To shim or not to shim Jazzmaster?

[beefyburt]

I've just bought a American Proffesional Jazzmaster, and seen a lot of talk about adding a shim to make the neck relief better. Whats the latest theory on this? Do, do not? If do, can I do it myself with some old credit cards? Add just to the bottom of the pocket? Or just ignore all the chatter?
Cheers.

[manwithtitties]

cant you just change the neck angle with the micro-tilt thing on the back of an ampro guitar?

[adamrobertt]

I've just bought a American Proffesional Jazzmaster, and seen a lot of talk about adding a shim to make the neck relief better. Whats the latest theory on this? Do, do not? If do, can I do it myself with some old credit cards? Add just to the bottom of the pocket? Or just ignore all the chatter?
Cheers.

Shimming has nothing to do with relief, that's controlled by the truss rod. Shimming a neck is done to increase the neck angle, effectively lowering the nut and raising the heel of the neck. This lets you raise the bridge a bit higher for more string tension while still having a low action. As far as I know, though, these guitar already have an angled neck pocket. Shimming is DEFINITELY worth it on a Jazzmaster, but I have a feeling that your guitar may already be set up in a way that it isn't necessary. How high is your bridge off of the guard?

And yeah, I think these guitars have a built in neck angle adjustment anyway. There's a hole in the base of the neck plate for a tool to go in (probably an allen wrench) that lets you turn a screw that raises the neck at the heel. So if adjustment is needed I'd do it that way.

[algeriet]

My 0.02€:

Like Adam wrote above; it has nothing to do with relief, but to increase neck angle.
I would personally never put a small piece of paper, pick etc on one end as this can create a hump in the fretboard/neck after long periods of pressure and thus you will need to remove fretboard wood to get it all aligned again. Did/do Fender do this? Yes. My '64 Mustang had a small piece of sandpaper on the end and that guitar had no issue, but then again it was refretted before I got it so who knows.

Here's an example of that:
https://www.youtube.com/watch?v=bga0UPM61cc

Regarding the micro-tilt, it's sort of the same idea as applying a small piece of scrap in one corner: eventually the wood will try to press itself down and you will most likely receive the same results as above. I have zero first hand experience with using the micro-tilt as exactly every luthier I've discussed it with has dissuaded me from using it.

I suggest a neck shim that covers the entire base of the neck heel/pocket. Either you make one yourself or you order them from StewMac:
https://www.youtube.com/watch?v=kIUzd0IjchU

On two of my modern Jazzmasters (AO60's and AV65), both with angled neck pockets from the factory, I've needed to shim the neck to raise the bridge so the E strings' ball ends don't come in contact with the two screws on the outer ends of the vibrato. YMMV.

[mortron]

Use wood shims... Not credit cards... Those are for buying more guitars you don't need... It'd be a pain in the ass to take your neck off everytime you get GAS. May help you avoid spending $ tho.

To be honest, shimming material isn't anything I gave more consideration to untill getting into offsets. I used slices of card stock and the like... Just like Uncle Leo did. That's not to say it's the right thing, and I never go crazy with it. Little bits go long way, because as pointed out, neck angle and relief are different. If you can't get things playing nice with all the parts on the guitar, then add more. It was supposed to be okay with the parts it came with... But world isn't perfect.

Reality is that creating a tiny gap in there can't be good for transmitting vibration, and some have mentioned it can let moisture into a potentially under finished neck pocket. With the micro Tilt, I see it just exasperating that problem of creating a gap. Maybe the micro tilt doesn't have that much range... I can't see how balancing one end of the neck pocket on a screw is better than wood resting on wood. Which is why I am not keen on just shoving crap in there. In HiFi they put things on metal spikes to drain vibrations away from a device... I always saw the microtilt as doing a similar thing as a byproduct of its design. Obviously this can't be the case because plenty of folk enjoy them and that would be a big deal. It's more comfort and peace of mind personally.

The Stew Mac shims are smart in sense they're accurate enough to get precision angles. My buddy said he couldn't even cuz them on a table saw that precise. I figured they were sanded and not cut, he figures for the $ and precision, that StewMac is still the way to go. What you get is wood on wood. Vibrations travelling through wood instead of air. $10 for tone is never a bad thing. Put it on that credit card you didn't jam into the wrong (neck) pocket.

[Larsongs]

If your Offset requires a Shim to get the proper Neck angle you desire for the Set up you want. Yes.

One of my Offsets needed a Shim.. My Luthier Custom made it of the same Wood as the Body. Cut, Sized & Angled as though it were the actual Body.

Not all Shims are the same..

Do all Offsets need Shims? No.

[Larry Mal]

I shim all my Fenders by default, but: some modern Jazzmasters have angled neck pockets now. I forget which models, though.

A full length shim is much preferred. Granted, what Old Leo did worked also, but over the years it led to something called the "ski jump".

It is a catastrophic problem for a neck to have, so avoid that.

[LVC]

If it ain't broke, don't fix it.

[gnoleb]

I've just bought a American Proffesional Jazzmaster, and seen a lot of talk about adding a shim to make the neck relief better. Whats the latest theory on this? Do, do not? If do, can I do it myself with some old credit cards? Add just to the bottom of the pocket? Or just ignore all the chatter?
Cheers.

And yeah, I think these guitars have a built in neck angle adjustment anyway. There's a hole in the base of the neck plate for a tool to go in (probably an allen wrench) that lets you turn a screw that raises the neck at the heel. So if adjustment is needed I'd do it that way.

This is correct. Your guitar has that micro tilt feature. You do not need a shim. There are videos online (even from Fender) that show how to use it, but any good tech will also know.

[Larry Mal]

It's much better to use a shim than the Micro-tilt, though. I think I linked above to the phenomenon of the "ski jump" that can be done with half-assing it by using a cut up credit card, well, the Micro-tilt does the same thing. It's built in but it's no better.

If you don't have an angled pocket, then a shim is the only good alternative.

[timtam]

I have always thought that the Microtilt was one of Fender's worst ideas. On top of being a very questionable way to achieve tilt (by creating a gap in the neck pocket, sitting on one screw end), it is a PITA trying to mate necks and bodies when one has it and the other doesn't. The original 3-bolt style is the worst in that regard ... at least the newer 4-bolt microtilt is inter-changeable with necks/bodies that don't have it (but still a PITA if you want to add it to either ... simple solution ... don't).

Its only use to my mind is to test out neck angle changes easily, and then if that works .... get a proper tapered full pocket shim for a permanent solution.

But as others have said, if your JM is functioning well as is (bridge, trem), there is no need to mess with it.

[gnoleb]

It's much better to use a shim than the Micro-tilt, though. I think I linked above to the phenomenon of the "ski jump" that can be done with half-assing it by using a cut up credit card, well, the Micro-tilt does the same thing. It's built in but it's no better.

If you don't have an angled pocket, then a shim is the only good alternative.

I can't speak with knowledge that I actually know that it is better, but I can say that I've had two different guitar techs at the renowned Truetone in Santa Monica tell me that shims are bad for tone and stability. And that Leo Fender himself designed the micro-tilt for Fender and carried it on to G&L.

Again, I can't prove anything. But it makes me wonder if a super cheap piece of small angled wood was better that the obviously more expensive tooling to do the micro-tilt...would it still exist after decades? I dunno.

If you have some source showing shims are better than micro-tilt, I'd love to see/read/hear it.

[timtam]

It's much better to use a shim than the Micro-tilt, though. I think I linked above to the phenomenon of the "ski jump" that can be done with half-assing it by using a cut up credit card, well, the Micro-tilt does the same thing. It's built in but it's no better.

If you don't have an angled pocket, then a shim is the only good alternative.

I can't speak with knowledge that I actually know that it is better, but I can say that I've had two different guitar techs at the renowned Truetone in Santa Monica tell me that shims are bad for tone and stability. And that Leo Fender himself designed the micro-tilt for Fender and carried it on to G&L.

Again, I can't prove anything. But it makes me wonder if a super cheap piece of small angled wood was better that the obviously more expensive tooling to do the micro-tilt...would it still exist after decades? I dunno.

If you have some source showing shims are better than micro-tilt, I'd love to see/read/hear it.

Fair points. But sometimes asking a great tech about guitar physics is like asking a formula one driver about how his engine works. Great techs/builders are master craftsmen, not engineers. I've heard great builders say that on some issues (eg solid body 'tonewoods') they were just repeating the 'conventional wisdom' they had read/heard .. which they eventually realized didn't hold any water.

And if shims are bad for 'tone' and 'stability', it's hard to see that microtilts avoid those problems. Leo's arguments against shims (ie the thin strips of sandpaper used then) in the 1969 microtilt patent were that they were "laborious to employ in the factory and ... difficult for the guitarist to adjust inclination of the neck when desired". Of course part of the reason was also that Fender's manufacturing processes were not precise enough to produce the same neck angle every time (Gibson by comparison actually measure / tool each neck joint's wood to get the neck angle within the acceptable range).
https://patents.google.com/patent/US3550496


The 3-bolt style microtilt is a small grub screw to do the tilt (#46 above), and two metal plates screwed into the wood, with a machine screw as the 3rd bolt pulling the two together and holding the neck in place. The newer 4-bolt style microtilt is a bigger screw, the end of which sits against the metal truss rod anchor. So not exactly expensive tooling.



Certainly there are reasons for suspecting Fender's original strips of sandpaper shims were less than ideal. Tech Gerry Haze's link from above has a nice discussion of the potential ski jump issue. It's hard to see that the inherent gap/limited contact points of the Microtilt avoids this danger.
https://hazeguitars.com/blog/neck-shimm ... t-research

But regarding hard evidence ... even the stock-standard conventional neck joint styles' (bolt on, glued) 'role' in the guitar's sonic function has little hard evidence to support the effects / superiority of any approach. Some suppositions regarding which is best don't seem to stand up to scrutiny, and some further evidence suggests that no conventional fully-closed neck joint is clamped/glued sufficiently strongly to avoid micromotion/string vibration losses ...
https://www.liutaiomottola.com/PrevPubs ... ustain.htm
https://www.researchgate.net/publicatio ... ric_Guitar
https://www.youtube.com/watch?v=6wAbGFz8oEQ

So at the end of the day we don't have hard evidence against the microtilt ... it's just semi-educated reasoning that suggests a full pocket tapered (wood) shim is better than a microtilt where the raised end of the neck pocket sits on the end of a single bolt creating a gap in the neck joint.

[Larry Mal]

I can't speak with knowledge that I actually know that it is better, but I can say that I've had two different guitar techs at the renowned Truetone in Santa Monica tell me that shims are bad for tone and stability. And that Leo Fender himself designed the micro-tilt for Fender and carried it on to G&L.

Again, I can't prove anything. But it makes me wonder if a super cheap piece of small angled wood was better that the obviously more expensive tooling to do the micro-tilt...would it still exist after decades? I dunno.

If you have some source showing shims are better than micro-tilt, I'd love to see/read/hear it.

I'm unaware that there's been any kind of scientifically rigorous study I'll be able to point to here, I doubt it's been researched well enough for that. So, if you want to believe otherwise, go right ahead- it's your guitar.

That being said, though, you don't say what kind of shims your two different techs were warning against. Were they telling you that a wooden, full length and full contact shim was bad for tone and stability? Or that other common shimming techniques like a length of credit card or a guitar pick were the problem?

While I'm not going to bother with trying to find scientifically rigorous research here, it doesn't take a huge stretch of the imagination to think that a piece of metal pushing up on a piece of wood which is under quite a lot of pressure from the guitar strings is very likely to warp over the course of decades. It's still wood, after all.

The whole point of the full contact shim is to eliminate the singular pressure point of a Micro-Tilt or a bad shim, and to spread the pressure all around. Even then, you'll still have the fact of the pressure of the guitar strings which will in time warp the wood of the neck in and of themselves- that's why doing a neck reset on an acoustic guitar is a common thing.

I'm not sure what is hard to imagine here. It was immediately clear to me what force would do to a piece of wood in a situation like this. The only way to think that it would not happen is to somehow have the belief that the object that the force is being applied to was so strong that the force would not affect it, but we are discussing a piece of wood here, you know?

A piece of wood that is so subject to the forces applied to it in tandem with the environmental factors that occur that literally every guitar neck has a metal rod running down the length of it in order to adjust it otherwise it would warp and become useless very quickly.

Are we to think that taking a piece of metal and jamming it up under there won't over time make an unwanted change? And if we can't imagine that, well, we know that the "ski jump" phenomenon does happen. Why does it happen, if it doesn't happen because of the forces applied to it?

[Larry Mal]

I will thrown another article out there, though.

Maybe it'll help someone understand. Again, though, if you don't want to believe it, it's your guitar.

Incidentally, though, the Micro-tilt might have been Leo Fender's way of being able to get guitars out the door quickly. Remember that mass produced electric guitar makers came up with a few concepts that just allowed them to have a lot of slop in the construction more than anything else.

The whole bolt on neck is a way of making guitars cheaper in the first place, right? The traditional set neck method if done right eliminates all these issues but it takes time and skill of labor.