Second dometop archtop

[Dennis Duross]

Sitka spruce top
Wenge fingerboard, etc
Ambrosia maple back and sides
25" scale

The top and back are each made of 10 bent slats each, and conform to the arch of an 11-foot diameter sphere---which works out to a roughly 1-inch high arch.

No recurve.

The top is .15" thick (60-degree x-braces, 5/16 x 5/8), and the back is more like .165" thick with no braces.

Sides are laminated, 1/16" thick poplar on the inside, 1/16" ambrosia maple on the outside, and 1/64" baltic birch inbetween, cut across the grain for maximum flexibility.

Three-ply laminated poplar linings.

[Dennis Duross]

The tailpiece (above) is 1/8" aluminum clad in wenge, and attached with a single socket bolt threaded into the tailblock.

It sits about 1/4" off the surface of the soundboard.

[Dennis Duross]

You may be able to see the 1/4" access hole in the heel of the neck (below) that lets me attach the neck.

[Dennis Duross]

Here you may get a little better idea of how the dome shape resolves to the rims. The deepest point around the perimeter is at the waist (4"), and the shallowest is at the neck and heel blocks (3").

Total depth from arch to arch is 5".

[Dennis Duross]

Unfortunately I blew through the ambrosia back wood that actually MATCHED the side wood, so the back isn't exactly like the sides.

But my favorite part is the three knots, and especially the open knot.

[Dennis Duross]

Here are a few pictures of the neck joint. The pic below shows it all screwed together.

[Dennis Duross]

Here, I've taken the tenon off the heel, and you can see the recess in the heel that contains the knock-down bolt head, lock washer and flat washer.

[Dennis Duross]

And finally, here's how the bolt is tightened and loosened.

[Patrick Hanna]

Hey, Dennis, I'll chime in. Your guitars are very interesting to me. I'll tell you flat out that I personally wouldn't build an archtop guitar this way.

HOWEVER.......

I'm currently working on my second induced-arch mandolin. It's not as big as your guitar, but the concept is exactly the same--right down to the contours where the top and back meet the sides. Seems to me that if it works for my personal use, it'll work for you, too.
You carry on, man. You won't find a lot of market acceptance (and neither will I, but that is not my goal). If this is your personal guitar, you don't need to worry about market acceptance. You might still have a fine player in your hands. I certainly hope it turned out the way you intended. If not, just keep experimenting. Experimentation is right at the heart of this entire forum.

Continued good luck to you. Keep us informed!

Patrick

[Dennis Duross]

Thanks, Patrick.

I'm just building for myself, so I guess that makes all kinds of idiosyncrasies forgivable.

You're not the first one to remark that this wouldn't be their first choice of building methods, but I find that it seems to suit my sensibilities, so for the time being I'm ok with it.

I have to say that I'm very pleased with the sound of this guitar. Forgive my lack of descriptive terms, but it's got a lot of volume to it, nice clarity both across and up the board, and pretty balanced in terms of the strength of bass, mids, and treble. Good sustain too.

Unfortunately I don't currently know any knowledgeable players or builders, so take all that for what it's worth.

This was my first attempt at French polish, which I kind of liked---but I need a lot more practice at it. I used Watco on the neck and on all of the wenge.

[Mauro Marchesini]

Very interesting guitar, and even very beautiful

Dennis, on the pictures it seems that the tenon is only screwed to the neck, without glue, so the neck itself is held in place only by those two screws, IMHO too small. I would glue together the two parts.

[Darrel Friesen]

Out of the box cool Dennis. Are you pleased with the sound?

[Andrew Porter]

Despite general acceptance issues, I think you have an attractive guitar there. Is the neck adjustable?

[Dennis Duross]

Thanks for the replies.

The neck joint pictured above was actually my first attempt. As you can see from the exploded view, my original setup (for locating the holes for the tenon screws and for tightening/loosening access to the knock-down bolt) was not great. I worked that out better the second time around, but you get the idea. Two screws hold the tenon to the heel, and the knock-down bears on the tenon from the other direction, and is tightened to the neck block (which includes a t-nut) via the access hole.

The heel (like the neck) is 3-piece. The outer pieces' grain runs parallel to that of the neck, but the center piece of the heel is oriented at 90 degrees, so that it presents side grain to the tenon screws. Not sure if I'd do it that way again or not, but that was the rationale.

I had intended to also glue the tenon to the heel (thanks, Mauro), but wanted to see how it went without glue (commando-style) for awhile. I haven't noticed any pull-away where the heel and body join, but it's probably too soon to know for sure.

The neck is NOT adjustable, as I figured that's what the adjustable bridge is for. But I may look at that at some point in the future.

And yes, I am very happy with the sound---it's clear and strong, and very articulate. But again, take that for what it's worth. This is just my second guitar.

I forgot to mention that it's 17.375" across the lower bout. Don't ask.

So it's a little on the big side. But because the curvature of the dome reduces the depth of the rims where you sling your right arm over it, it ends up not really feeling like a tuba.

[Dennis Duross]

A little bit better photos.

[Dennis Duross]

And another.

[Dennis Duross]

Remarkable that it stands up so nicely. I think it rests on the flat base of the tailpiece.

[Dennis Duross]

Last one. It could use a trussrod cover.

[Dennis Duross]

One last note on this project. I changed the base of the bridge about a week ago to the version pictured below. Doing so actually made a noticeable improvement in the sound. I don't know exactly how to describe it, but by comparison, the lower strings---especially the 5th and 4th---are now a little more distinct or clear or something. Fretted notes seem to have better focus, and their sound dissipates at a rate closer to the other strings. I don't know what I'm trying to say exactly except that the dang thing sounds better now.

[Mark Swanson]

I suggest that it would sound a lot better if you got rid of the heavy tunomatic and went with an all wood bridge. Cool guitar.