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more... GuitarsGearDIYHow-TosGuitar & Bass ModsApril 2012

DIY: How to Intonate a Flattop Guitar

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DIY: How to Intonate a Flattop Guitar

Step 9

Compensate the New Saddle
Intonating a guitar involves adjusting the length of each string so it will play in tune along the entire fretboard. Conceptually, it’s simple, but the process can be complicated—particularly on a flattop that doesn’t have individually adjustable saddles. Before we begin carving the saddle to subtly adjust the vibrating length of each string, it’s good to step back and look at all the elements that affect a guitar’s intonation.

The location and condition of the string nut, frets, and bridge saddle each play a role. For example, if the nut is too far or too close to the first fret, the guitar will never intonate properly. Also, if the string slots in the nut are worn, this will also prevent accurate intonation. This is why it’s a good idea to check the slots and make sure the nut doesn’t need to be replaced.

Frets also play a big part. When the frets begin to wear, they flatten out and change their point of contact with the strings, and this also affects the intonation along the fretboard. Recently, I had a guitar on my bench that had heavy wear on the first five frets. When I checked the intonation, those were the only notes that were out of tune. So if your guitar isn’t playing in tune, it could be some frets causing the problem.

Sometimes I come across a bridge saddle slot that’s in the wrong location on the bridge. When that’s the case, even after compensating the saddle, the strings still fret too sharp or too flat. In this case, you have to relocate the saddle or fill the old slot and route a new one.

Relocating the nut or saddle, or doing fretwork is beyond the scope of this article. However, if you have a guitar that’s built correctly—like Chapman’s Taylor 914—all you need to do now is carve the intonation points on the bridge saddle. This is called “compensating” the saddle.

Essentially, instead of having all the strings cross over the top of the saddle at its center, you’re going to create a unique resting point for each string. Some of these points will be closer to the soundhole, others closer to the bridge pins.
Here’s how I do it:


14. Checking the trailing angle for the low-E string as it comes off the saddle. The distance between the pin hole and the saddle determines this angle, and it’s important to file it correctly for each string. 15. Filing the B-string compensation after removing the bridge from the saddle. The mark you made earlier indicates how far into the saddle you need to file. 16. The B-string “notch.” 17. The B-string notch seen from the front of the saddle. 18. Check the trailing edge of each string to confirm there are no sharp edges and each string sits on a correctly angled surface for optimal volume and sustain. This saddle is now ready to be removed and given a final polish with 600-grit sandpaper and then a buffing cloth. 19. Cleaning the fretboard with ultra-fine #0000 steel wool. Yay, shiny frets! 20. Treating the bridge with a soft cloth sprayed with Planet Wave’s Hydrate.

1. Mask the bridge area around the saddle with strips of low-tack blue painter’s tape. This will shield the wood from any slip-ups from your file.
2. With a mechanical pencil, mark a line as described below to indicate where each string will cross the top of the saddle. This line will guide you as you file (Photo 10).
For the high-E string, place the line halfway across the saddle. For the B string, mark a line almost at the rear (pin side) edge of the saddle (Photo 11). The G string has its contact point close to the front (soundhole) edge of the saddle, so make its mark there. For the low E, mark a line 1/32" from the rear edge. The A and D contact points form a diagonal line between the low E and G contact points (Photo 12). The D will be just a bit back from the G, and the A will sit slightly forward from the low-E string.
3. With the saddle in the slot, gently begin to file the bone material away on either side of the high-E pencil mark to create a narrow ridge. This ridge will be the contact point for the high-E string. For now, keep it about 1/16" wide (this will give you some room to finetune the intonation point after you’ve completed the basic compensation). As you file, stop periodically to check the rear angle— you want it to match the angle of the high E as it comes out of the pin hole.
4. Repeat the process for each string except the B string, which you’ll carve separately after removing the saddle from the bridge.
Remember, the G string’s contact point is at the front edge of the saddle; from this point, the saddle will slope back down toward the G’s pin hole. The low E will only make contact at the rear of the saddle—1/32" from its edge. The A and D strings fall in line between the low E and G (Photo 13). Once you’ve removed the appropriate material from the rear of the saddle for these strings, file off any excess material from the front side of their contact points. Giving the strings a clean leading edge allows them to vibrate freely.

Tip: Each string will rise from the pin hole to the saddle at a different angle. You can easily determine this angle by turning your file on its narrow edge and laying it between the pin hole and the saddle (Photo 14).

5. Remove the saddle and file the compensation point for the B string, which will be just on the pin side of the saddle. In this case, you’ll remove material from the front (soundhole side) of the saddle to create a ridge at the rear. Using a small flat file, carve away the excess material from the front of the saddle (Photos 15 and 16). Essentially, this creates a notch in the blank.
8. Put the saddle back in its slot, install a fresh set of strings on the guitar, and tune it to concert pitch.
7. Look at the saddle to check your compensation. If you’ve done the carving correctly, the high E rides at the center of the saddle, the B sits on the rear edge (Photo 17), the G sits on the front edge, the low E sits close to the rear edge, and the A and D contact points form a line between the low E and G.
Now examine the saddle from the rear: Do all the strings come off the saddle and angle smoothly to their respective pin holes? To minimize string breakage, you don’t want any sharp edges here. Also, by having each string supported at the correct angle as it descends into its pin hole, you get maximum transfer of string vibration into the bridge (Photo 18).
8. Finally, when the saddle looks right from the front and rear, check the intonation again. If a string needs adjustment, file its contact point forward or backward accordingly.
9. Remove the saddle and polish it with 600-grit sandpaper and a cloth. While you’re at it, clean the fretboard with ultrafine #0000 steel wool (safe for fretboards, but don’t let it touch the finish) and then treat the fretboard and bridge with lemon oil or a lubricant like Planet Wave’s Hydrate (Photos 19 and 20). Reinstall the saddle, string up, tune to concert pitch, and you’re good to go.

The Wrap
There we have it. To get Chapman’s wellloved Taylor back in pro playing condition, I adjusted the truss rod, tweaked the action at the nut and saddle, and carved a compensated bone saddle to give the guitar a big sound and sweet intonation. This 914 turned out great, and I look forward to hearing it on more hit records!

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