One very common problem with violin family instruments are wing cracks. They occur at the top of the bottom hole of the f’s, usually due to too much pressure on the top while cleaning. Often they are neglected for years, and by the time the decision is made to fix them properly it becomes a monumental task to clean out the dirt and coax the edges together. Once they are glued it becomes paramount to make sure they don’t open again. This simple repair takes the stress off the crack by replacing most of the wood in the crack area.
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First a counterpart of the outside is made with heat-softening dental compound backed with wood placed in a plastic bag so it won’t stick to the varnish.
The counterpart is clamped into place and a trough is made along the crack with a 5mm incannel gouge.
A scrap 5mm soundpost is split and glued into the trough and, after the glue dries, it is trimmed flush with the surrounding wood.
After this the crack is retouched, and, hopefully, it becomes invisible.