Steam bending or laminating stripes, when, how and why?

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Yesterday’s night I couldn’t sleep so I got up and started sketching and I came up with a design of a small double deck table ( sort of) for the entrance of a flat/house. You know, the one you leave the keys and the mail on.

I can foresee that if I make it it will problably involve either one of those techniques or maybe both.

Being a complete ignorant about both, here go my questions:

How to decide which one to use, why and where? Does it depend on the type of wood used? On the difficulty of the bending? On both and something else that I don’t mention because I don’t know?

Has any of you had a go on those and what where your results??

Any input will be greatly appreciated. Thanks in advance.
 
toni,
i bend stuff all the time and very rarely use steam for a couple of reasons;
1) steaming takes longer than strip laminating for me
2) with strip laminations i have very little if any springback

edge grain is an issue with strip laminations, the strips do show unless you veneer over the edge or cut a profile to hide the laminations.
the major deciding factor for me is springback. a steam bent piece that is not restrained after bending will try to return to somewhere near its original shape, if you bend a piece into a "u" let it cool and remove it form the form and leave it unrestrained it will turn into a shape somewhere between a "u" and an"L"....where this movement stops (if it ever does?) depends on the board and the enviornment....if you where to split wood staves from the same oak tree and steam them the same amount of time under ideal conditions, place them in identical forms, dry them in the same room then turn them loose each would behave somewhat differently...
whereas if you take kiln dried oak and cut 1/8" laminations and glue them around a form even with pva glue and set them side by side they will remain very similar if not identical,(it depends on the radius of the bend and number of laminations).....the more glue you introduce into a bend the more stable that bend becomes....
hope this helps? tod
 
I've only done the laminating so cant really comment on the steam. Ditto here with springback being pretty non-existent. One other thing I've seen done with laminating that I'd like to try someday is using 1 or 2 thin strips of a contrasting wood in the lamination. I've seen pics of some items somewhere and it was a pretty nice looking effect.
 
Hi Tod.

Thanks for your input. Besides that I think that taking the hassle of building a steam box only for one piece would be too time consuming, and I would have to build the jigs and molds as well, while using strips only the molds and jigs are needed.

Only a couple of more questions if I may.

I presume that the thickness of the strips depends on the flexibility of the wood plus the radius of the bend to be achieved, but is there any sort of recipee such as for a radius of xx thickness aa or let's say an allterrain, mostly used thickness?

And second, do you plan or sand to a smooth finish the strips before laminating them??
 
Only a couple of more questions if I may.

I presume that the thickness of the strips depends on the flexibility of the wood plus the radius of the bend to be achieved, but is there any sort of recipee such as for a radius of xx thickness aa or let's say an allterrain, mostly used thickness?
And second, do you plan or sand to a smooth finish the strips before laminating them??

toni,
as to thickness.....it all depends on the radius and type of wood as well as the number of laminations.....as a general rule if you can`t push the laminations to the form with moderate hand pressure go thinner.
as to sanding........the only time i sand is if i`m scared that the thickness planer might blow up a thin lamination(i go to 1/8" regularly)....if you have the ability to thickness sand accurately ie; widebelt, then go no finer than 60 grit so as to give the glue some "tooth"........for most laminations i go right from the planer to glue-up.
tod
 
If the strips are relatively small (a meter or less) I'll hand feed on a bandsaw (any larger and I have to deal with the inevitable speed bumps and irregularities of having to stop and change hand position), and so for larger pieces, and/or alot of them -- I will hook up my power feeder to the bandsaw. In either case, the consistency is terriffic so no need for sander or planer, and when using a carbide blade, the fuzz left behind after the cut is perfect for glue. See below:

03-Cutting-Lams-02.jpg


03-Cutting-Lams-07.jpg
 
I've done some gentler curves too, but dont have pictures of those. This one had a mixture of curve sizes, most of them pretty tight. I did what Tod suggested and tried different thicknesses on the various curves until I found what seemed to work for the radii. I ended up using 1/16" on the tight ones for the lower gridwork shelf and 1/8" for the apron and the thicker lower stretcher. I used male and female forms but if I had to do it again, I'd also add some sort of alignment runners on the forms to draw them together straight when clamping. Having the male and female form, plus the glue covered laminate all trying to slide around while you get it clamped is a bit daunting. I dont have any pics of the forms but made them out of MDF and put a facing of plastic laminate on them so glue wouldn't stick.
HalfmoonFront.jpg
(The white junk on the bottom of the front leg is just some wierd reflections from the floor)
 
I forgot about another technique. Luthiers use heat a lot (a hot pipe, heat blanket & controller, etc) to get incredibly tight bends for musical instruments. I think if you needed something really tight you could use one of those methods to pre-bend the pieces before applying glue to laminate them.
 
Hi Dough.

Thanks for posting the pic of your small table, I like it a lot, the concentric rings on the lower deck are a great eyecatching detail, I bet they took you quite a while to make;).

Is the central top part some sort of marble or leather?? and the black dots on the leg joint are they wooden pegs or just plugs to cover a hidden screw?

Wonderful job!
 
A common misconception of bending wood is that you need to use steam. That is not quite true. While someone mentioned heat, what really works well is using boiling water. In fact boiling water works better than steam to bend wood as it saturates the wood fibers better and makes for an easier bend. The problem is of course, having either a boiling pot big enough, or a wooden part small enough to fit into the pot of boiling water.

I am not sure the size of the piece you are trying to bend, but boiling water may just work better for you. It also saves a lot of work building a steam oven for the piece. I have used boiling water on some of the wooden models I make with a lot of success. You still will have the problem of springback, or "memory" as the official term is called though.

I am not saying strip lamination is not the best way to go however, just throwing out another option you may not have heard about.
 
Hi Dough.

Thanks for posting the pic of your small table, I like it a lot, the concentric rings on the lower deck are a great eyecatching detail, I bet they took you quite a while to make;).

Is the central top part some sort of marble or leather?? and the black dots on the leg joint are they wooden pegs or just plugs to cover a hidden screw?

Wonderful job!

The top panel is 1/2" Corian (actually Wilsonart) that sits in a rabbet on the cherry outer rim. There's a brace for a little extra support that goes from the back of the front leg to the back apron piece. There's also a middle stretcher on the lower shelf not visible behind the leg going to the back stretcher. The dots are some Paduak pegs I made through the tenons. They're not black but the end grain did darken up a lot more than the same thin Paduak inlay on the top.
And yes, I spent way too much time on that table.:D

Travis mentioned something I neglected to mention. I don't know that this was necessary, but I did a sort of pre-bending. I soaked the complete laminate stack (with spacers between the leaves) in very hot water for about 20-30 minutes. Then pulled it out, wiped everything dry, then re-stacked it and clamped it into the forms and let it sit for about a week to dry off any excess water. When I pulled them out of the forms to do the glue up, they retained about 1/3 of the curve shape already. I thought maybe this might help minimize springback and had come concerns about the 2 smallest radii curves being so tight, but I'm not sure that it was needed.
 
Wow :eek: Tod. That is a big bent piece! are you planning to use it like that or it is going to be cut in smaller ones?.
It looks like a part of a boat hull, I'd love to see the final piece of furniture you're going to make out of it.:thumb:
 
Great!

I've got a metal spiral staircase at home that I'm thinking about changing for a wooden one.
I hate the present one, it is made of cast iron steps and as it is serial made and as it didn't fit perfectly they had to finish it with three and a quarter steps of masonry; and when you climb up and down it rattles and sounds.

I don't know who made the slopiest job, the mason or the staircase manufacturer, the previous owner fell in love with it when he saw a picture on a home decoration magazine and he didn't hesitate to order one.

Another project on the list, I hope you don't mind asking for your advice in the future regarding that.

Thanks
 
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