Neck Shims


Active member
When are those needed? My warmoth project has undergone a full setup and I still think its not right.
The Fret level is perfect, everything is dead straight. Fretboard is even (checked it with a stewmac ruler). Nut is perfect, not too low, not too high.

The problem : it sounds dead on some place of the neck. Just like if the strings are still bumping against the frets. EVEN with a super high action. Im confused. Maybe the neck pocket got a little angle in there?!?

I made a little drawing to explain it  :icon_thumright: enjoy!

So as I told you, I checked the frets and the fretboard. Everything is perfect. Tried different set ups and I cant get it where Id like to  :icon_scratch: (low & high action... neck relief, etc



Senior member
it could be that your frets are level but they still need to be crowned and polished. Another possibility is that you need to ad some relief to the middle of the fretboard or a ramp to the highest frets.

if it turns out that you do need to shim the neck than be sure to use solid wood and not some piece of cardboard. best of luck.

Patrick from Davis

Senior member
That sounds suspiciously like a truss rod adjustment.  I personally am not that big into the whole super low action thing cause I tend to strangle the guitar neck and bend the strings all over the place.  Generally the buzzing at the higher frets is because of low action on the strings or the truss rod being just a bit to tight.  I am not a fan of neck shims, especially when Warmoth makes such well designed stuff that does not need shims if used appropriately.



Senior member
You can play a dead-flat neck, but if it's not working at the highest frets loosening the trussrod a bit will help - 1/4 turn, string it up, see if it works, wait a few days to let it settle... it's a pain in the butt, but then you do want your guitar to work. String relief is measured by putting a capo at the first fret, and holding down the strings over the pickups. .005" is low, .012" is maybe average (a high E string is .009 or .010" usually). I just read these specs for Jerry Garcia's guitar:

Garcia played with high action 7/64" at the 12th fret, with .030" relief in the neck.  At the nut, the strings where also quite high at about .030" above the 1st fret.  The ebony fingerboard has a 16" radius and sports.  .105" x.45" frets.  The neck and middle pickups are 10/64" from the strings, and the bridge pickup sits 14/64" away.

That's the highest action and neck relief (.030"!) I've ever seen, but he was renowned for a clear, clean tone. It's all compromises and balancing, there is no single perfect setup for everyone.


Senior member
Things must be measured.  Terms such as "low" are meaningless.  There are mathematical limits to what can be accomplished.

Assuming a nut that allows about .005 under fret 1 when depressing the string at fret 3, and a "at pitch" relief of about .010, then your fret 12 clearance from string to fret top should be about 3.5/64th of an inch for the high e, and about 4/64 for the low E. 

That should get you about the minimum you can play and have any bending at the upper end of the neck.

Your shim picture does nothing that raising the bridge wouldn't do.  Neck shims are needed in cases of a very tall bridge (Telecaster/Bigsby) or Fender used the "micro tilt" feature as a way to partially adjust the way the Strat' s trem would work.  Generally, shims are applied at the inside of the neck pocket, not the outer (forward) edge.

Things like crowning always good to check.  Also, removing the finish from the frets....

You don't give enough information for a really good analysis of the problem.



Senior member
On what strings and on exactly which frets does it buzz?  Like CB said, we need a just a little more info.

In a perfect world, the plane of the frets should be just below the saddle by about 1/8".  Shims are usually used in lieu of sanding the pocket to change the entire plane.  Make sure there's no existing overspray in the front corner that might be already "shimming" it.