and design out the curves.

Thanks for the words. I know the design roughly and just need final measurements, but I know the cruves aren't going to be tight. I will concentrate on the design and figure out final curve measurements etc in great detail before embarking!

 

[JDGreen]

Lou demonstrates both approaches in these clips. The timbers are probably similar dimensions to what you're proposing.

https://www.youtube.com/watch?v=50uXPPt8-VI

https://www.youtube.com/watch?v=7JFePos8RQQ

Enjoy. I could listen to this guy all night. In fact, I think I may.
G

Thanks G, I'll give those a watch a few hundred times between now and starting the project!

 

[MikeG.]

Welcome to the forum, Joe.

You've got some really experienced guys answering your questions on here, and some professional woodworkers. Custard is a pro furniture maker. I have been too, as have others in this thread. It is important that you know that you are getting some really sound advice from experts.

I wouldn't attempt to do what you are planning, the way you are planning it. The only possible method I would consider for that sized final result is lamination. I've been woodworking for 40 years, and steam bent a number of pieces. If I have a lifetime success rate of 50% with steam bending timbers over 25mm thick, I'd be surprised.........and my recent efforts would be getting on for 90%. You can see from that how successful my early efforts were! I wouldn't even contemplate bending 3" timber. You can watch all the youtube clips you like, but when you're trying to force a piece of steaming hot wood into a shape it doesn't want to go, waiting for the noise of it cracking whilst wondering how the hell you're going to get enough grip on it to force it onto the former, you'll wish you had opted for laminating.

 

[MikeG.]

......... Full aware of bitten off more than I can chew, but I work well with a bit of pressure..........

How well do you work without skills, knowledge or experience, though?

I don't mean to sound off-putting, but I wouldn't want you to think you can take this sort of thing on lightly. I doubt you'd be too encouraging if someone who had never played the guitar said "I've seen some youtube clips and I want to come and do some recording in your studio".

 

[JDGreen]

Welcome to the forum, Joe.

You've got some really experienced guys answering your questions on here, and some professional woodworkers. Custard is a pro furniture maker. I have been too, as have others in this thread. It is important that you know that you are getting some really sound advice from experts.

I wouldn't attempt to do what you are planning, the way you are planning it. The only possible method I would consider for that sized final result is lamination. I've been woodworking for 40 years, and steam bent a number of pieces. If I have a lifetime success rate of 50% with steam bending timbers over 25mm thick, I'd be surprised.........and my recent efforts would be getting on for 90%. You can see from that how successful my early efforts were! I wouldn't even contemplate bending 3" timber. You can watch all the youtube clips you like, but when you're trying to force a piece of steaming hot wood into a shape it doesn't want to go, waiting for the noise of it cracking whilst wondering how the hell you're going to get enough grip on it to force it onto the former, you'll wish you had opted for laminating.

Thanks for the response Mike. I appreciate and take on board all advice I've received so far and am under no illusion that I'm not being gifted with information from knowledgeable people / experts in the field. I really appreciate the fact that you've all stepped forward to help me and offer advice. I will definitely be laminating the pieces based on responses from the forum. Do you/anyone have any advice on top of what has been suggested for best materials and glues to use?

Thanks again for all the responses.

Joe

 

[JDGreen]

......... Full aware of bitten off more than I can chew, but I work well with a bit of pressure..........

How well do you work without skills, knowledge or experience, though?

I don't mean to sound off-putting, but I wouldn't want you to think you can take this sort of thing on lightly. I doubt you'd be too encouraging if someone who had never played the guitar said "I've seen some youtube clips and I want to come and do some recording in your studio".

I appreciate where your coming from Mike and fully aware of my current skill level and an not taking lightly hence all the exploration before commuting to anything. But we all need to start somewhere and learn at some point

 

[JDGreen]

My spelling was terrible in that! I apologise!

 

[MikeG.]

.........Do you/anyone have any advice on top of what has been suggested for best materials and glues to use?.......

Yes. Pick your ash really, really carefully. You really don't want grain running out of the line of the laminations, because that's where it will kink or break. Your surface preparation has to be spot on (have you got access to a planer thicknesser and/or a thicknessing sander?) I don't think the glue is terribly important, but be careful that you use one which dries clear, not brown (so beware of which Titebond you go for, for instance). But the biggest tip I can give you is to make a few trial pieces, and, as with every woodwork project, have more clamps than you'll think you could ever need.