Removing Quilted Maple Top From Guitar?

[GuitarMaestro]

I currently build a guitar with a bookmatched 6mm quilted maple top. I glued the first half on and then started to bend the second one over the forearm contour. Usually I throw the area of the top that goes over the contour in hot/boiling water for 20 minutes and then clamp it in place and wait a week until it dries. Afterwards I glue it on. Unfortunately the top developed two several cm long cracks during drying. This never happened to me before. You cannot imagine how angry I am. The top cost 150$ and was absolutely unique and awesome.

Anyway my question:

How can I remove the half that's already glued on? I used LMII's instrument maker's glue which is not water-soluble but they claim it softens with heat. Would you try to get the top away with heat or simply plane it away? I would preffer to get it off without destroying it, as it could maybe be reused for a guitar with another shape....

Thanks in advance,

Marcel

P.s.: I never had that problem before. Any ideas why it might have happened?

[WezV]

the top will have swelled because of the water and shrunk as it dried out. it will have cracked as it shrunk.

It would have been better to use more heat and less water when bending the wood.

[fryovanni]

If the top has enough value to you, and you would like to have a better method for heating(to protect your future high value tops). I would recommend you pick up a heat blanket.MSC. I won't go into a long winded "why that happened", because I think you know why. A heat blanket will allow you to control and deliver enough heat to soften the glue, as well as bend when you need to. For what it is worth. I would recommend you pick up two 6" x 36"(cost is a little over $100) which would also allow you to use them for possible neck straightening(repair), acoustic side bending(if you ever choose to do so, same applies to semi-hollow, archtops etc...), as well as contours. Removing the top will take a bit of work, but take it slow and it can be done.

Peace,Rich

[Guitar WIll]

You could try looking into the articles for removing the fretboard off a neck. I would have thought that this would work, but more care would need to be taken becauee of its akward shape.

where did the cracks develop, because you could fill them using a mix of sawdust and glue. and then finish it in a burst with dark edges so that they cannot be seen.

[GuitarMaestro]

Thanks for the advice.

@fryovanni: Good tip, but I wouldn't have any other use for the blanket. Sp do you think it will be impossible to remove the top with a simple electric iron?

@WezV: So is "cooking" part of the top for 20 minutes a bad idea in general? It usually worked perfectly for me. Should I have put the whole top in hot water and not only part of it, so that it expands and shrinks the same everywhere? Or is it generally better to use an electric iron with steam function and not to put in water at all?

@Guitar WIll: Good idea. I already thought about trying to hide the cracks that way and if I dont succeed in removing the other half of the top without destroying it I will give it a try....

[WezV]

@WezV: So is "cooking" part of the top for 20 minutes a bad idea in general? It usually worked perfectly for me. Should I have put the whole top in hot water and not only part of it, so that it expands and shrinks the same everywhere? Or is it generally better to use an electric iron with steam function and not to put in water at all

i wouldnt cook any part of a guitar by boiling for 20 mins. Even if you do the whole top it will still be shrinking under the clamps which may still cause it too crack. generally excess water and wood dont work well together

I have removed plently of fretboards with an electric iron but never a top so cant say how well that would work.

It might work with an iron if the top is thin enough but i would use a bending iron. get a peice of long pipe and a blowtorch and bend the top in the appropriate place (thats the hard part). use water on the wood to stop it scorching, even soak the wood for a few minutes if its needed. Then bend it and clamp it in place like you have been doing.

Some people prefer to cut a kerf on the reverse of the top to get a sharper bend, again you need to be carefull about getting it in the right place

[fryovanni]

You may want to consider a small blanket that will at least deliver enough coverage to get your contours, and you could heat a good portion of the top at one time(I bet you could pick up a smaller blanket for $30-40. If you place the cost of the smaller blanket against the cost of saving this top and not ruining future tops then it is a pretty good investment. Just a suggestion.

Delivering heat is what you are trying to do here. Water(generally steam) is only a mechanism to help carry the heat because we generally have poor systems of delivery or the wood is way too thick. When you bring wood up to around 300 degrees give or take 10 degrees you soften the lignin. When the lignin is softened the wood fibers can be moved to a new position and when it cools it resets in that position(you can think of it like hide glue). That is for proper bending. As far as heating and softening glue. Titebond that is brought to about 150 degrees for a sustained period(they say "overnight") loses half its strength(according to Franklin), so I would assume it will breakdown rapidly in the 200 degree+ range. If you can deliver even heat across the board(not extreamly high temp) for a sustained period to allow it to penetrate through the top. Then the glue will release evenly and easily. If you can deliver heat to localized areas you will have some soften and some in tact which will make the process more stressful. A hot knife can help a lot as it can deliver the heat directly to the glue joint area(as soon as it gets in there), but it is a slower process(if you rush you will stress the wood and risk damage).

Peace, and best of luck!

Rich

[GuitarMaestro]

Thanks again for the answers!

Some people prefer to cut a kerf on the reverse of the top to get a sharper bend, again you need to be carefull about getting it in the right place

I already read about that in another thread and I think that's what I will try next time. Not a single kerf but a series of parallel kerfs to the underside of the top at the angle where the arm scarf will be bent. I really wonder why this is not recommended as "the" way to do it. This way you dont have to use much force/heat/water to bend the top and the wood is free of unwanted tensions afterwards.

@fryovanni: Thanks for that detalied post. Made me think about some things differently. Very informative!