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I have used a flap sanding wheel. A bit less scary than the Lancelot, but plenty fast enough.


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I use a Wagner Safety Planer to cut outside contours on the drill press, and finish off mostly with hand tools. The inside is dimpled using a stop block on the drill press table to establish the thickness contours.

So I've got the sides and blocks glued and in between glueing the solid linings in I'm working on the neck. It's going to be vertical laminations of sycamore and walnut. Question is should the fb extension support be part of the laminate glue up or is it a separate piece glued to the front of the heel and the underside of the fb?

Most of the production instruments I've seen glue a block onto the top, level it off to match the neck, and glue the fingerboard to that. I prefer to follow violin practice to a certain degree by extending a tongue of the neck out over the top and gluing the fingerboard to that. The fingerboard on a guitar is not as stiff as that on a violin because of the much lower crown, so it needs the added support, and you need something to tie the finger rest to, and support the pickup. You may have to have more 'overstand' than usual; make the fingerboard a bit higher off the top, to get enough depth on the neck extension to work. That can necessitate a taller bridge.

Keep in mind that, in terms of the loading on the top what counts is the break angle of the strings over the bridge. You can alter the neck angle to get that to come out right with practically any amount of overstand. I've done some experiments on this, and come to two conclusions:
1) with a notched bridge, which is common on archtops, you only need about 6 degrees of break angle, and
2) too much break angle can choke the sound.
More break angle doesn't result in a stronger string signal into the top. So long as the string doesn't hop off the top of the bridge as it vibrates all of the energy gets into the top. More down force just makes more problems down the road.

As with most instruments, the design sequence starts with the strings and the bridge, and you work everything else out to suit.

Really appreciate all the help so far. I just read my thread and thought I'd update a little, I'm going for a dovetail neck joint which my friend will help me with, back and sides are now American walnut reclaimed from an old victorian wardrobe. Neck is sycamore and walnut vertical laminations and fb is ebony, 25.5 inch scale.

I've a question about ideal truss rod length. I don't see the point of having the 'working' part of the truss rod extending much past the 12th fret on a 15 fret neck joint, I never like the idea of the rod pushing down on the neck block and up against the fb extension. I like the idea even less with a floating extension. Any thoughts on this?

Thanks all.

I went crazy with the fingerboard extension. Wedge shape would have been better. It is directly on the block only a little ways. The top there doesn't really do anything with a cutaway, so I could have gone up further. I had to cut the end of it down with knives and files a few times, when the belly rose at the beginning. Sometimes violins, and apparently arch tops do that; at least for me. I think the bridge rose a couple mm. The adjustable one that I bought was barely short enough to begin with; because of the 1" or so arching, so it had to be replaced with a solid one.

After the initial set up, and rising of the belly, it has been stable. I'm not a player, but it is always playable. 1 time I had to turn more relief in it, and it has been fine since. Even now in the basement 48 degrees, 32% humidity. The action is fairly low with medium 80/20 strings.

I just have a truss rod to the 12th fret or so; 14 fret neck; 325 scale. I usually work in mm. It is so much easier. I don't remember how long it was.

Yes it was a dovetail joint. But from the picture it seems that the notch for the extension was done AFTER the neck was set, or glued in. I’m guessing set. I don’t remember.

Making a viola now, and I use tapping/scratching for ALL the shaping. I get it looking reasonably like what I think; but still big. Then scratch, and remove the spots with high pitches. Use a little flat finger plane with long strokes. You will feel the high spots as you plane. You just keep doing that. I use plane, a spokeshave, and chisels for scraping. I don't use gouges for anything except maybe fiddly work in the corners, that a guitar doesn't have. It works amazingly well. The arching changes when you put in the f holes; it drops down from every direction; except from the edge.

If the wood is actually telling you that it is in tune; how can you go wrong. I have an arch top back and top almost carved out and tuned. I was just trying to figure out what I really wanted to do with it. I think I know now, so I'll be working on that too.

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Why be normal?

Mike, when I built mine (mentioned above) I made the fretboard extension a separate piece of wood glued on much as Benedetto describes but I ran two carbon fiber beams on either side of the truss rod to strengthen the extension. It is almost too stiff, a set of light gauge strings barely pulls any relief.





I don't remember the length of my truss rod but you can get some idea from the photos. I did use a dovetail joint