warped mandolin top

[john goodhind]

Hi everyone. I just joined this forum to see if anyone can advise on this: I've just scored an old Ibanez mandolin, which has a lovely rich sound, but the top is warped around the sound hole, causing a high action and some buzzing. I've attached some pics: I've put a straight edge across the warp for reference. As you can see, the top is pulling the fingerboard down. My question is can this be fixed by applying some heat and reinforcing the underside of the top around the sound hole, or will I have to take the top off? Hope you can help
John

[Mark Swanson]

Welcome to the MIMForum, John.

As you can see, the top is pulling the fingerboard down.

To help you think a little more clearly of the cause of the problem, the top is not pulling the fingerboard down- it's more the other way around. The string tension is pulling the neck up, and twisting the neck block. That forces the end of the neck near the soundhole down and has changed the neck angle, which makes the action very high. In short this mandolin is losing the battle with string tension.

[Michael Lewis]

As an educational experience you might put a new top on the mandolin. It would require "open mandolin surgery", in that it would need the fingerboard to be removed so the old top could be removed and replaced.

The idea of putting a sound hole directly in the path of stress is architecturally a poor one, though it has been made to work. If replacing the top I suggest something other than the traditional sound hole under the strings. Traditional 'f' holes are a better idea in this regard, and would allow longitudinal bracing. Just a thought.

[john goodhind]

Thanks for the feedback- I'm game to try a top replacement, as it didn't cost me that much. I've read on 'Mandolin Hospital Triage' that to remove the top requires sawing through the fingerboard at the 10th fret- I assume this will require a new fingerboard? Excuse my ignorance- I'm a novice at this!

[Mark Swanson]

Don't do that, just remove the entire fingerboard. You'd be re-fretting it too, so remove the frets first and put two small brads at each end of the fingerboard through a fret slot and into the neck wood. This will allow you to use them as location anchors when you put the fingerboard back on. If you don't want to re-fret, then you can drill two small holes through the fingerboard but you'd have to fill them then.

[john goodhind]

Thanks Mark.

[Michael Lewis]

If the fingerboard will come off without too much difficulty then removal is the way to go. Otherwise it might be best to get another fingerboard, and plane off the one that is there. The reason I mention this is that the neck can be damaged in the fingerboard removal process. See how it goes and proceed accordingly.

[Arnt Rian]

The idea of putting a sound hole directly in the path of stress is architecturally a poor one, though it has been made to work. If replacing the top I suggest something other than the traditional sound hole under the strings. Traditional 'f' holes are a better idea in this regard, and would allow longitudinal bracing. Just a thought.

Michael is correct about "...a sound hole directly in the path of stress..." being a bit challenging structurally, yet it is probably the most common place for it on plucked string instruments. Putting elsewhere might make the instrument inherently stronger, but it also has an impact on its tone, which you may or may not like. "The Mandolin Project", a book by Graham McDonald, has plans for various types of mandolins, and IIRC including a flat top with a sound hole under the strings, like yours. I believe it has a pair of slightly angled longitudinal braces ("tone bars"), one on each side of the sound hole, and maybe also another brace across these, above the soundhole. I've never tried this configuration, but it should have the potential for making up for lost strength with a soundhole under the strings. Whatever you decide to do, a good book such as this one, is recommended if you decide to make a new top.

[john goodhind]

Thanks everyone for your feedback. I've seen several methods of removing the fingerboard- all involve heat of some kind, some steam, some hot knives, some planing it off. I guess it often depends on what glue was used? Which method do you think will be the lead risky?

[Michael Lewis]

Oriental import instruments usually have some sort of strong glue that doesn't respond much to heat. There are often exceptions to any 'rule' that gets established. I would try heat from a clothes iron directly on the fingerboard. It might help to first remove the frets. You are going to get quite an education with this project if you stay with it to completion.

[Clay Schaeffer]

Another possibility, since you are replacing the top, would be to saw and chisel the top away from the fingerboard extension, leaving the body and neck and fingerboard intact. The new top would be slipped in under the fingerboard extension. I replaced a damaged stick dulcimer top that way.

[john goodhind]

Thanks guys- I'm making a start this week-will keep you posted!