Frets are so misunderstood.
This is the thing that separates the men from the boys, so to speak.
Most import guitars (depending on what you pay for it) have bad fretwork.
Here's the deal! Frets have to be perfectly level and round on top to play and sound good at all.
9 out of 10 guitars have fret problems! The ratio is much worse I'm sure. It does not matter if it's a Gibson or a Custom shop Fender, production guitars are made too fast. ( see a customer's comment at bottom)The thing that seems to suffer the most is fretwork.
Mostly all it needs is a level and crown. $60
Every note you press is resting on a fret. Ever wonder why some guitars buzz like a Sitar? The frets are not level and round. The way a Sitar works is the bridge has a flat area in front of where the strings rest at the bridge. Each note buzzes on this flat area to create that Sitar sound. Most production guitars' frets are somewhat flat shaped creating a Sitar tone on every fret! This is due to the speed in which they are made. It takes time to properly dress the frets! More importantly, it takes great skill! Don't trust your frets to just anyone!
Here is an email you should read...
... I did have one question though about the
fretboard contouring/shaping that you're talking about. How is this
different than using neck relief, and does it affect the fretboard
Something I have discovered over the years are certain flaws in guitar MFG:
have to be able to make necks consistent, fast and profitable. And, therefore, cannot afford to pay highly skilled craftsmen to hand radius the necks.
So, all necks get made totally flat and level, with whatever radius is specified, which renders a consistent product - This is in contrast to the physics at work in every guitar, and causes a problem:
The lower notes vibrate wider than the higher notes, which causes the lower notes to buzz on the flat surface of the neck.
Therefore, you get your guitar and you set the truss rod tension to allow enough relief to play open chords without buzzing.
Then, you fiddle with the saddle height and get them as low as they will go so that the strings will not buzz too bad up past the the 12th fret.This
is difficult since the relief has turned the neck into a little ski
So, you go back and forth compromising between the two.
The end result is chords that buzz more than you want and action higher than you want for solos.
"It says (enter big name brand) on the headstock, so it must be good." WRONG!!!
notice how $100 guitars are just as shiny as $2000 guitars?
first thing to go is good fret work, quality wood and components.
Now to really answer your question: the
radius stays the same down the length of the neck...the treble side of the
neck gets a slight horizon or a hump the full length of the neck...the
bass side gets this hump from the xxx to the xxx fret then drops
slightly to a bowl shape with the highest point behind the xxx fret of
the bass side.
When string tension is applied the hump becomes as straight as a laser beam and the bowl more pronounced.
This allows the lowest notes to breathe with the amount of relief they need, without raising the other notes off the neck!!