Full pocket vs partial shim

[Turnaround]

There is an opinion that states they do create ski-jumps. See here.

Jerry and I disagree on this. As I have stated in the past, I don't believe I have ever run into a case where a shim has caused distortion to the neck heel as Jerry describes. And I have seen hundreds of ski jumps over the decades that I have been repairing instruments. The distortion is outboard of the neck pocket, so a shim cannot be the cause of the ski jump. And I have a long-term experiment underway to see if I can induce a ski jump in the neck pocket. It has been over 3 years now and there is no distortion. It is easy to mistake the location of the distortion as I will demonstrate later - I need to take some pics to illustrate. Stay tuned.

 

[smtp4me]

So to get the answer, there’s probably no difference in sound between the two right? I’d imagine that if it’s shimmed it’s shimmed. Luthier believes partial shims create ski jumps, the bass I have has strong magnets and can’t be played above the 12th fret anyways so I’m not worried, you hear a lot of music with partial shims and never notice but full pocket shims are new, what do you think. Little frustrated that they did a full pocket instead of a partial but I’m not really mad and probably don’t know as much as them, just seeing if the shim either partial or full makes any difference, honestly might just take it out and microtilt it

I'm not an expert, but my understanding is that a full-pocket shim is better - because you don't want any gaps between the neck heel and the neck pocket. If there are gaps, you can lose resonance.

 

[TrevorR]

Interesting discussion in a way and I agree with other comments that the OP is a bit overthinking the shim issue - and maybe basing that overthinking on a misunderstanding of what's going on.

The comments about preferring a partial shim to get more original wood contact make no sense to me as the partial shim would pretty much ensure a "big" air gap in the neck pocket between the places where the neck makes contact with the body and the shim - so LESS contact overall. I guess that this is where the luthier's concerns on the ski jump come from as the neck bolts might pull the neck down to fill the gap, bending the end of the neck into a curve. I've seen that argued by several guitar builders/fixers... For example.

...is that true or not... no idea but it sort of seems a bit plausible, sort of...

My personal preference based only on snake oil, mojo and an understanding of secondary school physics would push me towards a full pocket shim as that should maximise the wood on wood on wood contact area with vibrations being able to pass relatively unimpeded across the whole of the neck body joint and that FEELS more logical to me than a neck joint where vibrations are being transferred across two separate areas with an air gap in between.

Photos from a similar Google search showing the difference between a partial and full pocket shim - for avoidance of doubt...

So on a personal basis (and as the above caveat says, on the basis of personal preference and presumption) my leaning would be to a full pocket shim - and I know many, many, many very well respected luthiers prefer to shim that way so it's by no means an "inferior" solution like the OP presumes (and of course a similar number happen to prefer a partial - no biggie!).

So, yes, we're definitely in the way overthinking it territory by the OP. So if the neck angle is now such that the magnets can be adjusted to stop magnetic interference and wolf tones I'd probably say that the OP should be pleased with a job well done and stop worrying about a "problem" which they seem to have invented in their own mind.

 

[-Asdfgh-]

Full pocket shim for me if the neck relief/angle is good to go other than needing lower action. A partial shim introduces a new angle, a shim in the lower pocket tilts the neck backwards a shim in the upper part of the pocket tilts the neck forward so to speak.

I do not like the saddle screws to claw at my hand (muting) so if I can't get the action as low as I like without the screws being very close to flush (in the saddles) I use a full pocket shim. Good luck.

I need to put a shim back in one of my basses. Plays fine, the issue is the saddle screws. Unless I can find some really short screws.

 

[mongo2]

For a few decades, when I need a shim, I've used strips of masking tape applied to the bottom of the neck heel in a stairstep fashion to create a wedge. It has never changed the tone or created any other isssues and it's very easy to do.

With the tape I can also easily make a reverse shim which, while it doesn't cure it, can help put a bass with a ski jump back onto playing condition with acceptable action. That's worked for me a few times but some jumps might too extreme for the shim to help.

I've also used flat shims made of tape or wood when necessary.

 

[Gunga Din]

Jerry and I disagree on this. As I have stated in the past, I don't believe I have ever run into a case where a shim has caused distortion to the neck heel as Jerry describes. And I have seen hundreds of ski jumps over the decades that I have been repairing instruments. The distortion is outboard of the neck pocket, so a shim cannot be the cause of the ski jump. And I have a long-term experiment underway to see if I can induce a ski jump in the neck pocket. It has been over 3 years now and there is no distortion. It is easy to mistake the location of the distortion as I will demonstrate later - I need to take some pics to illustrate. Stay tuned.

Thanks. I have a vested interest as I have a Telecaster that's exhibiting this.

Additionally, what are your views on the cause?

 

[C Stone]

I have seen "ski jumps" on occasion that were (IMO) either from weaker neck wood? or possibly when at the butt end of the neck because the truss rod does not extend the total length of the neck (stops short of the butt end) but more often said "ski jump" is more of a jut upwards in the area of the 13-14 fret and if you think about it it makes sense that is where the pressure would be right where the neck thins out.

 

[baxter_x]

I did shim my Sadowsky MV5 last year with a piece of credit card.
There is not a single little thing that has changed tonewise when I play the bass.

 

[baxter_x]

The comments about preferring a partial shim to get more original wood contact make no sense to me as the partial shim would pretty much ensure a "big" air gap in the neck pocket between the places where the neck makes contact with the body and the shim - so LESS contact overall.

To me that is a complete voodoo thing. I wish I could find that video where Roger Sadowsky and Mickeal Tobias both talk about shimming and totally demystifying it. It's from 2013.

 

[TrevorR]

To me that is a complete voodoo thing. I wish I could find that video where Roger Sadowsky and Mickeal Tobias both talk about shimming and totally demystifying it. It's from 2013.

The guitar/bass world isn't short on voodoo. It must be all the snake oil that's used to season the tonewoods...

 

[Lowbrow]

Voted 'not noticeable,' which I believe to be true and a long-followed best practice by reputable luthiers the world over. However, when doing my own shimming I've opted for StewMac full-pocket despite their outrageous expense simply because I'm anal and dig their precision. It's a good marketing ploy on their part ... with the shims' varying thicknesses, you are bound to buy more than one!

 

[Turnaround]

You often see this kind of an illustration of a ski jump:

It looks like the tail end of the neck is rising. But that's not what's happening - the area of the neck around the 12th fret has a kink raising the nut end of the neck. So when you lay a straightedge along the fretboard the part of the neck before the 12th fret is lifting the staightedge creating the gap you see.

Here is a neck with a ski jump. With a straightedge on the back of the neck you can see that the last 2 inches or so of the neck heel seems to be deformed (a ski jump seen from the back side of the neck).

You can see from the 13" to 15" mark a triangle of light between the straightedge and neck heel - about 2 inches long (the heel is about 4" long). The gap at the end of the heel is about 1/16".
However, this is a false reading. The actual kink is on the neck between the 12th and 14th fret. If I lay the straightedge on the heel instead of on the main part of the neck, you can see that the heel is actually flat:

Since a shim is placed in the pocket where the heel rests, it is pretty clear that the shim was not the cause of the ski jump since the ski jump was outboard of the pocket. In all the cases where I have dealt with a ski jump, I have yet to find one that actually had a bend in the heel.

 

[azureblue]

It’s an old musicman, so one of the reason the early l2000 g&ls moved the pickups from the sabres position to a closer position, and one of the reasons that the ernie ball sabres changed the neck pole pieces to 16 small ones rather than 8 big ones is because the pull of the magnets would interfere with the string vibrations causing a warble on the upper registers of the neck, now I’m fine with this because I don’t play that high up on the neck, and the tone is second to none. If you back up the pickups a ton, you might be able to play up to the 16th without any chorus sound, since I use string mutes and those kill the sustain the higher up on the neck you go anyways, it isn’t a dealbreaker for me. I’m fairly sure the 2h stingrays use deeper pickup cavity’s or it’s a problem with the minihumbuckers of the sabre


So for me, risking a ski slope that would make the highest six frets harder to play isn’t too much of a concern anyways

I had one and you are right - the pole pieces were really strong, and the design put them too close to the strings. Murder on light gauge round wounds. My tech started with a partial shim, which tilted the neck back, but we decided to fix the design flaw properly by putting a full pocket shim - actually glued to the back of the neck. He micro planed both the back of the neck shim and the pocket to get full contact and the exact height. We had to fiddle with the bridge a bit, too, but it was worth it.

 

[truand85]

Jerry and I disagree on this. As I have stated in the past, I don't believe I have ever run into a case where a shim has caused distortion to the neck heel as Jerry describes. And I have seen hundreds of ski jumps over the decades that I have been repairing instruments. The distortion is outboard of the neck pocket, so a shim cannot be the cause of the ski jump. And I have a long-term experiment underway to see if I can induce a ski jump in the neck pocket. It has been over 3 years now and there is no distortion. It is easy to mistake the location of the distortion as I will demonstrate later - I need to take some pics to illustrate. Stay tuned.

Gotta love TalkBass. Thanks for chiming in with actual expertise. Subbed for pics.

 

[Mike Marshall]

So to get the answer, there’s probably no difference in sound between the two right? I’d imagine that if it’s shimmed it’s shimmed. Luthier believes partial shims create ski jumps, the bass I have has strong magnets and can’t be played above the 12th fret anyways so I’m not worried, you hear a lot of music with partial shims and never notice but full pocket shims are new, what do you think. Little frustrated that they did a full pocket instead of a partial but I’m not really mad and probably don’t know as much as them, just seeing if the shim either partial or full makes any difference, honestly might just take it out and microtilt it

I have used full shims from Stew Mac with great results at a certain point a full shim is better in my opinion. I had amid 60's P Bass and my luthier planed the finger board past the 12th fret and the bass was perfect.

 

[Mrtoodamnsabre]

I had one and you are right - the pole pieces were really strong, and the design put them too close to the strings. Murder on light gauge round wounds. My tech started with a partial shim, which tilted the neck back, but we decided to fix the design flaw properly by putting a full pocket shim - actually glued to the back of the neck. He micro planed both the back of the neck shim and the pocket to get full contact and the exact height. We had to fiddle with the bridge a bit, too, but it was worth it.

It’s An amazing sounding bass, and I play with flats and actually am a big fan of the thumb mutes, I never really play above the 14th fret anyways, now and then I’ll get to 12, plus the mute kit chokes out the notes at around that point if the warbling starts there it’s no big deal to me, I bought this bass knowing this too, but I love the sound and it works for me! Someone who likes playing chords or very technical stuff up there in the octave isn’t gonna be too happy!

 

[GretschWretch]

Full pocket shim for me if the neck relief/angle is good to go other than needing lower action. A partial shim introduces a new angle, a shim in the lower pocket tilts the neck backwards a shim in the upper part of the pocket tilts the neck forward so to speak.

I do not like the saddle screws to claw at my hand (muting) so if I can't get the action as low as I like without the screws being very close to flush (in the saddles) I use a full pocket shim. Good luck.

 

[GretschWretch]

Interesting that whenever these shim discussions pop up, whether due to saddles bottomed out, overly magnetic pickups, or whatever, the solution is always to tilt the neck. Why not just raise the neck? Measure how much higher the neck has to be to solve the problem and use a flat, not triangular, full pocket shim of the desired thickness; i. e. a dead flat shim. This will raise the neck but also will keep the neck in the same plane as the rest of the instrument.

 

[jmlee]

I have used full shims from Stew Mac with great results at a certain point a full shim is better in my opinion. I had amid 60's P Bass and my luthier planed the finger board past the 12th fret and the bass was perfect.

I've found those Stew Mac shims very useful as well. They come in various angles and are pretty easily trimmed so that you have an induced tilt to the neck and full wood-to-wood contact. If the object is to simply elevate the neck without added tilt—a rare thing to need to do, I'd think—then hard wood veneer does the job. These Stew Mac shims are just that with a designed, linearly varying thickness. Nice product.

 

[C Stone]

View attachment 4634290

Thanks GW just not a fan, don't get me wrong, I can adjust and I have a couple covers on P basses as well as Jazz but it's not natural for me and just feels strange when muting, it forces me to play more forward than I like and pick articulation/mute/feel changes, I even cheat a little by positioning the cover as far back as possible while still covering the bridge...