Tuesday, May 11, 2010

Passionate Necking Session

This morning I cut a number of neck shafts and blocks. Complementary angles are fashioned on both parts. The neck material here is Spanish cedar and the block is alder.

I've made up a load of jigs to make this operation less of a head-scratcher. Some luthiers lavish attention on their jigs, making them of precious materials. I'm not one of those. They're a little on the ugly side, but they work to keep things consistent.

Here I'm marking the joining surface of one of the blocks using this template that has the forward angle built in. There's a matching jig for the neck side of the joint. There will always be a little fussing to get things mated up perfectly, but this gives me a concrete guideline to work from.

Little notches on the template surface show the joint positions between each rib. I originally envisioned using these jigs with a router to machine the appropriate ends. I decided that besides being noisy and dusty, it wasn't that much faster than cutting things by hand.

Here's the neck blank marked up in similar fashion. The profile is a segment of a circle.

I've extended lines between top block and nut head surfaces.

Making shavings on the shooting board. Spanish cedar is special stuff! Historical lutes often have spruce or poplar neck shafts under the veneer. I like the cedar because it's very strong, stable and light. It also has the most wonderful spicy cigar-box aroma. The scent lingers in the shop like incense. It's easy to plane, but contains tiny sandy grains of crystallized resin so I'll need to sharpen the blade when I'm done.

I'm tapering the blank in thickness down to the lines fore and aft.

And there we have it. All squared up. Lots of potpourri too.

I've drawn some angles to denote the bulk of material to be removed. This is done with a block plane. I suppose one might use a spokeshave for this, but the short registration surface makes it more difficult to maintain good straight lines. I'll retract the blade and take smaller shavings to get down to the finished profile.

That's close enough! You can see the little fixture I made to hold the blanks off the bench. It also helps when the time comes to glue on the veneer. It's countersunk from below for two screws that just barely protrude. These hold the blank in place.

The surface is refined using a mill file. This perfects the profile at each end and smooths out the plane tracks. I'll follow this up with a "shoeshine" using 150 grit garnet paper.

This neck is destined for an all-white lute mimicking the ivory instruments reserved for Renaissance royalty. Rather than subject an elephant to the indignity of tuskless living, I've decided to use American holly, the whitest of woods. This lute will have an all-black sister made with ebony. I'm scraping down to 1.2mm.

A template eliminates the guesswork. After cutting the veneer to size, I'll bend it using my electric iron. It's almost supple enough to go around the neck by itself, but as soon as the glue hits it, it'll want to curl up in the opposite direction as the fibres on the wet side swell. Pre-bending will counteract that.

A generous coat of glue.

Surgical tubing makes an excellent clamp. It provides even pressure over the entire gluing area. I'll let this sit overnight and trim off the excess tomorrow.

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