This is an attachment I received to today for my fret-slot saw.

One can imagine that cutting the slots before the fretboard has been radiused can
make it hard not to leave an undetermined amount of space under the fret tang that
has to be filled or to shallow of a slot preventing the wire to press in.
The initial cut made by hand is when the fretboard is flat and squared- not yet with a radius or tapered. Opposed to something like a CNC machine that can make the cuts after the radius and tapered cuts are made. ( It's late and I'm tired...hope that makes sense.) I know "they" still have to fill-in after the CNC cuts too on unbound fretboards. I think MusicMan has a very cool way of doing it but I'm not sure how all of them handle it.
I wanted to improve how I handled that step. Repeatability with accuracy.
I think I've achieved my goals.
Now I can cut the slots and have the right depth. It's not perfect because fretwire isn't but it is
most excellent IMO.
Now I can make the first cuts and the depth is correct in the middle and after the radius taper are made then
I can set the cutting depth to the edges of the fretboard.
Since the saw cuts on the pull it's just a good, smooth, accurate method now. ( less chance of chipping the edge with cut made on the pull)
This shot was taken right after installing the frets- I filed just enough on the wires edge so I could see how well it worked.

Now I know the initial cut is spot on in location(s) and depth is correct from middle to edges of fretboard with minimal fill needed if any at all.
Major milestone in fine tuning one of the processes. Extra cutting steps added but well worth it IMO.
Smart tool attachment...glad I wised up and got it.