I really like the science, math, and theory behind guitar work. I feel that it’s important to understand what’s happening with a guitar on a fundamental level, and this helps me analyze and fix complex problems. However, there are some jobs that require more art than science, and making a bone saddle is one of those jobs where I have to trade in my lab coat for an artist’s smock.
Contrary to what many people think, you can’t just buy a saddle off the shelf and have it fit perfectly. Every guitar is different, and each saddle should be made accordingly. I recently was brought a Taylor acoustic guitar with a missing saddle, which must have fallen out while it was being restrung. After explaining that I don’t sell off the shelf saddles, I offered to make one out of bone instead of the original synthetic (plastic) material.
First, I inspected the bridge route to make sure it was flat and true. Ascertaining this, I measured the saddle slot for length and width, and found a bone blank that was somewhat close in size.
I usually make my saddles and nuts out of cow bone – it works well, looks good, is resistant to wear, and is more readily available than unicorn horn and dragon’s tooth. Since making a bone saddle involves making a lot of dust, I wear a dust mask throughout the process.
I mark my measurements to the bone blank, and rough it in to get it close to the right size on the bandsaw and belt sander. From this point on, things get tedious: a bone saddle should fit easily into the slot, but shouldn’t be so loose that it will fall out. There’s no quick way to get this kind of tight fit – this takes time, patience, and elbow grease. I attach sandpaper to a perfectly flat metal block, and sand away just enough material to get it to fit into the bridge slot perfectly.
I rough in the curves on the saddle’s ends using the above method, and then put a perfect round on it using a fret file loaded in to a vice. The fret file is shaped to put the crown back into a fret after it’s been leveled, and just so happens to work beautifully for this purpose as well. Again, this takes some time, but anything worth doing is worth doing right.
Viola! A perfect fit!
The next step is to shape the top of the saddle. Here’s where the art really starts to come in. First I measure the fretboard’s radius using a radius gauge. This guitar’s radius measured at 38cm (14″):
I usually set my bridge radii to be slightly flatter than the fretboard radius. I find that this gives the impression of a lower, more comfortable action, where the player isn’t having to reach over the middle strings to reach the bass strings. Of course, I’ll make them anyway the player wants, but for the most part players seem to dig it the way I describe. I use the radius gauge to mark the top of the bone blank (in this case, 40cm (16″)), rough it in on the belt sander, and then use the appropriate radius block to sand it down to exactly the right curve.
Now it’s time to get fancy. I always compensate my saddles to help the guitar to intonate properly – the plain strings tend to run sharp if a straight saddle is used. Now, there are lots of ways to make a compensated saddle, but I’ve found that I’ve been favoring this method lately. I may shake things up and do things differently at some point – this part tends to be more about an artist’s discretion rather than a concrete way of doing things. I start by marking the saddle between the G and B strings, and then marking over the parts of the saddle that I want to carve away.
Using a variety of files, I carve the saddle to a sort of Z pattern. This offsets the strings in such a way that will help them play more in tune with themselves up and down the neck (inasmuch any guitar could be considered “in tune”).
Once I’m satisfied with the shape, I round the corners and then sand and polish away all of the file marks and scratches until it gleams. There’s something deeply satisfying about this particular step – what was once just a square chunk of cow bone is now something beautiful to behold. I don’t remotely consider myself a sculptor or any visual artist of any kind, but I know what I like, and I think I do ok with stuff like this.
Lastly, I install the saddle, string it up, and make careful measurements to set the guitar’s action. I always start with the saddle way too tall, so I can cut it down to it’s proper height. In order to set the saddle to the right height for the kind of action I’m aiming for, I take twice as much off the bottom of the saddle that I want the action to come down at the 12th fret. So: if the action at the 12th fret is 3mm, and I want it to be 2mm, the difference is 1mm, which means that I remove 2mm from the saddle. Make sense?
When removing material from the bottom of the saddle, it’s important to make sure that it’s DEAD flat, especially if there’s an undersaddle pickup involved. If the saddle’s bottom isn’t perfectly flat, it won’t be making complete contact with the bottom of the slot or with the pickup, and can cause tonal loss or dead strings if a pickup is used.
And there you have it! One beautiful bone saddle, perfectly fit.
Installing a bone saddle into your acoustic guitar isn’t just something to consider if you’ve lost or broken your original saddle. Many people report a better tone, as bone tends to be harder than materials commonly used in many acoustic guitars, and it transfers the strings’ vibration into the guitar’s top more efficiently. It’s a great, inexpensive way to make a tonal change to your instrument.