bending figured maple

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bending figured maple

Postby John Sonksen » Sun May 27, 2012 10:52 pm

Hi folks, new to the forum and new to guitar making. I've been working on a couple les paul DC's over the last few months and I've got a bit of a conundrum. I've set myself up for a difficult situation, where I've decided to wrap the outside of one of them with some flame maple. I've built myself a steam box, sanded some flame maple strips down to around 3/32" and made sure everything is working properly. Problem is no matter how long I leave the wood in the steam box I just can't get around the upper bouts at the cutaway's without the wood breaking. I have read that curly maple is a pain to bend, and I think I may have it too thick right now, but my concern was the thinner it was the easier it would break. And when I say break, it's breaking right along a chatoyance line, where the figure of the wood reflects differently.

I have been a woodworker for 16 years, but honestly this is my first foray into steam bending wood. I've never tried to wrap something around such a tight corner before and am fully okay with this being operator error, I'm just looking for tips or shortcuts to getting this figured out. I am okay with perhaps abandoning the use of flame maple for the sides of the guitar as it will get a pretty dark stain anyways, and I'm going to use a nice binding so it won't be plain by any means if I almost black it out.

Here's a pic: Image

The pieces on the side right now are there because, well it's a long story. The spaces between the wood have been filled, it's been smooth sanded and it should be all ready to go, but it's simply not a finishable surface. Any advice would be greatly appreciated!
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Re: bending figured maple

Postby TyDonald » Mon May 28, 2012 7:26 am

You might be over steaming it. When I bend figured maple I give it a quick spray before applying heat, bend a little then repeat.
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Re: bending figured maple

Postby Steve Senseney » Mon May 28, 2012 9:01 am

Flamed maple is difficult to bend without breaking.

You need to get a bending iron.

Steam bending is great for thick pieces of wood. On thin pieces of wood, you get a lot of warping if it is too wet.

Failure with bending is often in the tension portion of the wood, rather than compression. This means that if you can rig a band on the outside of a bend, and keep it in compression as you bend, it will not fail as easily.

Continue to thin the wood further, down to .060" or even less at the tight curves on your horns.

Bending figured maple is not always easy.
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Re: bending figured maple

Postby John Sonksen » Mon May 28, 2012 10:50 am

Steve Senseney wrote:Flamed maple is difficult to bend without breaking.

You need to get a bending iron.

Steam bending is great for thick pieces of wood. On thin pieces of wood, you get a lot of warping if it is too wet.

Failure with bending is often in the tension portion of the wood, rather than compression. This means that if you can rig a band on the outside of a bend, and keep it in compression as you bend, it will not fail as easily.

Continue to thin the wood further, down to .060" or even less at the tight curves on your horns.

Bending figured maple is not always easy.


Thanks for the feedback. Okay, if I get a bending iron what exactly do I need? I'm not planning on doing this a lot right off the bat so I wouldn't think I need the absolute best bending iron out there, and frankly I don't have a ton of money to spend on a tool that's likely to see a lot of dust over the next year or so. There are some violin type irons with a sort of kidney shaped iron, and some with just a cylinder. Which do you think would suit my needs better?

The wood failed completely on the outside of the bend as you predicted. If I were to get an iron what type of material would be best used to support the tension portion of the wood? Something flexible enough to bend with the wood, but stiff enough to not allow the wood to give. Sounds like metal?

Third, would it be sensible for me to perhaps just go with straight maple until I get a few bends under my belt? As this is my first ever build I'm getting a bit anxious to get it done and I'm less concerned about this wood being figured than I am it being structurally sound. The edge of the guitar is getting a near black stain.
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Re: bending figured maple

Postby Chris Reed » Mon May 28, 2012 5:05 pm

A metal pipe with a blowtorch pointing into it is the cheapest option. Requires some practice to work out what is too hot/not hot enough, so practice on scrap. I find that flicking a few drops of water on the pipe tells me most of what I need to know - if the drops don't dance, it's too cool, if they explode into steam immediately it's too hot. Don't hold the wood in one place to long, move it across the pipe an inch or two, concentrating on the spot where you want the bend. You'll feel when it starts to bend, but persuade it rather than force it.
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Re: bending figured maple

Postby Steve Senseney » Mon May 28, 2012 6:07 pm

My bending iron is a 4 inch piece of 1/4 inch walled pipe. It has a bar welded into the center so it can be clamped in my vise.

I heat it with a electric charcoal started. This needs to be bent and squeezed a little to place it inside of the pipe.

I use a harbor freight router speed control to control the amount of power it gets.

This all together probably totals about $50-60. Depending on how much scrap you have at home, you could do this for a better price.

I have used metal straps for backing strips, the kind that they use to bind loads of brick. I have used galvanized metal flashing.

With all of our special tools and gear, you have to remember that instrument makers were bending wood several hundred years ago, without Harbor Freight or Sears tools!
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Re: bending figured maple

Postby John Sonksen » Mon May 28, 2012 6:38 pm

full disclosure guys, my first attempt with wrapping this thing was using a metal pipe with a torch stuck in the end. Of course I didn't do to much research before I did it and started scorching my wood pretty fast, got discouraged and decided to build a steam box instead! Sounds like I was on the right track to begin with, and actually already have a couple of lengths of pipe to use. I've read today about how to gauge the pipe temp with the water and then set the length of flame to keep the temp of the pipe around 300 degrees. I think I'll refine my setup for pipe bending a bit, I've heard you want to make sure the tip is slightly higher than the rest of the torch to maintain flamage, (an issue I was having was the torch would conk out occasionally), and give it another shot.

Out of curiosity have either one of you tried using a leather belt as a compression piece? I saw a video of a guy using one to bend the c-bout of a violin and this seemed like a good solution as it's pretty durned flexible. I'm also wondering if I should actually build a form for the sides like you would for an acoustic or a hollow body? I was kind of hoping to skip this step and look to just overbend the two pieces at the bouts and waist, the wood should be thin enough to bend around the rest of the body after these turns without being pre-bent.

Thank you so much, I wish I would have signed up for this forum sooner!
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Re: bending figured maple

Postby Steve Senseney » Mon May 28, 2012 10:43 pm

I have made cauls or inside and out side forms. I have not used leather as a backing material.

Out side forms are probably not as useful, as individual places where you need to put additional pressure as you glue your strip in place.
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Re: bending figured maple

Postby Rodger Knox » Tue May 29, 2012 2:17 pm

For what you're doing, the easiest way would be to use a regular clothes iron to heat the outside of the veneer (I'd take it down to 1/16") as you're wrapping it around the body.
That applies heat at the same place as the bending stress and also provides some support. A spritz of water might help, but it will probably bend OK dry if it's thin enough.
A man hears what he wants to hear, and disreguards the rest. Paul Simon
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Re: bending figured maple

Postby John Sonksen » Tue May 29, 2012 2:46 pm

Rodger Knox wrote:For what you're doing, the easiest way would be to use a regular clothes iron to heat the outside of the veneer (I'd take it down to 1/16") as you're wrapping it around the body.
That applies heat at the same place as the bending stress and also provides some support. A spritz of water might help, but it will probably bend OK dry if it's thin enough.

Not a bad idea Rodger. I think I'll have to pick up a new iron though, a Teflon coating would be good as my old 40's steel based iron has a tendency to stain when I use it directly on wood. What temp, permanent press?

JK, I'll expirament lol
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Re: bending figured maple

Postby John Sonksen » Tue May 29, 2012 3:13 pm

Experiment, don't know what happened there
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Re: bending figured maple

Postby Rodger Knox » Wed May 30, 2012 12:09 pm

About 3/4 of full works for me on most wood with most irons, some bends at lower temps, some take more. I've got a couple of old irons my wife has discarded and a small hobby iron for shrinking the covering of R/C model airplanes. The hobby iron works great for binding. The biggest advantage to me is you really get the "feel" of the wood getting hot enough and going plastic when you're applying both the heat and bending force by hand.
A man hears what he wants to hear, and disreguards the rest. Paul Simon
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Re: bending figured maple

Postby John Sonksen » Sat Jun 02, 2012 10:54 pm

gave it another go today, got one side done.

Image

I have to say, I don't think I picked an easy wood to start with here, though I've never been one to pick the easy way. I tried using a clothing iron, didn't work. Built a bending iron with a propane torch and aluminum pipes. Tried using aluminum flashing, didn't help. What did help was thinning the wood way down at the tightest part of the bend and taking plenty of time. So, I got one piece to work all of the rest broke. It seems like bending flame maple is about 80% luck, 15% patience and 5% actual skill and knowledge.

I learned some very important things today though that don't give me any more insight into how to make this process easier. The wood always breaks along the line of figure, this is where the wood changes density. The phloem layers in the wood itself drive the steam tangentially through the wood, which means the steam generated at the spot where the wood is contacting the iron, (I was using one pipe that was 3/4 OD, nested inside a piece that is 1 1/4 OD) exits the top face of the wood at a location diagonal from the point of contact. This to me seems to make it so the part of the wood that is being softened is not necessarily supported by the bending iron. It's only off by a little bit, but I think this makes a difference.

I have to say I think it will be a long time before I try bending flame maple again. I'll get some practice with some easier varieties and maybe try it again in ten years, lol.
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Re: bending figured maple

Postby Mark Swanson » Sun Jun 03, 2012 10:15 am

The first thing you should do is put away that bottle of Titebond III. It is not a good glue to use for instrument building, the best is Titebond I original interior glue.
    Mark Swanson, guitarist, MIMForum Staff
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Re: bending figured maple

Postby John Sonksen » Sun Jun 03, 2012 10:47 am

Mark Swanson wrote:The first thing you should do is put away that bottle of Titebond III. It is not a good glue to use for instrument building, the best is Titebond I original interior glue.

Don't worry Mark, I read a post about that. Titebond I is all I shall use from now on, that and hide glue.
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Re: bending figured maple

Postby Rodger Knox » Mon Jun 04, 2012 5:03 pm

How thin did you go? It's hard to tell in the photo, but it looks like closer to 1/8" than 1/16". Another factor that will cause breakage is runout.
My experience has been that 1/8" thick breaks most of the time, especially if there's much runout, and 1/16" thick only breaks if there's runout.
Of course I have to mention there are pieces of wood that will not bend, no matter what you do, but they are unusual.
A man hears what he wants to hear, and disreguards the rest. Paul Simon
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Re: bending figured maple

Postby John Sonksen » Mon Jun 04, 2012 5:40 pm

Rodger, the wood was right at 1/16 except near the apex of my bend. I found that by thinning it way down on the outside of this bend I got the flexibility I needed to wrap the bout. Of course I only managed to successfully make one side, the rest of my tries failed.

Can you further explain runout? I'm new to this bending stuff and this isn't a term I've come across in my field except when talking about spindles and arbors.
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Re: bending figured maple

Postby Steve Senseney » Mon Jun 04, 2012 7:13 pm

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Re: bending figured maple

Postby John Sonksen » Mon Jun 04, 2012 8:22 pm

Thanks Steve, that makes a whole lot of sense. I'd guess that given the way my wood was tending to break it had quite a bit of runout. It seemed to break at an angle of maybe 30 degrees, and since I didn't make my edge banding from a thick piece of wood I can only speculate as to what it truly was.(my edge banding was already about 1/8" thick, it was falloff from a cabinet job done long ago)

This is certainly very valuable information for me to use in the future so thank you to you and Rodger very much.
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Re: bending figured maple

Postby Barry Daniels » Tue Jun 05, 2012 8:52 am

Runout is not really relevant to curly maple because the curl is runout. A backing metal strip may be helpful.
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