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I wrote an informational article about how wood is bent for acoustic guitar sides and falcate braces. It's pretty long so I'm not going to post it in it's entirety here. The short version is that steam is really cool. We can bend wood by using only a soaked piece of wood and clamps but it has to be a thin piece. A guitar side is bent using a heating pad and water to create steam at close contact then apply pressure at the middle,upper and lower bout the conform the side to a jig. My theory is that steam lubricates the fibers of the wood to make them slip next to each other. This doesn't cover using a steam box or bending iron. Check out the guitar bending article.

Hi Max,
For most of us the article is a "coals to Newcastle" thing, but I did see an idea I haven't seen before - It appears your father has made an adjustable waist caul for his bending machine. For those who make a number of different guitar shapes it might come in handy.

Clay- Had to look up "coals to Newcastle". That's a good one. Pretty much applies here. Says it was well known in the 1500's. How old are you anyway!--Bob

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Clay, I think Charles has been using an adjustable waist caul for quite a while. I have pictures of his bending seminar at the 2008 GAL conference and his bender has a stacked caul.

"How old are you anyway!--Bob"

Who knows? - but I'm in my sixth decade of this avatar

Freeman wrote:
"Clay, I think Charles has been using an adjustable waist caul for quite a while. I have pictures of his bending seminar at the 2008 GAL conference and his bender has a stacked caul."

Charles Fox? I could certainly believe that. Perhaps that is where Jay got the idea, and now I have gotten the idea from seeing Max's post. That's the beauty of the world wide web.

AFAIK Charles Fox "invented" the bender that most of us use today. I've always heard them called "Fox benders", I bought mine years ago from John Hall and have bent literally two dozen sides (and wood bindings) on it. In 2008 Charles gave a demo at the GAL conference, he was on a new version by then that made it a little easier to load and to do more complex bends like cutaways. I also remember him breaking a mahogany side, and his comments - I felt a whole lot better. At that time his bender had a waist with a number of slats that could be adjusted to fit the particular guitar and then locked in place during the bend.

I have a habit of each time I make a new shape I cut out a set of plywood or MDF shapes - the "outies" become the building mold, the "innies" the bending mold for the Fox machine.

As with many others here, I both use the Fox machine and I still bend over the pipe. Particularly if I have one small bend to make (maybe a patch for a repair or the horn on a cutaway or binding for a head) I just go to the pipe. When I saw your earlier quote I was going to say that I heat my pipe with coal......

I have blue prints for Charles' bender and it shows the adjustable caul, that's the way I built mine many moons ago.

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Jim Watts
http://jameswattsguitars.com

Clay- So you're just a kid! Thought so.--Bob

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“ The meaning of life is to find your gift and the purpose of life is to give it away” Pablo Picasso

Typing on an iPhone while travelling, I’ve already lost two drafts, so this attempt will be short.

Your article is quite badly flawed and exposes your lack of plant physiology, anatomy, wood chemistry and wood engineering. I suggest removing your article and doing some homework. Bruce Hoadley’s book would be a good place to start and should be on every serious woodworker’s shelf.

From there, you want to understand the crystalline nature of cellulose and the thermoplastic nature of its chemical bonds. As you’ve noticed, a piece of wood bent while wet will generally not hold its shape unless heat is applied to weaken the bonds of the cellulose molecules that reform when the crystal cools, allowing the bent wood to hold its shape.

Don’t want to discourage you, but some research is required before you write internet articles.


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Thank you for the feedback everyone.

One of the first things I used for bending was a cannon shell with a propane torch stuck in the end. Arthur Overholtzer was building an electric bender, but it was rather expensive and only bent one type of side per model. Charles Hoffman shows them on his website, and I assume still uses them.They were electrically heated, so were like a mold and blanket in one.
Several years later I saw people using what I believe was an early type Fox bender- it used metal slats and light bulbs for heat. It looked a little involved to build and the cannon shell still worked fine. But still his design made a side bending jig much more accessible and affordable for the average amateur luthier. And it has evolved over the years.
When people started using heat blankets that seemed like the hot setup. I could make a block form and an assembly mold from the same material. Using the block form, a blanket, a kerf kore caul, and clamps, I bent sides more easily than using the shell and torch. I think many people modified their Fox benders to use blankets instead of light bulbs.
I can see some advantages to making a "holder" for the block forms - not exactly a fox bender, but incorporating some elements of that design, but still allow me to add extra clamps for when I am laminating sides. I may yet do that.

"Clay- So you're just a kid! Thought so.--Bob"

Yes, but when I get up in the morning I feel like an old sole - not the old soul that is wise beyond their years - the old sole you find on a pair of worn out boots that have been stomped on and dragged through the mud and feedlot.

Max—

What I am about to say may come off as harsh, but please take it as my attempt to be helpful.

First, I agree with Tim Mullin's comments.

Moreover, the article contains a lot of flawed writing. By that I mean: It contains many poorly constructed sentences; many misspellings; and lots of bad grammar. Now, understand that I let that stuff slide in an Internet forum conversation. There are very smart folks (some here on the OLF) who demonstrate in their written conversations that they do not write well. But if you are going to purport to write and publish an instructional article on your website, you really ought to get someone to proofread/edit your work first. I can get past bad writing in some contexts, but if you are trying to teach me something scientific in nature, then you need to show me, at a minimum, that you understand the basics of written English. Otherwise, I will get the sense (based on your bad writing) that you are not a reliable source of information. Harsh but nonetheless true.

Moving beyond the bad writing, there is a substantive flaw (even if I agreed with how you view what is going on when wood bends, which I don’t) in how you distinguish between the two bending methods your article describes. Several times in the article, you describe one method as using water and heat, and the other method as using just water. But when you explain how the “just water” method is done, you talk about putting the wood into a 350F oven. Well, that means both methods use heat and water. I honestly can’t understand how anybody could not catch this big of a logical flaw in their own written work.

Finally, let me pile on what Tim said. I will be super blunt, because you need to hear this: If you write a whole article about how wood bends, and not once do you mention a substance in the wood called lignin, then it is painfully obvious that you just don’t know what you are talking about. You might be good at making wood bend, but you don’t understand the science of it, based on the content of your article. You don’t need to understand the science of it in order to bend wood; you can just describe what methods work. But if you are going to try to talk about the science of what is going on when wood bends, then you need to go learn the science yourself first. Google lignin and bending wood. Half an hour on the Internet will teach you how wrong your article is regarding the science of what happens when wood bends.

Sorry if this feels harsh. I mean to help, not hurt. But helping in this context means letting you know when you are hurting yourself. Putting a bunch of gobbledygook on your website, stuff that is poorly written and obviously wrong, has great potential to harm your business. So, I recommend that you cut back on the gobbledygook.

I remember a time I was asked to fill in (on the fly) for an adjunct resource person who taught in the local school system. The subject was Taxonomy. Being fresh from University I was "down with it". I launched in to an explanation of species, genus, family, order,class, phylum, etc,etc, using all the scientific terminology I had gained as a zoology major. After about 15 minutes the audience's eyes appeared to glaze over - I guess it was too much for second and third graders.

Don Parker wrote:
"But when you explain how the “just water” method is done, you talk about putting the wood into a 350F oven. Well, that means both methods use heat and water. I honestly can’t understand how anybody could not catch this big of a logical flaw in their own written work."

Although I find Max's writing to be a bit "choppy" I do think he conveys to the average person two methods of - bending - wood. One using moisture and heat and one using water alone. Jay - bends - his braces by soaking them in water and clamping them around the form. After they are - bent - he then dries them in the oven and "sets" the shape of the braces. Being a Lawyer, I am surprised you misapprehend what he has written.
I agree there are some linguistic faux pas in the writing, and perhaps a less than perfect understanding of the process, but I think the information conveyed is essentially correct.

P.S. I have bent sides over a form using water and clamps . It is a tedious and time consuming process and not worth repeating, but it can be done.

Clay--

You and I will just have to disagree about whether I misapprehend what Max wrote in his article. I don't think I did. I think I read it carefully enough to understand what words are there, and what words are not there.

If you are going to differentiate one bending method from a different bending method, and the differentiating factor that you set out is that one method uses heat, and the other does not, then there should not be any heat involved in the method where you say there is no heat involved. The "just water" approach described in the article culminates in baking the wood (clamped against forms) in a 350F oven. That is not a "no heat" method of bending wood.

Maybe we should agree on some terminology. If by "bending," you include the act of flexing the wood with pressure, then letting it go back to something close to straight when you release the pressure, I don't find that to be a very useful definition of "bending" when we are talking about making guitar sides. I think a better term for that kind of "bending" is "flexing." When we are talking about ways of making guitar sides, I think we should limit our definition of "bending" to methods that result in a curved shape without the aid of any pressure to keep the wood in that curved shape. "Flexing" is useful (I make laminated purfling by "flexing" and gluing the veneer strips together, rather than "bending" the strips), but it's different from "bending."

Can you get some "bending" (limited to my narrower definition) to happen with just water and clamping against a form? Sure. As you said, it takes time, and depending on the wood species and how dry it is, it has limits. But that is definitely not the process described by Max in his article. He describes getting the wood wet, clamping it to forms, and baking it in an oven. That's not a "just water" bending method. Maybe if he had left the wood out to dry for a while, we could call it that. But the baking at 350F means he is not just using water; he is using water and heat.

I realize all of this makes it clear that I am a curmudgeon. Excuse me a moment; I need to go yell at some kids who are on my lawn . . .

The feedback is helpful and changes will be made to the article that reflect it.

Hi Brad,
I realize it is a semantic argument, and depends on one's view of who the article is written for. Lutherie, like the legal profession, uses jargon whose meanings may be somewhat esoteric to the average layman. When we say we "bent" a set of sides it is understood by other luthiers that we formed them into a shape suitable for using as ribs for a guitar. This is probably not the case for most people. When Max says the brace stock is bent around the form, using water but no heat, it means it was bent around the form using water but no heat- i.e.
bend1
/bend/
verb
shape or force (something straight) into a curve or angle.
e.g. "the rising wind bent the long grass"
The drying (and arguably "setting the bend") in the oven is a separate act. It is not necessary for the bending of the wood, only for it to retain that shape.
Anyway, try not to get bent about it, and be careful about the "yelling at the kids on the lawn" thing. Kids have been a long standing group for curmudgeons to hate and you might get called out on it.

Brad who? Don is the one yelling at kids on the lawn....

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Gosh, the list of those at whom I must yell is getting so long, I'm exhausted . . .

Clay--

By your logic, we can add a third way to "bend" that Max should have added to his article: put your hands on opposite ends of the thinned board (like when you are showing someone how big your most recent caught fish was), and push. But that wouldn't make any sense, because Max wasn't writing an article about how to "flex" wood that will spring back to being straight when you stop pushing; he was writing an article about how to make wood stay bent when it is not attached to anything or being pushed.

But, you should read the article the way you think it should be read. We should probably stop debating what it meant, for the good of the order.

Sorry Brad (to all Brad's) my bad.
I agree Don, 'nuff said. No ill will intended.

The fact that there is a debate over what the article has to say shows that the writing leaves something to be desired.

Max - I'm wondering what your intention was for your original post above. It wasn't in response to someone here asking about bending wood so were you looking for feedback on the article you wrote? If not, I agree with Clay's comment that it seems like a coals to Newcastle thing. If you were wanting to share specific methods that you use for bending wood, there is a section of this forum called "Fixture, Video and Picture Tutorials" that might be a better fit.



Clay - It occurred to me that there is a city on the east side of Seattle not far from where I am that's named Newcastle. It then occurred to me that it has a history of coal mining associated with it and furthermore, the main street through the city is even named Coal Creek Parkway. So I looked it up and the city is actually named after Newcastle on Tyne. So now I have even more reason to make use of that excellent expression.

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Bending wood is an interesting topic I have perused for years building Windsor chairs and other projects. But anyone who wants to understand it must look into how wooden wheels were made in the 1800s.
Someone here pointed me to video made at a Museum demonstration of old machine bending a 12 foot piece, 6 thick, of white oak. It was steamed in a container for many hours; then placed in machine. Then bent into a wheel rim in 15-20 sec by this steam driven monster.
Fun to watch