A doubling reinforces the original button of an instrument. When a neck pulls out, or is broken out of an instrument, damage can occur in the button area . Wood fragments from the inside of the button may stay glued to the neck or as in the example photos, the entire button may remain stuck to the heel of the neckstock.
So simply regluing the neck “as is” simply doesn’t work since, as I’ve mentioned elsewhere previously, the button plays such an important role in insuring the strength of the neck insert and therefore the correct overall neck projection. Doubling the button reinforces the entire area while still retaining most of the original button. The button will show a joint which in most cases can be hidden by fitting an ebony crown. In this case I was doubling the button of a mandolin therefore an ebony crown is not necessary. This type of procedure is only really carried out on instruments worthy of such a long and tricky intervention. Such as this American Mandolin by American Luthier Claude Watson from the 1950’s
So the first part of the restoration of the broken button was to carefully remove it in one piece from the heel of the neck
Next having removed the back of the instrument a trapeze shaped dig out (half the thickness of the instruments back thickness must be carefully excavated
An equal amount, as the depth excavated from the instruments back, must be very carefully removed from the broken button itself also. Then after making a matching template a suitable piece of matching timber (in this case Maple) must be prepared for insertion.
Paper template with thinned down matching maple is prepared for insertion.
This instrument can now be closed up again and a new neck inserted now that our button has been grafted back into place.