How do you know when to shim a neck?

[Nathan of Brainfertilizer Fame]

Or is it just a personal preference that is never actually necessary?

[Dave Scepter]

18 minutes ago, Nathan of Brainfertilizer Fame said:

Or is it just a personal preference that is never actually necessary?

It depends... if it's a surface mount Floyd and want some pull up or if your bridge doesn't allow adjustment to lower the strings

[hamerhead]

If the bridge is as low as it will go and the neck has the proper relief, but the strings are still a mile off the fretboard, you need a shim.

[kizanski]

51 minutes ago, hamerhead said:

If the bridge is as low as it will go and the neck has the proper relief, but the strings are still a mile off the fretboard, you need a shim.

There it is.

[JGale]

3 hours ago, hamerhead said:

If the bridge is as low as it will go and the neck has the proper relief, but the strings are still a mile off the fretboard, you might be a redneck.

FTFY!

[Jeff R]

If you're OCD about air space in the pocket due to shimming; and/or if you're shimming a flatsawn and/or soft or spongy species neck; and/or if you will gladly pay a premium for whichever reason, even if it's peace of mind ...

These are the Cadillac of neck shims. 

 

[Jeff R]

Addressing Nathan's confusion ...

Shimming is absolutely necessary in many cases if you expect superior set-up results, for the reasons stated earlier in the thread. I've found factory shims in grail-era pre-CBS Fenders (material ranging from pickup flatwork to business card stock to even a tear-off from a cigarette pack packaging), and in the pockets of some really high end superstrats. As stated above, tremolos and the desired rate of pull/drop, especially if extreme, are a frequent catalyst. 

A partial pocket shim - aka a sliver of material that only covers 1/5 or 1/4 of the bridge side of the pocket - can actually lift the tip of the neck heel over time and make the guitar fret out in the extreme higher register. Flatsawn necks (structurally weaker due to the grain orientation as it pertains to string tension) and/or necks made of a soft spongy wood species are more vulnerable to the tip lift. I found this diagram that shows what I'm talking about to help what I'm saying make sense. But NEVER use a partial shim as thick as in this diagram. That would hump ANY neck regardless of saw cut or species over time.  If you need THAT much, pitch correction, use full pocket shims like the StewMac shims, or (ideally) recut the neck pocket at the optimum angle.

[sonic1974]

1 hour ago, Jeff R said:

Addressing Nathan's confusion ...

Shimming is absolutely necessary in many cases if you expect superior set-up results, for the reasons stated earlier in the thread. I've found factory shims in grail-era pre-CBS Fenders (material ranging from pickup flatwork to business card stock to even a tear-off from a cigarette pack packaging), and in the pockets of some really high end superstrats. As stated above, tremolos and the desired rate of pull/drop, especially if extreme, are a frequent catalyst. 

A partial pocket shim - aka a sliver of material that only covers 1/5 or 1/4 of the bridge side of the pocket - can actually lift the tip of the neck heel over time and make the guitar fret out in the extreme higher register. Flatsawn necks (structurally weaker due to the grain orientation as it pertains to string tension) and/or necks made of a soft spongy wood species are more vulnerable to the tip lift. I found this diagram that shows what I'm talking about to help what I'm saying make sense. But NEVER use a partial shim as thick as in this diagram. That would hump ANY neck regardless of saw cut or species over time.  If you need THAT much, pitch correction, use full pocket shims like the StewMac shims, or (ideally) recut the neck pocket at the optimum angle.

 

So I think I'm showing my ignorance of the mechanics of guitar building, when I admit that when I think of needing a shim, that it means to me something is wrong with the guitar. 

 

Is it because of the nature of Fender style guitars, the neck and the body being made separately, and then just put together at the end? Or for instance, if you had a neck and body purpose build to match each other, would that negate any need for a shim? 

 

Just trying to understand this whole shim business! haha

 

[Dave Scepter]

I've even used wooden door shims before... sand lightly, put 2 together then then trim to fit

[stonge]

I have used the StewMac shims on a couple of different guitars and basses with good results.  I had a EVH star where the action around the 18th fret was about .060 off the fingerboard so I dropped in a 1/2 degree shim that dropped the action back down to .030 or so and made it easier to play (I put the fat side toward the body and the headstock kicked back enough to fix the action).

Mass-produced bolt-ons are all manufactured to tolerances on the neck routing, neck thickness and there are a range of combos that would cause different angles in the bridge/body/neck/string geometry.  A good luthier would be tweaking the build for playability, but some guitars are just assembled with minor tweakage (as long as they hit basic parameters they are shippable but not optimized for the best possible action).

Another case I'm finding to be unfortunately common is that 80's bolt-on shredders tend to have a little settling between the bridge/locking nut/neck joint.  I usually have to shim the locking nut base to get the strings over the first fret due to settling of the base.  The neck angle can also change a little (cranking down hard of the bolts could be compressing either the neck or the material in the neck pocket).  I've got a Washburn N4 where the neck has settled and the fingerboard points right at the neck pickup so the action above the 12fret is great for slide but not much else.  That's going to be a fun fix since the Stephens cutaway uses a very different geometry for the neck pocket so getting that headstock to kick back will be interesting...

[Nathan of Brainfertilizer Fame]

8 hours ago, Jeff R said:

Addressing Nathan's confusion ...

Shimming is absolutely necessary in many cases if you expect superior set-up results, for the reasons stated earlier in the thread. I've found factory shims in grail-era pre-CBS Fenders (material ranging from pickup flatwork to business card stock to even a tear-off from a cigarette pack packaging), and in the pockets of some really high end superstrats. As stated above, tremolos and the desired rate of pull/drop, especially if extreme, are a frequent catalyst. 

A partial pocket shim - aka a sliver of material that only covers 1/5 or 1/4 of the bridge side of the pocket - can actually lift the tip of the neck heel over time and make the guitar fret out in the extreme higher register. Flatsawn necks (structurally weaker due to the grain orientation as it pertains to string tension) and/or necks made of a soft spongy wood species are more vulnerable to the tip lift. I found this diagram that shows what I'm talking about to help what I'm saying make sense. But NEVER use a partial shim as thick as in this diagram. That would hump ANY neck regardless of saw cut or species over time.  If you need THAT much, pitch correction, use full pocket shims like the StewMac shims, or (ideally) recut the neck pocket at the optimum angle.

that's very clear now

[Jeff R]

Here's another "a shim will fix it" example ... if protruding saddle height screws are annoyingly digging into your hand.

My daily go-to superstrat is set up perfectly with no shims. I love it just like it is. I like the position of the plate in relation to the body, the "just enough" up pull from the bar, so I don't want to lower the plate any closer to the face of the body.

The saddle height screws protrude, however, and they stick out enough to annoy some more finicky players who play my guitar. Since I build and sell guitars like this, I have to have a solution. And fast, no cost, unobtrusive and easy to reverse solutions are always preferred.

Move the plate closer to the body and raise the saddles? I already said I don't want to do that.

Get shorter screws? Maybe, but it's difficult to source the Gotoh 510's saddles' M3 thread hex grub screws that are less than 6mm in length.

Grind the screws shorter? I can, sure, but for this post's and DIY purposes, not everyone has a bench grinder.

If I put a shim the thickness of a thick-stock business card in the pocket, however, I'll have to raise each saddle a mm or two to get my action back where it was. Doing that will submerge the protruding screws.

Protruding saddle screws ...

Bridge is perfectly positioned and floated for my tastes.

Arrows show where and how neck pitch will change, and how saddles need to move.

[Nathan of Brainfertilizer Fame]

On 9/28/2022 at 9:21 AM, Jeff R said:

Addressing Nathan's confusion ...

Shimming is absolutely necessary in many cases if you expect superior set-up results, for the reasons stated earlier in the thread. I've found factory shims in grail-era pre-CBS Fenders (material ranging from pickup flatwork to business card stock to even a tear-off from a cigarette pack packaging), and in the pockets of some really high end superstrats. As stated above, tremolos and the desired rate of pull/drop, especially if extreme, are a frequent catalyst. 

A partial pocket shim - aka a sliver of material that only covers 1/5 or 1/4 of the bridge side of the pocket - can actually lift the tip of the neck heel over time and make the guitar fret out in the extreme higher register. Flatsawn necks (structurally weaker due to the grain orientation as it pertains to string tension) and/or necks made of a soft spongy wood species are more vulnerable to the tip lift. I found this diagram that shows what I'm talking about to help what I'm saying make sense. But NEVER use a partial shim as thick as in this diagram. That would hump ANY neck regardless of saw cut or species over time.  If you need THAT much, pitch correction, use full pocket shims like the StewMac shims, or (ideally) recut the neck pocket at the optimum angle.

This helped ensure I didn't make a potential mistake by buying these:

https://reverb.com/item/41504743-guitar-neck-brass-shim-plates-for-electric-guitars-neck-angle-pitch-optimum-tone-and-sustain

Thanks!

[Nathan of Brainfertilizer Fame]

On 9/30/2022 at 9:28 AM, Jeff R said:

Here's another "a shim will fix it" example ... if protruding saddle height screws are annoyingly digging into your hand.

My daily go-to superstrat is set up perfectly with no shims. I love it just like it is. I like the position of the plate in relation to the body, the "just enough" up pull from the bar, so I don't want to lower the plate any closer to the face of the body.

The saddle height screws protrude, however, and they stick out enough to annoy some more finicky players who play my guitar. Since I build and sell guitars like this, I have to have a solution. And fast, no cost, unobtrusive and easy to reverse solutions are always preferred.

Move the plate closer to the body and raise the saddles? I already said I don't want to do that.

Get shorter screws? Maybe, but it's difficult to source the Gotoh 510's saddles' M3 thread hex grub screws that are less than 6mm in length.

Grind the screws shorter? I can, sure, but for this post's and DIY purposes, not everyone has a bench grinder.

If I put a shim the thickness of a thick-stock business card in the pocket, however, I'll have to raise each saddle a mm or two to get my action back where it was. Doing that will submerge the protruding screws.

Protruding saddle screws ...

Bridge is perfectly positioned and floated for my tastes.

Arrows show where and how neck pitch will change, and how saddles need to move.

So right now I have a warmoth neck exactly where I like it. Low action, no issues.  But I *think* the truss rod is near its max flex to get it there.

To try to be clear, when I just put the neck on the body, the action was too high. Turned the truss rod bolt (at the neck pocket treble side...modern construction) clockwise, and it improved.  Continued turning, it improved more. But there was decent resistance for the final turn that got it where the action is where I like it, but with no buzzes.

So I'm thinking I drop a .5 or 1 degree stew-mac shim in there, it lets me back off the truss rod a little bit.  Is that correct?

[kizanski]

4 minutes ago, Nathan of Brainfertilizer Fame said:

So right now I have a warmoth neck exactly where I like it. Low action, no issues.  But I *think* the truss rod is near its max flex to get it there.

To try to be clear, when I just put the neck on the body, the action was too high. Turned the truss rod bolt (at the neck pocket treble side...modern construction) clockwise, and it improved.  Continued turning, it improved more. But there was decent resistance for the final turn that got it where the action is where I like it, but with no buzzes.

So I'm thinking I drop a .5 or 1 degree stew-mac shim in there, it lets me back off the truss rod a little bit.  Is that correct?

Why add a shim to get the action back to where you already have it right now?

[Hbom]

27 minutes ago, Nathan of Brainfertilizer Fame said:

So right now I have a warmoth neck exactly where I like it. Low action, no issues.  But I *think* the truss rod is near its max flex to get it there.

To try to be clear, when I just put the neck on the body, the action was too high. Turned the truss rod bolt (at the neck pocket treble side...modern construction) clockwise, and it improved.  Continued turning, it improved more. But there was decent resistance for the final turn that got it where the action is where I like it, but with no buzzes.

So I'm thinking I drop a .5 or 1 degree stew-mac shim in there, it lets me back off the truss rod a little bit.  Is that correct?

Did you get the neck set flat(or slight up bow) with the heel adjustment before you put the neck on the body? IIRC that side adjuster is just for fine tuning. 

[Nathan of Brainfertilizer Fame]

1 hour ago, kizanski said:

Why add a shim to get the action back to where you already have it right now?

less tension on the rod

Assuming that is how i should be thinking

[Nathan of Brainfertilizer Fame]

1 hour ago, Hbom said:

Did you get the neck set flat(or slight up bow) with the heel adjustment before you put the neck on the body? IIRC that side adjuster is just for fine tuning. 

No.

So if I got where I want with just fine tuning, I'm good?

[Hbom]

52 minutes ago, Nathan of Brainfertilizer Fame said:

No.

So if I got where I want with just fine tuning, I'm good?

I'd say more like alright. You started the conversation asking about shimming. So sorta good. maybe not so good.

You will have to remove the neck to put in a shim. I would reset the truss rods to Warmoth specs and try again from there before I looked at shimming.

But I'd wait for Jeff R or someone else that REALLY knows to answer that.

 

 

[Jeff R]

 

So right now I have a warmoth neck exactly where I like it. Low action, no issues.  But I *think* the truss rod is near its max flex to get it there.

 

Whether the rod is maxxed out or not is a moot point. If you have it exactly where you want it, you succeeded.