The string length had a tendency for 652 mm. The last frets fitted well, so I decided to take the 18th fret for reference. I removed the 19th fret , glued an ebony stripe into the slot and leveled it with the surface. Then I prepared a wooden block (with my model saw) as a guide for the fret saw. The width of the guide block was the distance between the 18th and 19th fret position minus half the width of the fret and minus half the width of the saw slot (fret tang). I taped the block onto the fretboard , resawed the slot and set in the new fret. Finally I had to level it flush with the frets around it, and then I profiled and polished it.
The result was a 19th fret in the right intonation position.
The customer loved it and we both enjoyed the mature sound of a 100-year-old instrument!
