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Warping of the Table
One of the commonest and most easily visible problems with mandolins, is a warped top. The reasons for this are largely to do with string pressure, when the head and tail are pulled towards each other. The top buckles as a result, usually around the sound hole, where the hole weakens the structure of the top. |
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This photo shows warping around the sound-hole caused by string pressure on the area weakened by the sound hole and inlay. |
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With the strings off, I use pads dipped in boiling water, against wooden cauls to try and correct the worst effects of the warping. |
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I then glue in a thin hole re-enforcement under the sound-hole to try and prevent further warping. |
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This picture shows a corrected warp, with the hole strengthener just visible beneath the top. |
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On another instrument, a mandriola, the damage was mostly to the sides of the sound hole, and again hot pads were able to reduce the distortion without removing the top. |
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In this photo, the hole re-enforcement is pictured before it is glued under the top. It should help the top resist the pressure of the 12 strings better. |
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On another instrument, with a detached top, it is possible to see the pads, which are folded pieces of cotton cloth. |
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Here the re-enforcement glued in place is visible due to the detched tops. |
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To prevent the warping from re-occurring, I often glue re-enforcements inside. Here is one braced against cauls while the glue sets. |
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A view of the same type of re-enforcement from inside, this time original to the instrument. |
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More recently, I have opted for this type of brace, stronger than
above right, and easier to fit, even with the top still on than
the full surround.
Braces are 2-3mm thick and 6-8mm tall. |
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