WoodworkerDopers: help me bend wood, please

Factual Questions
1

Hello all,

I’m trying to build a spherical armature for a sculpture piece, roughly 18-20 inches in diameter. What’s the best way to make wood flexible? I vaguely recall hearing someone say that I could soak it in an ammonia and water solution, but I can’t recall where I got that, and have no idea what the proportionate amounts should be.
I went by a lumberyard today, no one had any helpful suggestions. I ended up buying some strips of pine that are maybe 1/2" wide and 1/4" thick.

Thanks!

Peace,
~mixie

2

The only way I know of making wood flexible is to steam it overnight.

3

hmm… how do I steam it? I’ve got a five foot section, two three and a half foot sections, and two two-foot sections.

~mixie

4

You could do it by laminating veneers; if you cut your wood lengthwise into very thin strips, they will be much more flexible; you bend them around a former and glue the layers back together in the bent form.

Pine isn’t the best timber for steam bending.

5

How to make a steam box.

6

What is the best? The only other suggestion they had was plywood or masonite, but I’d have to buy a whole lot of it that I don’t need; I think they said the minimum was half a sheet for $30. The pine was only fifteen cents a foot, so if I have to buy something different, it’s not a big deal.

Peace,
~mixie

7

Go get yourself some Bending plywood. It is smooth on one side and kerfed on the other and if you are just making a simple curve or cylinder it will be perfect.

OTOH, if you go to Home Depot, check out the masonry section (right next to the lumber) and check out the thick cardboard forms for pouring concrete columns (aka Sonotubes). You might just find one in the right diameter and all you will have to do is cut it to the proper size.

8

Hardwoods are generally better for steam beding; part of the reason for this is that they have fewer knots, but the wood is also generally denser with longer fibres, which makes it less prone to snapping/fraying.

I’d still go with the glue lamination technique personally, as steam bending is messy and rather dangerous.

All I could find online about making laminated curves was this.

Kerf bending(as mentioned by MikeG is another possibility; if you know someone with a table saw, perhaps you could get them to make a series of crosswise cuts in your timber (say, 1/2 inch apart, but 3/4 of the way through the wood

Is this armature going to be visible/important at all in the finished sculpture? if the answer is no, then I’d do away with the idea of beding the wood altogether and merely jigsaw out some curved pieces of MDF and fit them together.

9

Hi there,

Yes, I’m trying to build a Japanese paper lantern sort of thing, using ramen as the covering. It’s sort of a translucent, parchment color when dry, so the armature will be visible, and an important aspect of the finished piece. This is why light colored, delicate looking wood is necessary.
I have access to a pretty decent array of woodworking tools through my university art department shop, but I don’t think we have a planer. Do you think a bandsaw would be okay to rip the wood? Keep in mind that I have little or no woodworking experience whatsoever, heh.

Thanks,
~mixie

10

Here’s my idea.

I will describe the project like a globe. You are going to make wooden “bars” for the lines of longitude. Similarly, you will construct a single hoop-like bar for the equator. The poles will be made in the fashion of those circular pieces from Tinkertoys.

You will need a piece of 3/4" MDF, or similar, cheap panel stock.
Cut the desired radius on the panel stock as a full circle, marking the diameter with a pencil line.

Rip the pine into very small, thin strips, no more than 1/16" thick. You’ll lose a lot due to saw-kerf, so wider stock is desirable. The pine must be knot free, and in fact, defect free. You will now have numerous strips 1/16" by 3/4".

Wax the living daylights out of your MDF form. The wax will act as a release agent. The glue will not stick to the form.

Glue six or eight strips, face to face, and staple them, as a sandwich, to the form. For practical purposes, you may only be able to do three or so at a time. Leave them there until the glue dries. When the glue has dried, you can pull the staples out. Repeat until desired thickness is achieved. (Eight sixteenths, or half an inch.)

Do not remove the “bar” from the form until you have transferred your diameter line from the form. (Very important)

If you want the bars thinner than 3/4" they can be cleaned up a bit and ripped. (Advanced technique. Get someone to do it for you who KNOWS how to use the tablesaw!)

You now have your longitude lines.

The equator is much the same, only you use the whole disc of the form. Stagger the joints, so no two line up. This is called “bricklaying the joints”. (The lines don’t line up. Just like a brick wall. Get it?)

To make the North and South poles, use the lathe.
A small block of wood must be mounted to the faceplate, and turned to the spherical shape.

Contrive some means of joinery for the longitude bars to go into the North and South poles. Similarly, you must join the longitude bars to the equator.
The disk form for the equator will have radial lines on it, which you will transfer to the equator before removing it. This will orient the longitude bars vis-à-vis position on the equator. Maybe you could make your equator slightly smaller to facilitate joining the pieces.

There’s a lot more to this process than I can type.
With any luck, I’ve given you a good departure point.

Here is an example of wood laminated to a form. I used clamps. If you’re smart, for your project, you’ll use staples. Stapling laminae like this is a boatbuilders technique called “cold molding”.

On preview I thought of one more thing. Your circular disk should be in two or three pieces. It will be easier to get the hoop off by breaking up the circle from the inside.

Good Luck

11

And you’re going to have to change states before you can do this too.
:wink:
Building a sphere is advanced and difficult.
<grumble grumble>

12

A wood sphere sounds difficult. Are you sure you couldn’t use a balloon, maybe covered with rice paper or something similar to make it attractive?

If all you need is wood hoops, it’s not quite as difficult, although still non trivial.

13

Well, okay. I don’t need a whole sphere–I just need a spherical armature. I’m building a ramen-lantern. My idea was five wooden hoops, one large one, two medium sized, and two small, making up lattitudes. Attach them somehow, possibly with two or four longitudes, but maybe with straight bars as the curves may stick out past the noodles which would not be pretty. Copper wire might work for this, or some sort of white (coated?) wire, if it exists. I want the longitudes to be much less conspicuous than the latitudes, if at all possible. It needs to be open at the top for the light fixture. The noodles will be draped/hung/something in such a way as to create a mostly solid skin, which will be translucent when dry. It’s a light fixture–so the smallest amount of armature I can get away with is ideal.
I can’t use a balloon for several reasons. 1. It’s a cheap cop-out. 2. At some point it will pop and destroy the very delicate ramen noodles. 3. No way to add the light fixture. 4. Not spherical. Etc.

And forbin… wow. You don’t happen to be anywhere near Davis, and feel the need to intern for little or no pay as an armature-builder, do you? :wink:

Peace,
~mixie

14

My niece attends the Univ. there, that’s about it.

Latitudes are different sized. Harder.

Longitudes are all the same.Easier.

15

Why not cut the circular pieces out of Japanese plywood?

16

Here’s a little more detail; what I would do (in keeping with the Japanese theme) is to go to a place that sells imported Japanese motorcycles and ask them for a few bits of plywood from an old packing case, then (carefully) fret out four pieces like this and a bunch of different-sized circles, each of them essentially like this, then assemble it into this.

You could make eight of the half-circle pieces, in which case you need slots at the diagonal positions on the circular pieces, as well as those at the cardinal points.

17

WOW Mangetout!! You really have an interest in Wood don’t you? I wish I found this thread earlier. I have been building a wood working shop in my barn for the past five years, I almost have everything we want. My latest prject was with Mrs. Phlosphr and we built a medieval long bow… We had a blast!!

Good luck Mixie!!

18

Bending wood is not as difficult as everybody is making it out to be.

The first thing you need to do is to soak the wood in water. The next thing you do is take an iron and soak a towel in water. Place the towel on the wood and put the iron on the towel. When the wood is hot and steam emitting from the wood start to bend it into the shape you want. Depending on the board thickness this might require some mechanical help. Bend the piece slowly meaning don’t try to overbend it. Secure the peice in the position that you would like for it to be and let it cool for a couple of hours. When you come back and release it it will be bent. Remember wood will act like a spring it will spring back so you will have to overbend to compensate for the springback of the wood.

I have done this many many times with wood as thick as 2 inches.

19

Yet another suggestion/approach… If this is to be a Japanese style lantern sculpture thingie, why not try using rattan or bamboo strips to assemble the frame. You should be able to find the raw materials cheaply at a garden center (the stakes used to support plants). Splitting the stakes is fairly easy with a good sharp chisel or sturdy knife (but ALWAYS cut away from your self - trust me on this one). Then soak/steam the strips and bend to the desired shapes. If you have a large enough scrap of plywood, make a simple jig to hold the bent pieces by hammering a bunch of finishing nails in circles the sizes required. Use finishing nails so that the completed hoop can be removed without catching on the nail heads. You can glue the overlapped ends, for extra strength bind the joints with thin cord or thread and then apply more glue to this. The resulting hoops should be sturdy and light and also have a more organic look than squared-off pine might.

20

It’s not difficult. But getting the shape right (e.g. perfect circular rather than elliptical or asymetrical) is not necessarily easy, especially give the “springback” problem. And joining the ends means either using a butt joint (not very strong) or a scarf joint which I, at least, have always had trouble doing accurately.