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Well, I was out in the shop tonight and came into my first cracked side, well, er, sides.

I building an OM with Imbyia sides and back, and well, that stuff is not the most friendly to bend, at least for me it wasn't

The first side is not even salvagable, cracked at the waist, not enough support I guess.

The second one.... well, I don't think it's salvagable, but maybe you folks can help me out.





This is on the inside of the waist.

If this one works out, I'm going to have to call on the Zootman to see if he has any lonly sides kicking around.

HELPPPPPPP!

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Rod,

Photos can be deceptive but those sides look to be on the thick side to me. Maybe you need them a bit thinner before bending.

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I hope you can fix this Rod, if you did like Michael Payne told me and make the sides flat again then flood the cracked area with CA and then rebend, maybe it would work?

Coach Michael?

Good tip on te masking tape there Rod, thanks!

Looks thick to me too .. imbuya has bent very well for me, I think its one of the easier ones to go.

Sides should be 85-90 thou, and they will bend like butter in the fox - little misting, supports both sides (I use spring steel, but the stainless slats are good for non cuts ) heat about 300.

Those might be salvagable, you never know till you glue it back with CA and see what you have after sanding flat again.

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Tony Karol
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The sides are miced at 0.092 which I thought was good for thickness. I use a heat blanket and spring steel. My bender may be the problem, although I've bent EIR and Flamed maple in it with success. I don't have a waist support like the Fox bender does, I tend to snug down the waist, bend the lower and upper bouts, than crank down the waist at the end. Heat.... well I don't have a thermometer so, I'm not sure, but there sure seems to be plenty of that. I have the heat blanket from John Hall and the rheostat and it is set quite high, water bounces off the slats before I start the bend. Oh, I did spritz it just a bit. I sure felt like I did everything right, especially on the second side after the first one cracked.

I have fear that when trying to bend it back to flat that the figuring will just crack the side apart. I'll give it a try though.

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Rod, spritz more than just a bit, especially if you use kraft paper, the wood will be kept in safer conditions IMVHO, I used just a little bit of water on EIR no 2 and had cracks so i used more on the second bend and it went well, hope this helps bro!

I really cant tell from the photos but the one you show looks more like what I call peal-up. Is this wood curly or quilted? I does not look like it has much figure but with high figure some times where the grain changes plane it will fracture easy. On these woods I preheat to temp (aprox 310*) then turn off the heat for a bout 5 min. then crank it back up to temp and bend. I bend the waist 80%, then the lower bout 100% , then the upper bout 100% taking time to feel the upper bout bend, not just pulling down the caul willy-nilly. Once both bouts are fully bent I finish the waist this pulls the remaining waist bend from the bouts and maks them good and tight. I have far less of this seperation this way.

One the one that broke at the waist without more info I am betting it had not go to temp or you cranked a bit to fast.

.080-090 is where I bend almost all sides .092 should not be the issue.MichaelP38930.3987962963

I've been thinking about this this morning and I would tend to agree with you Michael, I don't think I let the sides get up to temp enough. I would think that turning up the blanket is good for the blanket and the slats, they will come up to temperature really quick, but the sides will take longer I think.

Yes Michael, I think your right with the figure line as well, because both of the side cracked right along a figure line (that's at least what it looks like to me).

Dang it, well, I will try again, but I will be getting me a thermometer first and I should realy think about adding a waist support the the bending machine, like the Fox bender.

Oh Serge, the tape was there to hold my binding to the side while bending. The binding came out perfect though, no craking there. Mac Ebony.

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Rod I'll take a look see if I have a set of sides just in case those don' work out. The photo looks deceiving because thickness looks more like .110 or so.

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two things could be going on - like you say, if you bend too fast, then the side is not hot enough and it will split. You need the lower support, ie, under the waist, to bend - it holds the outer fibers against the slat - if the fibers arent allowed to move, then the side will bend, because it cant crack -not saying that the fox provides total support here, and the spring ahs give, but it sure helps. The other thing to watch is too much heat, and not enought moisture - the side will dry out if you bend to slow,then it gets brittle and cracks.

In my fox with imbuya at 90-95, I could bend it dry and be fine. Its all about knowing what your bender and blanket can do. That takes some trial and error (had a couple of those last year when I changed form a variac to a dimmer - too hot)

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Tony Karol
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"let my passion .. fulfill yours"

This is on the inside, right? And it does not go all the way through to the outside, right?

I don't see the cause for concern. CA it shut, sand it, and relocate your side braces so that one of them covers it up. (If you aren't using side braces, maybe this is a good opportunity to start.) Structurally, it will not go anywhere, particularly with a brace over it. Cosmetically, even if someone takes the time to look inside the guitar, the crack is covered by a brace. Am I missing something?

Kelby the cracks in the pics are out side of the bouts and I am guessing inside of the waist as this is typical that the cracks start on the outer surface of bends where the fibers are being stressed the most.

Michael, that's certainly a bigger issue if it is on the outside. But Rod's original post had a note below the pictures that said "This is on the inside of the waist." I didn't see any reference to the outside of the bouts. Perhaps I misunderstood, though.

Inside of the waist would be the outside of the waist bend meaning the outer surface from the radial center of that given bend. So yes the waist crack would be to the inside of the guitar but the outside of the waist bend My bad explination

I think I understand you, Michael.

Here's the bottom line for me. If you have a crack that will not be visible from the outside once the box is closed, then CA and a side brace to cover it will solve the problem. If you have a crack that will be visible from the outside of the guitar once the box is closed, then glue it up as best you can and hope the glue line won't be visible. If the glue line will be visible, then I picked up this tip from Benedetto's book: use those sides for a sunburst guitar, and make the sunburst dark enough in the area of the crack to cover the glue line.

I think the big issue is he cracked one of the side waists through, the side he shows in the picture is most certainly workable when carefully repaired.

Yes, the first side cracked at the waist from the inside as that is the tension bend to the outside, the compression side of the bend clean through.

The second side, pictured above has cracked at the waist on the inside, tension bend and there is very little hint of the crack on the outside, although I am afraid that bending it back straight will crack the outside face as well.

I've got Bob looking in the zoot shed for a set of sides, as the first is toast. I'll try and fix this one as it will be good to learn.

Thanks for the help guys. Tony, I think I will modify the bender and add the lower support at the waist. Michael, thanks for the heating schedule suggestion.

Just when you think you've got it right, Murphy comes along for a quick visit.

So Tony, you mention having enough moisture or the side will dryout, get brittle and crack, than you mention that you bend Imbuya dry and have no problems. That's the difference with 4 guitars built versus xxx (how ever many hundred) you've built.

I'm nervous about getting a second set of this stuff to try, but I'll try it again for sure.

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"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

Bending dry .. right - there is always some moisture in the wood, the trick (sorry) is to not overheat with too much temp. or go to slow as to dry out while getting it into shape. Almost any wood can become pliable without added moisture with heat alone. The moisture aids by taking the heat thru the wood, and by softening the fibres some. If you wrap in foil, it has no where to go - I bent a set of coco one time and when I got to the upper bout (bend waist first, then lower, it pretty much falls down by itself) the foil had ballooned out - it was air tight - I popped it and a whoosh of coco scented steam came out !!! So with the foil, a VERY light spritz is a lot is what I am trying to say.

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Tony Karol
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"let my passion .. fulfill yours"

I think i might try the foil instead of Kraft paper next time, good tip Tony!