F-hole guitar with floating bridge assembly project


 Lutherie blog

Hi everyone!




     Here is a cool project that I recently completed. A friend was building her first acoustic guitar and ran into some problems after she had completed the box and carved the neck. Too much material was removed from the heel of neck and the dovetail joint was not fitting together as planned. I agreed to take on the project to finish the rest of the guitar for her. Here is what I encountered:


Gap between neck heel and body, so what's the problem?

      As you can see the fit is pretty rough here. Way too much material has been removed from the neck heel. This is a tricky situation deciding where to shim things to end up with a tight fitting dovetail and the correct neck angle to project properly to the bridge, which in this case is a floating arch-top style bridge. I take some time to ruminate on the variables presented to me and work on other more straight-forward aspects of this project. I begin with the location and drilling of the post holes for the tuners.


Planning for the placement of the tuners
     Planning for the placement of the tuners is more work than most people realize. If the symmetry is off just a tiny bit it's quite noticeable aesthetically. Then the functional aspects have to be taken into account (i.e. will the strings have a clear path past the other posts etc).

Drilling the post holes
      The fingerboard inlays also need to be drilled and installed. She has chosen simple abalone dots. I begin by locating and marking the center of the frets to be inlayed. After drilling the holes I make a paste of medium superglue and ebony dust and fill the holes with it. The abalone dots are then floated into place on the liquid dust and glue and allowed to set before cleaning them up.


Abalone dots floating on ebony dust and superglue liquid before cleanup
Inlay cleanup and board planing in one step

      OK now it's time to tackle that dovetail joint, I can't really stall anymore. I begin by shimming the dovetail joint with thin mahogany pieces. I periodically test the fit of the neck as I plane the shims thinner and thinner in my thickness sander.

Mahogany shim planed to about 1/32"
Placing the shims
     To glue the shims in place i used the neck as a glue caul to get a good even pressure along the length of the shim. I placed waxed paper between the new shims and the neck to prevent the neck from becoming glued in place because i still have other fitting to do once the shims are in. Here I use regular old Titebond wood glue.

Gluing the shims into the dovetail
          Turns out that the dovetail wasn't cut completely squared to the center-line of the neck and fingerboard either! this complicates things a bit more. It's not too far off though so I use a piece of a business card to further shim one side of the dovetail to to get the neck to project properly. Now I need to shim the heel of the neck to get it to fit nicely to the guitar body. To do this I take two more small pieces of mahogany and glue them along the sides of the end of the neck heel.

No need to shim the entire face of the neck heel so I just shim a thin layer on each side with mahogany strips.
Trimming the edges of the new shims with a razor blade
     Now it's time for the final fitting and sanding process. I tape 120 grit sand paper down where the heel will contact the body and slowly sand the new shims by moving the neck back and forth in tiny movements.

Final sanding and fit of neck heel
     Now since I'm planning on a floating fingerboard tongue over the body, I need to install the frets past the body joint before joining the neck and body because hammering on the unsupported floating fingerboard will likely result in damage.

Installing frets on the fingerboard tongue before joining the neck to the body
     Now to join the neck and body, drum roll please! If finish work was to be done on the guitar this would preferably be the time to do it, but in this case we're leaving it bare wood. I score up both sides of the card stock shim that I'm adding to one side of the dovetail joint to get a good bond.

Gluing the dovetail joint
     Now I finish the rest of the fret work, make the nut, fit the bridge and do the final setup work.

Filing the fret edges after installing

I mask off the body of the guitar with thin steel sheets to prevent an unfortunate slip of my file from gouging the guitar during fretting
I fashion a simple truss rod cover out of spare Camatillo rosewood
     After installing the tail piece and some final setup details it's time to string it up.


She came out looking and sounding very nice!

     All in all, I would say my expectations were exceeded on this project. I'm going to deliver it to her in San Francisco next week, I hope she likes it.

     Thanks for reading everyone,

     Shane Dooley
     Luthier

For more information about me both as a luthier and musician visit me on the web at

www.DooleyGuitars.com

email me at

dooleyguitars@gmail.com

or come see me in my shop in Longmont, Colorado
Inside Guitars Etc
460 main st
Longmont, CO

Thanks again, see you soon!