"crack repairs" do it yourself style. Never let anyone pin your cracks!.
Pinning cracks was a common technique used to repair cracks until the late 70s. A lack of understanding and good glue seemed to make it a good choice. Luckily, modern glues and a better comprehension made this technique obsolete.
Cracks are usually just on the surface, although some might go through tone holes. The cause of cracks is that the inside of the instrument has swollen quicker than the outside. Drilling big and ugly holes through the wood and trying to press it back together is a hopeless undertaking and causes only to build up more tension. We have seen many pinned instruments develop huge cracks on the opposite side.
Cracks should just be cleaned, glued and polished. If a crack goes through a tone hole, it needs to be replaced. We have repaired and exchanged thousands of tone holes and never had a single complaint of a crack occurring afterwards on the opposite side.
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