How to Set String Spacing for the Bridge on 12 String Guitar
The bridge of the guitar is the foundation for the saddle to sit on, which gives strings their rise above the fretboard and anchors the strings when the ends are pinned in pinholes drilled through the bridge and guitar top. String spacing is determined by the spacing between the pinholes. Twelve strings are arranged in six pairs. The distance between individual strings in each pair, and the distance from the first and 12th strings to the fretboard edges is consistently 1/8 inch. Spacing between string pairs and the remaining pinholes is calculated and applied after the first and sixth pairs' pinholes are determined.
Things You'll Need
- Undrilled bridge with saddle
- Low-tack masking tape (1 inch wide)
- Pencil
- Bridge clamp
- Fret ruler
- Drill with 5/32-inch brad point bit
- Tapered reamer
- Hyde glue
Instructions
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Position the Bridge
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1
Cut 8-inch strips of masking tape and stick them on the guitar top covering the area of the bridge location. Center each strip from side to side, one under the other and slightly overlapped.
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2
Draw the guitar's center line and two additional lines that extend the edges of the fretboard on the taped area. Use the fret ruler to keep your lines straight.
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3
Clamp the bridge on the taped area of the guitar top so it is centered from side to side, parallel with the shoulders, and the bridge saddle is the end point of the scale length.
Locate Boundry Pinholes
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4
Measure 1/8 inch from the fretboard's bottom edge to its center at the nut and 16th fret. Place the fret ruler along these points so it extends over the bridge. Scribe a mark along this line on the bridge 3/8 inch behind the saddle. This marks the first pinhole.
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5
Measure 1/8 inch from this mark toward the center line, then draw a line to the saddle. Mark a point along this line that is 7/8 inch behind the saddle. This is the second pinhole location.
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6
Measure 1/8 inch from the fingerboard's top edge to its center at the nut and 16th fret. Place the fret ruler along these points so it extends over the bridge. Scribe a mark along this line on the bridge that is 7/8 inch behind the saddle. This locates the 12th pinhole.
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7
Measure 1/8 inch from the 12th pinhole mark toward the center line, and then draw a line to the saddle. Make a mark along this line 3/8 inch behind the saddle. This is the location of the 11th pinhole.
Calculate Spacing Between Pairs
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8
Measure the distance between the second and 11th pinhole locations.
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9
Subtract 1/2 inch, which is the sum of spacing needed between individual strings in the remaining pairs.
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10
Divide by 5 to get the spacing measurement applied between string pairs.
Locate Remaining Pinholes
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11
Measure the calculated spacing from the 11th pinhole to the center line, draw a line to the saddle and make a mark along this line 7/8 inch behind the saddle. This marks the pinhole for the first string of the next string pair.
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12
Measure 1/8 inch from this pin hole toward high E, draw a line to the saddle and then mark the point that is 3/8 inch behind the saddle. This is the next pinhole position.
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13
Continue these steps to locate and mark the remaining pinholes.
Completing the Project
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14
Remove the clamp, bridge and tape from the guitar top.
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15
Drill the pinholes in the bridge using the 5/32-inch brad point bit.
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16
Glue the drilled bridge on the guitar top so it is centered from side to side, parallel with the shoulders, and the bridge saddle is the end line of the scale length. Clamp until dry.
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17
Drill through the soundboard using the bridge pinholes as a guide, then ream each hole for proper pin fit.
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1
Tips & Warnings
Spacing can be adjusted to compensate for thick-gauged strings.
Lay out on scrap first.
Drill with the bit centered on marks and perpendicular to the bridge surface.
Work slowly.
This procedure is not reversible once the holes are drilled.
References
Resources
- Photo Credit Ablestock.com/AbleStock.com/Getty Images
