Sorry, they've been back with their owners for years, a couple for decades. I started doing it in the '70s.
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Shims: The lazy mans fix??
- Thread starter Kunekune
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Sorry, they've been back with their owners for years, a couple for decades. I started doing it in the '70s.
Mis-cue on my part. I was of the impression that at least one was in your personal stable. Thanks for the consideration, though.
Riis
I'm still utterly clueless as to where this idea of fixing a ski jump by shimming a neck/body joint came from? This is like curing a cold by prescribing a laxative - the treatment and the problem are just completely orthogonal and have nothing to do with each other.
One consequence can be that the action is too high at the heel even after doing everything you can with the truss rod to get the action where you want it. You can -ish, sort of, -ish try to help this by tilting the neck backwards, but you usually quickly discover this doesn't really help. I did this forever on my L2K, an older 3-bolt model with the "micro-tilt" adustment, but it was, predictably, a failure in the end.
In my experience so far, most of the time ski-jumps occur in that area between where the heel leaves the body and up to the 9th/10th fret area, somewhere in there, where the truss rod usually is less effective. I've seen this on my basses over and over and it's exasperating.
The only fix, I've found, is to put that sucker on the neck jig and go after it with a radius beam. There's just no other way to treat that that I've seen.
I did this the other day when I defretted my MP Jazz and the results are really spectacular. I can get the action lower and more consistent on it than even my Carvin unlined basses lol.
My G&L is probably going to get this treatment too once I get my hands a 12" radius beam...
LS
I don't know about anyone else but I got the idea from looking at the geometry of the neck and body. I was an engineering student at the time and shimming seemed like an workable option for a ski-jump.
I found this to be true and, as I mention previously, I will use a flat shim to raise the neck which closes the distance between the strings and fingerboard. As I also mentioned previously I've used this technique for up to moderate ski-jumps. Other measures must be used for necks in worse condition including replacement when necessary.
Again, the problem presented by a ski-jump is the concave fingerboard that can't be flattened out or set to a normal relief, not its height or tilt. So shimming still sounds a bit like an irrrelevant fix to me.
The only way to really fix it is to level the board itself, preferably under simulated string tension with the appropriate truss rod setting. OTOH, the price of the tools to do that fix can be prohibitive, especially if you really want to do it with the right tools. Eg. a neck jig, radius beam and, if it's a fretted bass, files and holy smokes.... it can cost as much as a decent bass to get properly outfitted. Don't ask me why I know that.
So yeah in that case, it may be cheaper overall to simply replace the entire neck...
Ski jumps are my nemesis I think since I've had so many basses that had them. I finally broke down a couple weeks ago and decided to invest in a toolset so I can finally fight this here ski-jump demon on my own lol.
I just did this on my MP Jazz when I defretted it and my L2K is finally sitting on the jig waiting for parts. It's had a jump in it since I bought it in 2000....
LS
There are rare instances where a ski jump is created at the end of the fingerboard by the original shim. If so, moving the shim to being in-between sets of screw holes may actually reverse the problem, as the screws will then tend to pull the neck heel back down into a convex shape. As I said earlier I've done just this and it actually did work. As I also said, it's sketchy.
Well, if the reader walks away with a clearer understanding of how & why they work, including suitable applications, then the discussion is worthwhile IMO. Problem is that the well-founded tech talk is diluted with anecdotal evidence which is sketchy at best.
Riis
And some of that "well-founded tech talk" is based on inexperience with at least one facet of the topic.
Perhaps, but I think it's better to pursue the _right_ fix for the problem rather than going with the duct tape/bailing wire from the start. Accurate diagnosis and properly targeted treatment is more likely to lead to a good, durable outcome. Duct tape and bailing wire works too, but usually you're better off, especially in the long term, by simply making a new bracket from scratch and doing it the right way.
And, BTW, that's spoken by a true duct tape/bailing wire user, so don't get me wrong - I love duct tape/bailing wire too.
LS
I'm still flabbergasted at finding this particular application of shims at all, personally. Maybe this is a subtlety of advanced luthiery that I've simply never encountered, but it just seems totally bizarre to me.
I've now got shims under the neck joints on both my bolt-neck basses but the application is definitely only raising the fingerboard to a proper position and has nothing to do with levelling the boards. That's where the unfortunately expensive radius beams and neck jig come in....
Maybe I'm just old-fashioned?
LS
Turnaround
Commercial User
Since this has turned into the "Shims as a Cause of Ski Jumps" debate, perhaps some definitions are in order.
SHIMS
There are two kinds of shims we are discussing, full-pocket and partial pocket. Within the full-pocket category there are flat shims and tapered ones. Regardless of the type, were are talking about a thin piece of some material placed between the neck and the body of the instrument in the neck pocket.
SKI JUMP
Let's try this for a definition - A ski jump is a rise in the fingerboard in the area of the neck pocket, roughly from the 15th or 16th fret to the bridge end of the fingerboard on a Fender-type instrument. If the rise is starting at, say, the 12th fret, it is not a ski jump by this definition. This is an important distinction since we are debating the effects of a shim in the neck pocket. What happens outside the pocket area is of no concern here.
If we are OK with the definitions, then let's carry on with the debate. For clarity of discussion I have included a simple graphic representing a cross section through the neck pocket. I don't think it needs much explanation.
As a first part of the discussion, can we rule out all full pocket shims as contributors to a ski jump? (i.e. both flat and tapered). If not, why not?
SHIMS
There are two kinds of shims we are discussing, full-pocket and partial pocket. Within the full-pocket category there are flat shims and tapered ones. Regardless of the type, were are talking about a thin piece of some material placed between the neck and the body of the instrument in the neck pocket.
SKI JUMP
Let's try this for a definition - A ski jump is a rise in the fingerboard in the area of the neck pocket, roughly from the 15th or 16th fret to the bridge end of the fingerboard on a Fender-type instrument. If the rise is starting at, say, the 12th fret, it is not a ski jump by this definition. This is an important distinction since we are debating the effects of a shim in the neck pocket. What happens outside the pocket area is of no concern here.
If we are OK with the definitions, then let's carry on with the debate. For clarity of discussion I have included a simple graphic representing a cross section through the neck pocket. I don't think it needs much explanation.
As a first part of the discussion, can we rule out all full pocket shims as contributors to a ski jump? (i.e. both flat and tapered). If not, why not?
Attachments
Good idea to clarify the terms here. I'm using "ski-jump" to describe an unwanted relief in the fingerboard (forward bow) only. That is a dip in the board somewhere that can't be corrected with truss rod adjustments.
This only concerns the neck; it has nothing to do with its relation to the body and strings, etc.
That's probably what I was thinking when other guys were saying "ski-jump"....
LS
Turnaround
Commercial User
So can we rule out your use of the term as it relates to the use of shims? Do you see any way that a shim could cause a bow in the neck beyond the place where the shim is installed - i.e. the neck pocket area? If so, please explain how this might occur.
Yes to your first q, and no to the second. I was thinking of something else when I was using the term "ski-jump". To others, this obviously connoted something having to do with the neck's relation to the body, so it sounds like I was laboring under a different definition of the term.
"ski-jump" as it pertains to the angle of the neck, etc., does have some interest tho....
LS
There ya go! I've had a couple of bolt-on-basses where the heel, when viewed laterally, appears to be "lifted" whether by means of an uneven pocket and/or pre-existing shim. However, when scoped-out with a straight edge, the neck topography is WNL (appropriate relief, straight where it's supposed to be straight, no ski jump). It's almost an optical illusion...which is why I eyeball my work but always verify via instrumention (straight edge, pocket rule, fret rocker, feeler gauges, etc.). Good call, unclejane!
Riis
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