I got this GVR Hauser model with a great sound and beautiful Brazilian rosewood back and sides but with bad intonation. The owner suspected the fret positions and I corroborated that with calipers. The scale length is 655 mm.
I made a template with 1/4" MDF and put it next to the fingerboard making the 12th fret line up perfectly. I used the saw with the red handle as an indexer.
Here you can see how off some of the frets were.
Here is how I cut the slots.
I also made the new nut with compensation and a shim on the back to fill in the gap caused by moving it closer to the 1st fret. I think that a nut thicker than 3/16" looks wrong.
I made a saddle with individual string compensation,
and installed new Rubner tuners since the Schallers were a little stiff.
The owner was pleased with the result:
Hi Luis, I picked up the guitar today and after playing, I'm completely satisfied with the work and couldn't be happier. Thank you so much for fixing my guitar, the intonation and fret work is amazing, the saddle, nut, and tuners are perfect. You do beautiful work my friend!