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more... Premier BlogHow-TosRepairGuitar Shop 101UpkeepFebruary 2014

Guitar Shop 101: How to Carve an Open-Slot Saddle

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Tip: When carving a bone saddle, it’s a good idea to add a little extra to your calculations. It’s easier to remove excess material than begin anew.


Fig. 6. Removing excess material from the saddle blank. You can do this by hand with a fine-tooth hobby saw.

Once the saddle is marked with the radius line at the desired height, you’re ready to cut down the blank. I use my shop band saw for this (Fig. 6), but you can manually trim off the excess material using a fine-tooth hobby saw.

To finish the basic shaping job, I like to flip the saddle upside down and sand the top on a 14" radius block fitted with fine self-adhesive sandpaper. This ensures a smooth surface and accurate radius. Radius blocks are available online, as are instructions to make your own, if you’re so inclined.

Once the top is shaped, slide the new saddle into its slot. Restring the guitar and check your action. Important: If the action is still too high, do not sand the bottom of the saddle. On an open-slot saddle, always remove material from the top of the saddle. Remember, the finished saddle has curved ends—which we’re about to finalize—and filing the bottom of the saddle will mean our “faded” ends will “fade away” and not match the bridge curves.


Fig. 7. Shaping the saddle ends to match the bridge contour on a drill press.
Another way to do this is with a Dremel rotary tool.

To carve those nice curves for each end of the saddle, I use a small spindle sander attached to my drill press (Fig. 7). Another option is to use a Dremel rotary tool, which also offers a high degree of control and precision. Go slowly and check your work frequently by fitting the saddle in the slot and comparing its ends to the bridge’s contours.


Fig. 8. Each string’s intonation point can be subtly shifted by removing material from either the front or rear of the saddle.

Carving new intonation points. After the saddle ends are properly contoured, it’s time to compensate the saddle. With the saddle in the slot, use a miniature flat file to carve the intonation points for each string (Fig. 8), based on the numbers you gathered earlier.

Each string typically emerges from the pin hole at a unique angle, and you want the contact point on the rear of the saddle to match this angle for every string. If the point of contact is too shallow or too steep, it can cause tuning problems and string breakage. By laying your file against both the pin hole and saddle contact point, you’ll be able to visually determine the correct angle for each string. Cover the pin holes on the bridge with a strip of painter’s tape. This way, if you slip when carving the angles, it won’t scar the bridge.


Fig. 9. Here, the B string’s intonation point is moved back toward the pin holes to extend the vibrating length of the string and slightly lower the pitch of notes fretted in the higher registers.

Earlier I mentioned the intonation was a little off on the 000-18’s original saddle. By filing the contact points forward for the flat strings and back for the sharp strings—especially the B string (Fig. 9)—I was able to improve the intonation. As you adjust the contact points, keep this simple rule in mind: When flat, move toward the neck. When sharp, move toward the pins.

To watch a video with a detailed, step-by-step explanation of how to carve the intonation points on a bone saddle, visit PG’s YouTube channel and watch “DIY: How to Set Up and Intonate an Acoustic Guitar.”

The wrap. I put new strings on the 000-18 and checked the intonation on my strobe tuner. Overall, the guitar played and intonated great, and it looked classy with its new saddle. Even if you don’t attempt work like this yourself, knowing what’s involved helps you communicate better with your local guitar tech. The more you understand about how your guitar is constructed, the easier it is to coax great sounds from it.

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