ShortScale.org

Not sure if a thread has ever covered this and it was mentioned in a previous thread so i thought i'd put some info here.

I personally like low action on a guitar but it can be a difficult process to get it right depending on the brand and model. This is for bolt-on neck guitars only of course.
Fender guitars are versatile on this kind of set-up, usually you can get the action super low but it does not always work so well with vintage radius as the notes can 'choke' on string bending due to the frets being higher in the centre of the board.

Shimming the neck seems to scare some folks and is also sometimes seen as a bodge job (it is reversible and can cause no damage if done correctly). But in theory this is no different to the 1970's Fender Micro-Tilt System and in the 1960's some Fender guitars came with a neck shim straight from the factory. Some may still even to this day as other brands do.

Micro-Tilt System


Why would you shim your guitar neck when you can change the height of your bridge or saddles?
Sometimes, that alone is not enough and you wont get the full potential of playability from your guitar.
Here is a diagram explaining the effect of a neck shim.


As the diagram shows, it wont correct neck relief issues. This is a different thing.

What would you use as a neck shim?
I've seen everything, seriously, from steel washers to off-cuts of ply veneer, cigarette packet card, plectrums... Theoretically they all do the job but something neat that is full width of the pocket seems the way to go. Like this factory made shim on the Ernie Ball guitar.


What thickness shim would you use?
Finding the balance between the shim and bridge/saddle adjustment usually requires only a thin shim. A piece of card maybe 0.05mm will change the neck angle more dramatically than you can imagine. The only time you would need to shim more is on a major modification like fitting a TOM on an old Fender.

What material should the shim be made of?
The industry uses plastic. DIY'ers seem to use card, however, some people say sandpaper/glasspaper works better as it grips the surface eliminating any friction or movement during resonating. As ridiculous as it sounds this makes sense. I once shimmed a CIJ Jaguar neck with Rizla card and it did not sound the same, i tried sandpaper which improved it. I'll leave that one there for the Cork Sniffers.

I hope someone finds this useful, many players dont get the full potential from their guitars and this isn't all about the Malmstainz either.

Great guide. Had a go on my CVs - Strat needs a slightly thinner shim but the Tele is spot. Nice low action with no buzz. If you do your own setups but have never tried shimming, give it a go.

EDIT: Did you mean 0.5mm instead of .05?

Fran wrote: in the 1960's some Fender guitars came with a neck shim straight from the factory. Some may still even to this day as other brands do.

AVRIs frequently have 'em. US Fender still use a micro-tilt styled jiggery on newer style instruments, so it's possible they don't cut neck pockets or heels with as exacting a precision as they once did on traditional 4-bolt joints for reissues.

My AV '57 Strat however, which has a perennially low-relief neck and the lowest, most flawless action of any Fender I've ever played, does not have a shim.

George wrote:EDIT: Did you mean 0.5mm instead of .05?

I did, thanks George i'll correct that.

What an awesomely timed thread! I am just about to go take the neck off my "new" Coronado II again and adjust the action down. I put .11s on the guitar which slightly raised the action due to the higher tension. I put a business card cut up in as a shim and the strings were touching the frets so I took it out. I think I made it too long so I am going to make it smaller and try again.

Coronados (as well as other arch-tops) often have angled neck pockets which adds to the fun of getting the action right.

The Coronado had a shim that doesn't seem to do much

I use card, usually from a packet of paracetamol or similar, and cut the edges to the same shape as the neck pocket, I also make sure its long enough to have the screw holes go through it.

Works for me.

Great 'how-to' Fran.

Brilliant thread fran, my JM was shimmed perfectly when I got it, I just need to work out how to do similar with my SG

Shim/Intonation question:

I put in the shim and it seems to have lowered the action exactly where I wanted to, but now the intonation on the low E string is very low. The intonation on the other strings seems okay.

Any ideas why the lower E intonation would drop like that?

my amazing JAGMASTER was shimmed using an american quarter. fucking ruled. i don't believe the hype about neck+body resonance. that thing fucking ruled. the ONLY issue i ever had with it is a dead spot on the high e string at the 11th fret or so.

taylornutt wrote:Shim/Intonation question:

I put in the shim and it seems to have lowered the action exactly where I wanted to, but now the intonation on the low E string is very low. The intonation on the other strings seems okay.

Any ideas why the lower E intonation would drop like that?

If its too low the string may not be oscillating enough (catching the frets) and giving you a wrong reading on your tuner. You could raise that particular saddle a little.
I always try to keep the lower strings that little bit higher due to their thickness.

Sloan wrote:my amazing JAGMASTER was shimmed using an american quarter

I'd expect no less dude

lorez wrote:need to work out how to do similar with my SG

All bridge and truss rod adjustments Chris. With set-necks you rely on the manufacturer a lot.

lorez wrote:I just need to work out how to do similar with my SG

Not related to shimming but I just remembered, on SG's and TOM/Tailpiece guitars i used to raise the tailpiece a little. It reduces the break angle over the bridge and loosens the tension of the strings which i thought made the guitar more pleasurable to play. May be worth a try

Quick question. How do I know when to stop shimming?

Your bridge or saddles will only allow you to shim so far and you need them to still be adjustable either way, not at their maximum height. Beyond that you would end up with the 22nd fret touching the strings. Another thing to consider is pickup height if you higher the strings too far.
I suppose you find the best balance in the end and on a well made guitar it is usually a minor adjustment.

When the strings touch the fretboard...

...But really, when the action is low enough. I tend to shim, tune, play, then shim again if needed

Fran wrote:

lorez wrote:I just need to work out how to do similar with my SG

Not related to shimming but I just remembered, on SG's and TOM/Tailpiece guitars i used to raise the tailpiece a little. It reduces the break angle over the bridge and loosens the tension of the strings which i thought made the guitar more pleasurable to play. May be worth a try

I was kidding about the shim I'll try the trick though, although at the moment I've no really issues with the SG although it could be a bit lower. I've some spare evenings coming up so I think I'll have a mess about with it then

Righto. I can't seem to get lower than standard fender action though (which is decent and an improvement I suppose). Do you guys go for the standard neck relief of 0.010" at 8th fret Or do you go straighter because of the shim?

lorez wrote:

Fran wrote:

lorez wrote:I just need to work out how to do similar with my SG

Not related to shimming but I just remembered, on SG's and TOM/Tailpiece guitars i used to raise the tailpiece a little. It reduces the break angle over the bridge and loosens the tension of the strings which i thought made the guitar more pleasurable to play. May be worth a try

I was kidding about the shim I'll try the trick though, although at the moment I've no really issues with the SG although it could be a bit lower. I've some spare evenings coming up so I think I'll have a mess about with it then

Chris, I've got superb results with SG's and Les Pauls however that was by meticulously paying attention to truss, Nut slots and saddlle slots, as well as some gentle fret leveling here and there. Much more involved but not as hard as folks think - just work in tiny increments. As one mate said "it's like it's brand new again" - obviously from a time when gibson didn't bodge their shit up

thanks dave, I might pick your brains at some point then

George wrote:Quick question. How do I know when to stop shimming?

When it begins to interfere with your personal relationships and/work.

George wrote:Righto. I can't seem to get lower than standard fender action though (which is decent and an improvement I suppose). Do you guys go for the standard neck relief of 0.010" at 8th fret Or do you go straighter because of the shim?

I go quite straight, maybe a dip of about 1.5mm around the 8th fret.