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I've been practicing my hand bending and I've consistently been struggling to get a good bend on the waist without having some slight cracking happen. So far I've been practicing on scrap pieces trying to match the various curves so a catastrophic failure isn't the end of the world. But I'm poor so I can't constantly replace sides if they crack. The lower and upper bouts are not a problem just the hard bend at the waist like on an OM style body shape is where I'm struggling.

I've settled on using maple as a primary wood for the back and sides. Any tips? The iron I'm using is just the basic one that stewmac sells.

I haven't tried one yet, but I see people using a backing strap of flexible steel to support the sides while bending.

How thin are you making your sides?

Tip for bending on a pipe is to get the temperature right.

It has to be HOT! I have a spray bottle to test. Spray on the pipe and if the water doesn't sizzle and pop then it's not hot enough.

You have to heat a large area around the point that you want to bend so rocking or sliding the wood over the pipe heating up a large area first helps.

Start to apply pressure on the wood and once you feel it start to bend keep it going, don't stop and start all the time.

If you go to far it's easy to bend back.

At the waist you might want to bend it further then necessary as when you bend the bouts it tends to want to creep back.

Don't listen to music or have any noise going on in the shop. You need silence so that you can hear wood fibers breaking.

What jfmckenna said.......HOT, heat a large area...sliding back and forth, spritz bottle as wood dries out....patience is the key....as pressure is SLOWLY increased, feel the wood begin to succumb to the heat and pressure.......I always bend the waist first (ukuleles)....also, 'thin is in' when it comes to bending. I have one i bought years ago, probably LMI....have I cracked some wood, yes....curly koa takes a bit of patience and less water....I've heard some wood bends better dry...but I've only used mango and koa.....Bending wood can be a meditative experience...take your time. When mostly bent, I put them in a mold to hold the shape 'til I need 'em....

Dan--

Lord knows I'm no expert, but I prefer hand bending to machine bending, so let me offer a few things that might help.

1. As wbergman mentioned, a back strap can be really helpful if the wood has a tendency to break. I think StewMac sells something, but you can get it from other places. Wood (any material, really) bends by a combination of compressing the material on the concave side of the bend, and stretching the material on the convex side of the bend. The problem with wood is that it compresses pretty well, but it doesn't stretch very well. So, the wood breaks on the outside of the bend. Having a metal support across the whole of the bend, on the convex side, can help avoid the break.

2. Keep in mind that runout and "interesting" figure make sides harder to bend. Maple with interesting grain patterns can just separate at grain lines. I have a harder time bending maple than I do bending other woods like rosewood. So, just bear in mind that your chosen material can be bent, but can also be a challenge, depending on the grain. I particularly think a back strap is a good idea with maple. Violin family instrument makers use back straps on maple, I think.

3. Thickness matters. I bend at 0.085". You can go a little thinner for an easier bend, but then there is less to be sanded later. You can go a bit thicker, but then it is hard to bend without breaking. 0.085" hits a good compromise for me.

4. Heat and water: More heat, less water, is my preference for bending these days. I do not soak the sides; I just spritz the area to be bent right before I put it on the iron. And I use a pretty hot iron. I would go over 300F and see how you get along. I keep from scorching by paying attention. If the wood dries out, I stop, hold the bend progress so that it temporarily sets, then I spritz again and put it back on the iron. Too much water messes with the wood (maple can just separate with the addition of too much water), and too little heat just stresses the wood without softening the lignen enough to allow bending to happen.

I hope some of that is helpful.

Maple likes steam. Put a paper towel on the pipe and keep it wet with a spritz bottle. But if it's flatsawn then the water will cause it to cup. You can reduce it by using a wood block to mash it against the pipe. Cupping is a progressive problem, where part of the wood curls away from the pipe and cools down, so then you have the portion in contact with the pipe relaxing and taking the bend, while the out-of-contact part is being forced along for the ride, not relaxing but being flexed anyway. That causes it to cup farther away from the pipe, making the problem worse.

But even using the wood block, flatsawn maple still often cups beyond what can be sanded out. So then you have to try to do it dry, which usually scorches before it loosens up.

In other words, make sure your sides are quartersawn.

And if you really want to live the easy life, try straight grained quartersawn walnut. Every time I use it I wonder why I ever use anything else

I've done mainly violins and violas, tighter curves, but I bent the maple ribs on my arch top with a tight cutaway, and the little baroque I'm working on using the small violin iron. I only made mine about .075 or less and maybe .06 in the tight bends. Violins are about .04-.05. The poster I have of a Gofriller Cello has 4.75 tall ribs 1.3-1.8mms thick, so about the same as I made mine. Yeah, it's a cello not a guitar, but it's still around since 1693.

I'm not a religious rule follower.

They seem strong enough. I used smallish linings too. But I didn't cut into them for banding. The well flamed maple bent fine.

Get it hot. I just used my hands, the curves get in the way of the backing band. I did the cutout first with the band.

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Why be normal?

I thin down to about .088" I usually keep the temp around 290 and I spritz the wood without using a towel and such.

I think what you said about heating the area around the spot you want to bend is where I've been going wrong. I've been just using the small corner of the iron and trying to bend on that one single point. I think I'll try it on the larger area of the iron and see what happens, thanks for pointing that out!

Dennis on the cupping thing I usually tilt the wood on the sides to make sure the sides get heat along with the rest of the instrument. I'll try walnut some day I just have such a love affair with maple I'll feel like I'm cheating a bit lol

thanks for all the advice everyone else, I think that I just wasn't heating a large enough area before I applied pressure, I guess with my first guitar I just got lucky.

Dan--

Another thing to try is warming the side's bending location over the flattest part of the bending iron, getting it to start bending, get a larger section of the wood touching a lot of the iron, then moving that section of the side over to the tighter radiused part of the iron for more significant bending. It is easier to get heat to transfer to a larger area of wood if you are on the flattest part of the iron.

When you think about it, breaking is bound to happen if you are only heating a small part of the wood that is only touching the iron tangentially. That's why perfectly round pipes are not as easy to use as the purpose-built bending irons.

Good luck!

I'll give that a shot. Thanks Don!

I built a number of Shaker boxes 10 or 15 years ago. I have often wondered why guitar sides aren't treated like them:

https://www.youtube.com/watch?v=3j0ImrfyQPs

A little sanding and there is no evidence of the water bath

Ed

I used to build all cedar guitars using the boiling pan on the stove followed by a bake in the oven while tied to the form. It worked great; however rosewood and many other hardwoods and softwoods tend to ripple when bent this way.

I'm with Dennis. Give walnut a try and your love affair with maple will be sorely tested. As an added bonus, it's relatively cheap, too.

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George :-)

The tip several people have made above about taking advantage of the flatish side of the bendng iron to warm the wood and then slide it over the tighter radius part to make a bend is really effective.

I thickness the sides to 0.080" and for particularly tight bend areas like the tip of a Ventian cutaway I go down to about 0.075".

For water application, I spritz the area that's going to be bent right before going to the bending iron. Most of the time, I only spritz the side that goes against the iron. I re-spritz as the wood drys out. Some woods can benefit in the tight bends from a bit of additional spritzing on the outside surface. Based on my experience with curly koa and curly maple, I don't spritz curly woods on the outside of a bend since that can weaken the fibers at the tops of the curls which can lead to a crack.

Temperature: I have the standard bending iron sold by StewMac and LMI. For most woods, I have it set a 6 which corresponds to about 380 degrees. For woods that put up more resistance to bending, I set it at 6 1/2 which is about 420 degrees and keep the wood moving.

One thing that hasn't been mentioned is the orientation of the bending iron. I like having the pipe clamped to my bench top vertically. In that orientation, I'm looking down on the edge of the side against the pipe so the shape and progress of the bending is very easy to see. It also places the pipe closer to my head so it's easier to hear what's going on and it puts it at a good height and position to really lean into it if needed.

Another thing that hasn't been mentioned yet is pre-treating the wood with SuperSoft II or Windex to make it more receptive to bending. My experience is that it makes a significant difference.

One thing that works really well for me when doing the tight bends is shown in the photo below. Using two blocks positioned close together on either side of the location of the bend allows you to really concentrate the bending force in a small area and makes it easier to end up with tight bends. I use this method routinely and it helps a lot, for me. The pipe has to be firmly clamped to the bench because this approach can require a lot of pressure for some woods, but it works. It's also useful if it turns out that there is a weak spot right next to where a tight bend needs to go because you can isolate the bending action to just the area next to the weak spot so the side doesn't break. It also works for highly figured woods that don't want to make smooth bends but want to bend as facets instead. The flats of the facets can be made to bend this way.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Thanks for all that info! before my iron's heating element gave up I was actually having some really good success using a higher heat. One thing I just wasn't doing was heating a larger area of the side before I began a bend, I started doing that and had immediately better results. Once my iron is fixed I'll be trying a higher heat and applying your advice. I'd like to get better at the super figured stuff since I love it so much. Just a learning curve as with everything.