Masaru Kohno Model 20: New Bone Saddle


1. Measuring for the New Saddle. This finely crafted guitar had a saddle that was just a bit too thin (definetly an aftermarket modification). Because of this, the instrument wasn't quite living up to it's full sonic potential.	2. Choosing a Suitable Bone Blank. After taking multiple readings from the bridge with my calipers I headed to the "bone yard" to find an appropriate replacement.


3. Measuring the Bone Blank. Just a few thousandths of an inch thicker than the bridge was designed for is all I need.	4. Thickness Sanding the Blank. Hand sanding the bone blank to rough thickness was a quick and accurate task with 220 grit sandpaper on our shop's dead flat granite slab.


5. Checking the Blank with a Straightedge. The material from the bottom of the blank is usually taken away toward the end of the process while fine tuning the action, however, I'm always much more comfortable having all surfaces square and flat before con- touring the top of the blank.	6. Rough Sanding to Length. A quick trip to the disc sander brought the bone blank down to rough length. I also ground in the appropriate ange into the ends of the blank.


7. Marking the Ends for Final Shaping. I sanded the sides of the saddle up through 600 grit. At this point the saddle had a nice tight fit. I then layed out the finished ends of the saddle by scoring the bone with a knife.	8. Final Shaping of the Ends. Back to the granite slab and the 220 grit sandpaper for final shaping of the saddles ends.


9. Shaping the Top of the Blank begins with matching the contour of the fretboard's radius. In this case, nearly flat. Rounding over the ends follows.	10. I Crowned the Top of the Saddle, leaving the high point at the center of the blank. This is a reasonable compromise between the saddle's strength, maintaining accept- able string tension and the saddle's tonal characteristics.


11. Final Shaping of the Saddle's Crown. After shaping the top of a saddle blank with a file, I sand the bone with sandpaper starting at 220 grit to remove the file marks. I'll then sand the saddle up to 600 grit in preparation for polishing.	12. Polishing the Saddle begins with steel wool (#0000) and proceeds through fine sanding pads ending at 12,000 grit. This is a finer polish than the back of our edged tools recieve from the shop's Japanese water stones. The portion of the saddle's sides that protrude from the bridge are polished as well.



13. Layout for Adjusting the Action. After a quick test fit I've calculated that the action at the 12th fret is .5mm taller than I believe my client would find most comfortable. Since the 12th fret divides the scale at the half way mark I set my mechanical pencil's lead to protrude 1mm from the pencil. Removing 1mm at the saddle will reduce the action at the 12th fret by .5mm.	14. Layout for Adjusting the Action Continued. Marking just how much I want to remove from the bottom of the saddle with the pencil lead will prevent me from accidentally removing too much stock on the quick and course cutting belt sander.


15. Adjusting the Action. After the belt sander, a quick trip to the granite and a few passes over the ever so slightly concave side of a mill file, the bottom of the saddle will be flat and smooth. It's important that the saddle fit snuggly not just on the sides but also on the bottom. Otherwise the volume and clarity of tone that a nice classical guitar like this one is capable of producing will neve be realized.	16. All Done. With a new, properly fitted bone saddle this guitar is ready for the concert hall! (don't worry, I'll cut off the excess string behind the bridge later)


17. What terrible technique! I guess I'll just have to stick to fixing them...