Shimming/Setup question

[OshKoshJoash]

I've been trying to shim my 08 Am.St. Jazz, but I've been running into a few problems.

I first shimmed it because I couldn't set the action on the G string low enough. Thus, I cut out a 1/4'' shim from a business card, and its the width of the neck pocket. I placed it just like Gary Willis had it, at the bridge side of the neck pocket. http://garywillis.com/pages/archives...ask_jan00.html

I was surprised how big of a difference a tiny shim like that made! I was able to effectively get my action as low as I'd like. However, when fretting the 19th fret (2nd the last), I'd get buzz and the note won't ring very clearly, and the 18th fret is barely making it also.

I looked down the neck, and the relief in the neck made it look like at the last few frets, the neck went towards the string. It made sense why the last few frets would buzz. I think the shim, as small as it was, changed the neck angle too much.

I'm wondering what the remedy would be. Should I make the neck more flat by decreasing relief? Should I move the shim closer to the neck to decrease the change in angle?

Here's a diagram that will hopefully depict my issue a bit better.



Thanks for all your help!

[Turnaround]

Start by getting the neck relief right - somewhere between 10 and 15 thousandths, measured at the 7th or 8th fret. Then set the string height to your taste at the 12th fret. If you are careful and there aren't any other problems (such as a rising tongue or ski-jump) then it should work out fine.

[stflbn]

Generally...

"buzzing by the nut 1 thru 4th frets = neck to flat and strings to low"
"buzzing at highest notes on neck means strings to low for how much relief is currently set in the neck"

At least that's my current ongoing understanding. The only time I shim a neck is if I want all the strings lower and the bridge will not allow any more lowering.


The other thing to keep in mind is you may have some high frets up high on your neck that's increasing the problem.


A fret-rocker from StewMac.com is a valuable little tool for quickly checking for high frets.

[JustDavid]

I've got a similar issue on a fretless I'm working on. Saddles hit bottom, so shimmed & think I might have over-shimmed.

I want to make sure I understand what you've said. I measure neck relief by capo'ing at the 1st fret, fretting the last fret, & measuring fret/string gap at the 9th fret. With all strings tuned, work the truss rod to get 10 to 15 thousands of an inch?

[OshKoshJoash]

an update:

i used a thinner shim (a piece of magazine cover) instead of the business card, and it helped. from there i made the neck a bit flatter. i don't have calipers or anything that precise, so everything had to be done by feel.

now it's set up perfectly! i've learned that a thin shim goes a LONG way and it does more than you'd expect.

[unclejane]

Originally Posted by OshKoshJoash

I've been trying to shim my 08 Am.St. Jazz, but I've been running into a few problems.

I first shimmed it because I couldn't set the action on the G string low enough. Thus, I cut out a 1/4'' shim from a business card, and its the width of the neck pocket. I placed it just like Gary Willis had it, at the bridge side of the neck pocket. http://garywillis.com/pages/archives...ask_jan00.html

I was surprised how big of a difference a tiny shim like that made! I was able to effectively get my action as low as I'd like. However, when fretting the 19th fret (2nd the last), I'd get buzz and the note won't ring very clearly, and the 18th fret is barely making it also.

I looked down the neck, and the relief in the neck made it look like at the last few frets, the neck went towards the string. It made sense why the last few frets would buzz. I think the shim, as small as it was, changed the neck angle too much.

I'm wondering what the remedy would be. Should I make the neck more flat by decreasing relief? Should I move the shim closer to the neck to decrease the change in angle?

Here's a diagram that will hopefully depict my issue a bit better.



Thanks for all your help!

Have you thought about simply deepening the groove in the G saddle instead?

That was what I did on my G&L's, both of which needed to go lower on the G. Grinding into a replaceable saddle is far preferable to trying to shim the neck and get all that stuff out of alignment, IMO....

LS

[Turnaround]

Originally Posted by JustDavid

I've got a similar issue on a fretless I'm working on. Saddles hit bottom, so shimmed & think I might have over-shimmed.

I want to make sure I understand what you've said. I measure neck relief by capo'ing at the 1st fret, fretting the last fret, & measuring fret/string gap at the 9th fret. With all strings tuned, work the truss rod to get 10 to 15 thousands of an inch?

That's the idea. Depending on your playing technique, you may need a bit more or less relief. 10 to 15 thou is a good starting point. I would go with that then see if you are still getting some buzz. If it occurs only on the lower frets (nearer the nut) and not above the 12th fret, you might need a bit nmore relief. If it buzzes pretty well all over the fingerboard, you probably need to raise the strings at the bridge saddles. If you are getting buzz only above the 12th fret, you could try raising the string height a bit - or you may have a bit of a rise in the fingerboard at the body joint.

Go with 15 thou relief for a start and see how it goes.

Oh, and don't do anything with the nut at this point. We first need to find out what's happening when the relief is right.

[OshKoshJoash]

if you look a few posts up, i just had to use a thinner shim and adjust the relief a little bit. its perfect now! i realized that there was too much relief and the shim was just too big.

[JustDavid]

Nut seems fine. There I'm using this methodology:
1/ Get the bass somewhat setup
2/ fret a note & measure string/fret gap at next bridgeward fret
3/ open string & measure string/fret gap at 1st fret
4/ nut should be adjusted to have 3's measurement equal 2's. Perhaps a bit greater (paranoia dependant)

Thanks!!! Off to the tools . . .

[pickles]

The only thing the shim changes is the height the saddles need to be at to achieve the same action. The situation you found yourself in was that you had too much relief and too low of saddles. You should make sure to get the relief right first in any setup (certainly before you start shimming).

[JustDavid]

Relief now around 0.3 mm. Adjusted saddle heights to even out the mwaah-ish sound up & down the fingerboard.

Nut height is now disportionate but about 0.23 mm & quite playable. I'll see what the end user thinks.



Feels very nice!! Thanks!!!!!