Wednesday, August 12, 2009

Mandolin Post #5 Fret Board and Bridge Fitting

I begin this week with the " Fret Board" this is a strip of Ebony Wood . It is rectangular in shape and has to be cut to fit the Mandolin neck that was made. Better Luthiers will cut the fret slots personally. However since this is my First attempt. I chose to purchase a "pre-Cut" fret board. The Board Came to me Rectangular with the narrow slices for the wire frets already cut in place. The distances are extremely crucial to a good sound and I wasn't ready to tackle that aspect yet.

As you see in the pic below I have cut the fret board to length and shape . I put it on a solid piece of Oak wood and Hammered the Fret wires into place , This needs to be done with ( 1 ) blow of a Hard Plastic Mallet , excessive blows will bend the wire and then allot of sanding is required to fix them.
Each Fret wire is cut over sized and hammered into the pre-cut slots. Then they are trimmed to length. The fret wire has a tang that has teeth that will grab i the slots and hold. this is not and easy job. it took me a couple hours and several messed up frets to get it right.

In the Pic below I have drilled and glued in the pearl inlay dots I chose for my fret board. These are set in the center of the # 3 / 5 / 7 / 10 / 12 / 15 frets . You will notice the 12th fret has 2 dots . This is the octave fret. As you can see they are smaller than a pencil eraser and I drilled the holes with a 5/32" mill bit to get a flat bottom hole .

In the pic below I have fitted the fret board to the neck of my Mandolin and have it glued in place . To the left end you can see the access hole to open and tighten or loosen the tension rod nut if the neck needs adjusting. Yo will also notice that I have chosen to make this a flat top Mandolin , moving away from the basic shape of most Mandolins made today.

The below pic shows the Bridge that set at the back of the Mandolin and holds the string spacing properly. The distance from the " Nut" of the Mandolin ( the white bone glued in the neck at tension rod end, see last pic) to the 12th fret ( two dots ) is the same dimension as the 12th fret to the bridge . When I measured it out you will see that the bridge ended up being approx 1 inch from the sound hole.

What I am checking here is the height of the Bridge in relation to the Fret Board. I had to sand the bottom of my Bridge down quite a bit and modify the top so that i could get the desired height of my strings . This is called the " Action" and I will get into that more later. The desired height I am working for is approx .100 above the frets.

The below pic shows the unit glued together and standing in my shop. Remember when I said I had let the outer shell of the Mandolin take its natural shape prior to gluing back on. If you will look at the below pic and imagine a straight line down the center of the fret board to the tail piece . You will notice the tail piece has mover and the detail is not on center . I thought it gave it a little more personality.

In the next pic I have made the tension rod cover from the Mahogany left over from the top and am using it to hold the "Nut" in place while it glues. The height of the nut is determined by the fret wire height, so the distance the fret stands above the board + .015 " for String action + approx .030 " for a string grove will give you nut height. This is crucial and required a set of thickness gauges to get set properly.

well that ends this post of the Mandolin Project . I hope you have enjoyed reading and following my little project . Have a great week and stop by again.
Feel free to leave comments , I would love to hear your thoughts.

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