Friday, July 12, 2013

Making a neck blank

I’ve started work on Adrian’s double commission- a tenor mandola and an octave mandolin. I’ve just made the neck blanks and thought that you might be interested in how I made them. As Adrian wants the instruments to match, I’m making the various components out of the same pieces of wood.
For the necks, I started with a very nice piece of quarter sawn sapele. Now, if I were a factory, I’d bandsaw the profile out and job done! However, that’s not how I do it! By-the-way this procedure is the same for all of my instruments.
After some initial marking out I use my band saw to make the first cuts. Although my band saw is relatively small, once set up properly, it will cut 80mm thick hardwood.
Once the first cuts have been made, I mark out and cut the head joint. I always use a scarf joint at the head;  it is vastly superior in strength to any other method of producing the angle at the head as you do not end up with short grain across any part of the head/neck juncture.
At this point I also reduce the thickness of the head to about 13mm- close to its finished depth.
Before the head is glued on to the neck, I cut the neck, in two, along its length. If ever you have cut a piece of wood along its length, you will know that the two individual pieces can move relative to each other as internal stresses are relieved. I also take this opportunity to laminate the neck with some contrasting veneers. By relieving any stresses in the wood and then laminating with veneers you get a very stable neck.
 Once glued back together the blanks are trued up by hand to get them flat and square.
The back surface of the neck can’t be planed as the heel would get in the way. So here I use a Wagner Safe-T planer to flatten and thickness the neck. This tool is like a fly cutter for wood and is a bit scary to use, but works extremely well.

You can see the cut that it makes. Also you can now see the laminates of the neck; I’ve used thin black and thick white maple veneers as this will echo the binding around the front of the instrument.
The scarf joint is then carefully prepared; I said that this joint is vastly superior- the caveat being that it is done well!
When the two pieces of the scarf joint are glued together, they must be clamped down firmly to a work board. When you apply pressure to a scarf joint, as the clamping force isn’t perpendicular to the joint there is a tendency for the joint to want to slide apart.
 Once the head is on, wings are glued on to increase the width of the head for the tuners. Hopefully you can see why luthier built instruments should be superior!
Truss rods next……………….



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