By now, the strings are set in place and I'm happy with their
location. It's time to start adjusting the slots to their final height.
I'm going to use this page to discuss various ways to set nut slot height.
 |
From the side you can see how shallow the nut slots are
at this stage and how high off the frets the strings are. |
 |
There are basically two methods of setting nut slot
height. Here's the first. Hold the string between the 2nd
and 3rd fret and adjust the nut slot that each string just barely clears
the 1st fret. The distance is so small that I can't even
photograph it. It'll be just a sliver of light. I use this
method as a quick check, but I prefer to measure the nut slot height
directly by using feeler gauges at the 1st fret. Here's why..... |
 |
...the nut height and 12th fret action are not
independent of each other, but affect each other. The above
technique takes the action out of consideration, but if a person has a
particularly high or low action, it can affect the actual height of the
string off the fret. This and the next photo show the opposite
effect, but same principle. In this shot, the string is sitting flat
on the fret with no clearance at all. |
 |
And here's the 12th fret action for the above shot.
You can see just a little clearance between the bottom of the string and
the top of the feeler gauges. That's .103" worth of feeler gauges,
by the way and the action itself is close to .110". |
 |
Here's the same guitar with the same un-touched saddle
AFTER the nut height was set. There is significantly more
clearance this time and the action measured .120". So, the action
at the 12th fret went up by about .010" as a direct result of raising
the nut slot. We can see that the converse is true, too. When I
dropped this action to .100", the string clearance at the 1st fret also
dropped. The nut slots themselves didn't change a bit, but the
clearance did. Since the nut height is there to adjust clearance,
it makes sense to me to measure clearance directly rather than use an
indirect measurement like the 3rd fret/1st fret gap method above.
As a further illustration of this, eyeball your current 1st fret
clearance. Then reach over to the 12th fret and pull the E string
up about 1/2", simulating a higher action. The 1st fret clearance
increased. Likewise, if you push the E closer to the 12th fret,
the 1st fret clearance decreases. Therefore, if your action is a
little high, you could cut the nut slot a little deeper than the "gap"
method might suggest, and if your action is a little lower, you might
leave the slot a little higher. In any case, I prefer to measure
fret clearance directly WITH the approximate action I'm going to use. |
 |
How do I decide what height to set clearance? One
way is to simply measure well-playing guitars. That's what I did
at first- I just found guitars that played well and measured neck
relief, 12th fret action, and 1st fret clearance until I had enough data
to establish parameters. But, there's another way..... First,
make sure your neck relief is acceptable. Then, set your action
via the saddle to "pretty close". Put a capo on the 4th fret and
play open strings. If they buzz, raise the saddle. When
you're happy with the buzz-free-ness of the capo'ed action, measure the
clearance of each string at the 5th fret. Write this down. |
 |
Move the capo back to the 2nd fret and repeat the
playing test. If satisfied, then repeat the measurements.
Write them down. |
 |
You'll probably have something that looks like this:
E: 5th fret = .012", 3rd fret = .014".
Extrapolating from this, it makes sense that you could set the 1st
fret clearance to .016". In practice, I usually add .002" to
account for increasing string length, nut wear, and just a general
"fudge factor". So, I'd set this nut so that the string clearance
was .018" at the 1st fret for the low E. This will result in an
instrument that plays as well open as it does with a capo. Also,
if the action changes, the 1st fret clearance with change
proportionally.
While this is a lot of work initially, after you do 100 or so, you'll
quickly see that an action of, say, .105" will work well with a nut
height of .022", and an action of .085" works with a nut height of
.016", and so on. You could probably make a spreadsheet to
calculate predicted 1st fret height. I still like to just measure
the instrument directly. |
 |
In this shot, I have the low E set and am dropping the
A string down. It's very clear from this shot that you can
accurately measure these things. That's a .022" gauge under the
strings and if you look very closely you can see a tiny sliver of light
under the low E string. There's an obvious gap under the A. I'm
going to set this A to .020", but used this gauge to illustrate a "done"
string and one "yet to be done".
I noted earlier that changes in the nut are reflected in the 12th
fret action and vice versa. In this example, the A is close enough
that it won't make much change at the 12th fret. I set the nut
"close" using the gap method, checked the 12th fret action, left it just
a smidge high (.005" or so) and then proceeded to fine-tune the nut.
When I'm done, the 12th fret action will drop right to where I
want it and if not, I'll fine-adjust it. |
 |
Here's the nut roughed out with the string heights set.
I'm ready to remove it, file down the top, polish it and reinstall.
Note that my pencil marks are still there! |
 |
And here's the finished nut. It wouldn't hurt for
me to remove just a little more of the top of the nut so that 1/2 the
string is exposed, but it's easy to go just a little too far and ruin
the nut, so I'm probably going to just leave it alone. I've
polished the frets and have glued the nut to the fingerboard with a
smear of bottled hide glue. Note that the tall Grover Rotomatic
tuners give a fairly shallow, and poor, break over the nut. If
those holes were down about the top of the hex nut, we'd get a lot
stronger break angle. |
And that's a nut the Kimsey-Way, folks!!! Yes, I know that Stew Mac
makes a cool little gauge for spacing nuts, but I have a caliper, math doesn't
scare me, and I'd use the caliper to set the E's from the edge anyway.
Just for reference, it takes me 40 minutes, start (guitar on the bench) to
finish (playing the guitar). The longest time is spent taking the slots
down to the height and then finishing and polishing the nut.