Guitar #1, warts ‘n all…

[Colleen McTigue]

So I finally got around to working on the neck, specifically making the tenon, following Cumpiano’s new and improved design. The barrel bolts I’ve got are 10mm, so first I had to find a 10mm drill bit… harder than you’d think. Lee Valley was the only place that had one. Then when I went to use my drill press to drill the holes, I discovered it was too small - even with the stage at its lowest point, the heel block would not go under the bit, so I was forced to use a hand-held drill. Everything was going reasonably well, I thought, until I cut the first cheek and discovered that the bolt holes didn’t line up with the barrels. So off to the store to get a hardwood dowel, to fill and re-drill. So that part’s done.

[Alan Carruth]

Although putting the dowel nuts crosswise like that usually works, it can be a problem. When there is pressure on bolt it pulls the nut down against the end grain wood of the tenon. If the nut is not a very tight fit the pressure is concentrated along a line toward the nut, and there can be significant sideways pressure. If the nut is too tight, and the neck sustains a blow of some sort, it can split.

This happened to one of my students when we started using cross dowel nuts. He had bolted the neck on his guitar and when he picked it up from the bench he hit the head against a low beam on the ceiling. The heel split across at the upper nut and the body of the guitar fell to the floor. At least one other local maker has had that happen that I know of.

Since then I've been drilling the holes for the cross dowels on the center line of the neck, perpendicular to the fingerboard plane. That way, if as split gets started the assembly 'fails well'; the two halves are retained in the mortice and the neck can't fall off.

Hardware is always a stress riser in wood construction, and you have to design for that. The FAA guidelines are that any hardware, such as the bolts that hold a propeller on, should be a force fit into the holes. This distributes the stress across the whole width of the hole, and, at least in theory, produces a shear load at the edges of the hole rather than a sideways splitting force. I usually try to set the dowel nuts in some slow setting CA to help distribute the load. Avoid over tightening the bolts.

[Peter Wilcox]

I've never made a guitar without at least one mistake. You learn how to correct the mistake, so when you make the same mistake again you know how to fix it.

Hang in there.

[Karl Wicklund]

Better than my resonator which has sat waiting since 2007 when my first child was born. I can’t even start fixing the mistakes on that one, because I haven’t made them yet!

[Alan Carruth]

You get to be a master when you've made all the mistakes, and don't make them again. There are so many....

[Pat Foster]

You get to be a master when you've made all the mistakes, and don't make them again. There are so many....

I have this vision where mistakes hover over my bench like a specter, waiting patiently to descend.

[Clay Schaeffer]

When using cross dowels some people recommend using side reinforcements to the tenon to strengthen the end grain the metal dowels bear against. If you already have the sides of the tenon fitted you can slice an eighth of an inch off the end of the tenon and replace it with a 1/8th inch thick piece of long grain hardwood (rosewood scrap?) firmly glued to the end grain. That will provide additional strength without adding too much trouble.

[Colleen McTigue]

When using cross dowels some people recommend using side reinforcements to the tenon to strengthen the end grain the metal dowels bear against. If you already have the sides of the tenon fitted you can slice an eighth of an inch off the end of the tenon and replace it with a 1/8th inch thick piece of long grain hardwood (rosewood scrap?) firmly glued to the end grain. That will provide additional strength without adding too much trouble.

That’s the plan. Got the headstock veneer glued on yesterday. Today I plan to rough out the headstock.