Archtop build

[Brian Evans]

I thought I would try to show some pictures of my current project. It started out as a nylon string archtop, but has evolved to more of a cross-over classical to archtop, and is intended for low tension steel strings (probably .011" - .052" or thereabouts). Its design is pulling most major dimensions from a classical guitar - scale length, neck width, relationship between lower waist and neck, neck joins body at the 12th fret for the shoulder. It adds some archtop things, like a 16" body width, 20" length, 3" depth. I added some flair - the body is asymmetrically shaped, pulled down at the bottom and up at the top, kind of like a Strat, and the body joins the neck at the 14th fret for the lower shoulder. The bridge is located in the very center of the lower body. The sound holes are cut-outs in the upper body, and there will be four or five fan braces from the neck block all the way down across the belly. There will be an internal strut, of dovetailed maple, between the neck block and the tail block completely relieving the top from any need to resist string tension

The woods are sitka spruce for the top, flamed maple for the sides and spanish cedar for the back and neck. The idea is that the sides will be fairly solid and well damped, and the back will be as lively and resonant as I can make it, I felt that spanish cedar was a good wood for that. It will be a red/yellow sunburst, to help evoke the fire in the top cutouts.

The influences are obviously the Benedetto Il Fiorentino, and the 7 string nylon archtop shown on his website. The body shape is reminiscent of work by Pagelli, although I confess I drew my body before I found his website and saw his designs, so I think I can claim it's legitimately mine. The strut between neck and tail block is reminiscent Larson Brothers work, they had a steel bar under tension, and some Epiphone archtops had a steel strut in the same location. The whole instrument is inspired by the playing of a friend of mine who is a great jazz and improvisational player who has been playing classical guitars lately, but is wonderful on her Guild archtop.

[Beate Ritzert]

This is going to be interesting. Unfortunately no response on it
I would be glad to see more pictures of the progress.

[Brian Evans]

I rough carved the neck today, maple with padauk fretboard, rosewood head veneer. I thought it was odd no one thought my project was worth commenting on too. Oh well. Thank you for noticing.

Brian

[Barry Daniels]

The pictures could have been better. But, nevertheless, sorry we missed this.

[Ed Lysne]

Elegant look. I like it. Show us the bracing when you get it worked out. Are you planning a pickup?

[Brian Evans]

Here are a few more pictures. The bracing is somewhat based on Benedetto's fan braced guitars, and I added a round maple brace directly between the head and tail blocks to take all of the tension from the strings off of the top. That's been done before as well, some 1940's Epiphones had such a brace (of metal). I felt the sharp points on the sound holes were crack-magnets, so I put a very thin layer of fiberglass cloth behind them as a reinforcement. I feel that area of the top is pretty dead acoustically anyway. The braces extend all the way up the belly of the instrument, the idea being to extend the tone production all the way up to the neck block. The braces will be quite thin and tapered, but are 5/16" wide at the base, and are made from off-cuts of the top. Inch thick archtop blanks are handy that way, you get lots of useful brace material left over. The top will be thin for me, around .190" tapering down to .120" at the edges. I plan on a floating pickup, thinking of a DeArmond style, but the string width at the end of the neck may be an issue, since it is based on a classical guitar's geometry.

The sides are curly maple that I got as "samples" when I placed an order with Bow River Woods, so they were actually free. The back is spanish cedar. The binding is tortoiseshell celluloid. The guitar in the background is the flamed curly redwood archtop I made last year.

[Brian Evans]

Here it is as of today. Neck 95% carved, neck set complete, assembled for the first time. Fretboard is padauk, headstock is rosewood with a birdseye maple diamond. Scale is 25.6", 21 frets, bridge location is in the geometric center of the lower bout. Next is the final graduation of the top and back, finishing the inside, and closing the box. At that point it will be 95% complete, and the other 95% (all of the finishing!) can begin...

Brian

[Bob Francis]

Nice work Brian

[Randolph Rhett]

FWIW, using a wood dowel as an axial brace may be a mistake. From experience a wood dowell 20" long will expand and contract with the weather enough to either allow a light top to collapse or crack the head/tail block. Of course it will depend on the wood the dowel is made of and how well seasoned.

[Brian Evans]

Randolph, my thinking was that the wood (commercially dried maple dowel) is long grain, as is the top and the braces, and the braces are almost parallel to the axial brace. So I thought the movement would be pretty similar. The inside has been finished with shellac, as well. So we will see, it is an experiment after all, and that's why you do experiments - to see what happens! I had the exact reverse thought about using steel or carbon fiber - that they would not move at all, and cause problems.

Brian

[John Mueller]

Search the old MIMF library for"Moll thinline archtop" and you'll find Bill's thoughts about adding block to block bracing. I did it in my build and no problems in the past 12 years.

[Mario Proulx]

I've used block to block dowels in mandolins, too. Works a treat....

But why is your end block so massive? That has got to be heavier than heavy....

[Brian Evans]

That will probably be classified as a mistake, at the end of the day. I am anchoring the tailpiece through the top into the end block, and one iteration of the design had the tailpiece anchored fairly far forward, hence the tail block is fairly far forward. It actually acts as a good counterweight for the maple neck, too, so it might work out.

The tailpiece will be wood, with a spherical bearing inset acting as a mounting point via a bolt going vertically down through the top into the tail block with a nut insert in the tail block. It will appear to float over the top with no instantly visible means of attachment. I may or may not make the mechanical bearing a design feature, or hide it under a cap. I also plan to look at mounting the volume and tone controls on the tailpiece, and a mini-jack for any pickup I decide to mount.

Brian