There are many reasons to change the nut. A change from industrial plastic casting to handmade bone saddle is desired, the old nut is filed too deep, the distances between the strings are not correct and there is no more room for correction.
First, the strings are removed and the old nut is taken off. The nut blank is simply a rectangular piece of bone that is slightly taller and wider than needed, but already has approximately the correct dimensions in depth. This piece of bone is now inserted into the slot between the fingerboard and the head, and the excess is marked on the side and the top. Now the nut blank is taken out again and brought to the correct length with a saw. It is then roughly sanded into shape with the belt sander. The fine sanding is done with a special file that was made in-house. For this purpose, sandpaper is glued on both sides of a long, narrow wood. The accuracy of fit is checked by insertion, and the blank may be removed and further corrected one or more times. After this work, the bone nut already looks very organic. Only the underside is now straight, all other edges are smoothed.
Now the string spacing is marked with pencil, then the strings are loosely fitted. With the help of an arsenal of small special files, the notch for each individual string is now filed. While doing this, the appropriate string is carefully pushed aside to work on the bone, again and again, and onto the notch to check until the correct width, depth and alignment are achieved. The whole procedure is repeated six times, highly concentrated and precise, because the nut offers little opportunity for correction once a mistake has been made. Due to the different thicknesses, each individual string is again just as much a challenge as the previous one, because a standard procedure is not possible here.
Once everything is ready, the strings are tuned and final corrections are made, because only in a state of correct tuning can the notches be optimally adjusted. Once this process is complete, nothing stands in the way of playing pleasure.