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shims: what are the drawbacks?

Discussion in 'Hardware, Setup & Repair [BG]' started by ::::BASSIST::::, May 10, 2005.

  1. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    i just bought a moses graphite neck. i put some da chromes on and the action was intolerable. i have had to resort to putting a shim b/n the neck and the body because the saddles are as low as they can go.

    what are the disadvantages of using a shim?

    also, under these circumstances, if i brought my bass to a luthier for a pro setup could he/she get the action just as low or lower without the shim or would i just be wasting my money?

    thanks :)
  2. Bongolation


    Nov 9, 2001
    No Bogus Endorsements
    Largely imaginary.

    On the other hand, most necks that have been shimmed have been reassembled with too much torque on the neck plate screws, cross-threaded or otherwise messed up, but it's not the shim that's doing it.

    It is believed that shimming or using a Micro-Tilt device can affect - either improving or worsening - sound, and I believe from my own experience that this may be the case, but it's completely unpredictable and rarely noticeable.

    To fix this problem without a shim would involve taking down the mating surface on the neck, and with a graphite neck this may be too much of an undertaking. Go with a shim.
  3. Well, you don't have to take down the neck at all. In fact, in my way of thinking, it would make more sense economically and technically if you were to remill the floor of your neck pocket. I don't know what model of bass we're talking about here but if it's a brand that has a lot of overspray in the pocket, sometimes just routing that down to bare wood is all it takes to even things out. Most overspray falls on the outer portion of the neck pocket - not in the deep heel corner. This makes the front of your neck rise and that screws up your height adjustment. This is just something I've noticed on some lower priced instruments. Even if this isn't your problem, you can still rout (or have routed) a hairs thickness off of the surface to square it and that might do the trick. Now, if all that does is lower the neck even further - but level it nicely! - then you can add a full pocket spacer the same color as your neck. This could be made from your neck wood or phenolic or even aluminum or colored acrylic. All of these materials will transmit the vibrations quite well to the body. And if you use machine bolts, you can really crank down on them to make it mucho tight.
  4. Bongolation


    Nov 9, 2001
    No Bogus Endorsements
    More sense economically and technically than just using a shim?

  5. BassyBill

    BassyBill The smooth moderator... Gold Supporting Member

    Mar 12, 2005
    West Midlands UK
    I used a shim when fitting a graphite neck to a Warmoth body - doesn't seem to be a problem, can't see why there should be one. Remember a "compressible" material like cardboard will become almost totally rigid when squeezed by the sort of compression you'll get in a bolt-on neck joint. Perfect engineering solution in my book.
  6. Jeeze yes, it would make more sense than milling the bottom of your graphite neck Jeeze

    Disagree? :rolleyes:

    Edit: This sort of thing is why I don't show my face around here much anymore.
  7. Bongolation


    Nov 9, 2001
    No Bogus Endorsements
    They're both inferior options to shimming in terms of potential disasters attendent to the levels of incompetence encountered in about 95% of the shops out there.

    I don't know anyone I'd trust to freehand route a neck pocket on a finished instrument that mattered to me.

    I've recently seen a fine example of a "professional repair" of this identical problem by a "reputable" Nashville repair shop. Amazingly, they managed to badly F-up both the neck and the pocket!

    Always go with the most reversible, least radical option that gets the job done. Don't dig a deeper hole, no pun intended.
  8. This is so stupid I don't know where to begin :rolleyes:

    First, my response was only to the idea of actually milling the bottom of the neck. If you took the time to actually READ the first sentence of my post, you would have read the point of my treatise. You didn't and of course, you didn't get it. If someone were to consider either milling the neck OR milling the neck pocket, I gave them an option for the neck pocket.

    Secondly, you are the only one in this thread foolish enough to mention freehand routing of a neckpocket. Any 1st year woodshop amateur would understand the pitfalls of that operation. I don't freehand route pockets and this isn't done that way either. I do this operation all the time with bearing guided bits. And I can shave a frog's hair out of a neck pocket if I need to. I can also shave that same amount from the front or the back - if I need to. It's not too hard and it's not impossible. It IS in fact a common occurrence in my shop.

    For you to characterize all professional repairmen, technicians, builders, and luthiers by anecdotal evidence and your inexperience with the process, is unfair. Some of us take great pride in learning the right way and ALL the ways to do things. Some of us, in fact, invent NEW ways to do these things. I am one. And if you've seen the Bible on the head of a pin or vascular surgery under a microscope and you've got any brains at all, you soon realize that this ain't rocket science and neck pockets aren't insurmountable obstacles.

    Since I haven't given my opinion on shims yet, here it is: Go for 'em! I use them, like them, and can make one of the best shims going - a tapered shim that maintains near 100% contact with all of the mating surfaces of the neck and pocket. Sorry it took so long to get around to it.
  9. Bob Rogers

    Bob Rogers Left is Right

    Feb 26, 2005
    Blacksburg, Virginia
    Hambone- I'm afraid that after rereading the original post, it seems to me he is saying that he shimmed the neck in the traditional way with a matchbook cover, credit card, condom wrapper, or something.

    Your suggestion of going at the neck pocket (and especially the point about overspray) is undoubtably the "right" way to do things. But for some of us old school players for whom sustain isn't a big goal (sponge under the strings anyone?) it may not be the most efficient method.
  10. Bongolation


    Nov 9, 2001
    No Bogus Endorsements
    "Freehand" here means anything other than CNT or at least a purpose-built jig.

    Well, you're in a tiny, miniscule minority of the self-appointed "luthiers" and "Guitar techs" out there that I've seen in over forty years of playing and dealing gear. The very large majority of these people, even those working in commercial establishments, are merely young hobbyists learning by trial and error on their customers' instruments. Some others are conscientious but simply incompetent. A very small number, well under 5%, are actually intelligent, skilled, knowledgeable, mature and talented craftsmen.

    Unfortunately, what happens to most of these guys is that they find themselves in more demand than they can handle, and their quality of work slides under the stress, and winds up being increasingly delegated to poorly supervised trainees or subcontractors from the first group I mentioned.

    OK, so which of the pimply-faced stoners at their guitar benches are going to trust to do your triple-bypass? :D ["Uh, shouldn't you sterilize that or something?" "Dude, just chill! I saw this on cable and there's nothin' to it!"]

    So...we BOTH say go for the shim? Great! Phew! Why was that so hard?
  11. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    for your info i am using a geddy jazz with moses graphite neck ( as it says in my signature).

    i there a preferable material to use a shim? right now i have a piece of cardboard from a veggie dog wrapper.

    i placed the shim as close to the neck pu as possible. good idea? a guy told me that this way i will get lower action near the 12th fret and more room near the nut.

    regarding neck tightness, one of the brass inserts in the moses neck has come completely loose so that when i screw the neck on into that insert there is no bite. should i use crazy glue to secure that insert or is there a better way? i tried just screwing the insert back in but it just came loose again.
  12. Again Bob, our friend Bongo brought up the idea of comparing shaving the neck to shaving the bottom of the pocket. I didn't! It was irresponsible of him to even mention it if it wasn't to be a part of the discussion. Of those two choices - without considering shims - shaving the pocket is the way to go. Who is to say that the pocket wasn't cut poorly in the first place? Knowing the way these things are made that's more likely than the neck heel being out of parallel to the face. I agree that shimming is certainly the first route to take - I would and most techs and repairmen would . But for Bongo to jump on me for broadening a subject HE introduced is ludicrous.

    You see, I believe that ANYTHING (almost) is possible with these instruments. I also believe that there a lots of small details that haven't been looked at before - that's how I discovered the overspray condition. By taking that approach and analyzing the true cause of poor setups, I can usually have basses play 10x better without stopgap measures. I don't go willy-nilly into things. But if all the evidence points to a poorly cut neck pocket, what is one who strives for top professional standards supposed to do? Shove a paper shim in there and tell the client that it's all fixed and shove him out the door? Nope, I won't do that and I wouldn't expect you to accept that either. What I would expect is a complete explanation and perhaps a visual of the problem so I could make the decision as to whether the correction should be made. If the client says go then I go. If I don't say go, then I don't go. When would't I say go? - likely scenario's would be vintage instruments or custom boutique instruments that should go back to the builder. But all actions would be seriously considered pro and con with plenty of study put into the operation. It's unfortunate that in 40 years Bongo hasn't been able to find concientious techs. Too bad - he's been asking the wrong questions of the wrong people. But I choose to do things my way and I am seeing good results from my approach.

    Take it or leave it Bongo but since I can fix the problem in more ways than one and I can do it well, you might consider that perhaps I'm on to something. ;)
  13. Yow, that hurts!

    I think I would use epoxy instead of superglue. Epoxy has more body and is actually closer to the original resin used to make the neck. The trick is going to be getting the insert back in there aligned so that it will take the bolt at the correct angle. I would slather enough epoxy on the threads of the insert to fill the void in the hole and then put a piece of tape across the face of the insert. You might also want to put a small piece of tape on the back end of the insert to keep the epoxy out to of the threads. Punch a hole in the tape so the bolt can go into the insert and install the neck in the bass with the other three (or 5?) bolts. For the last one, carefully thread your bolt into the insert so that it aligns with the hole in the body and then set it up to cure for 24 hours. Don't tighten the last bolt, just thread it enough to make sure it's got the insert lined up in the hole.
  14. bizzaro


    Aug 21, 2000
    Couldn't help but wonder. Isn't routing or taking material away from the neck pocket or neck acutally raising the action of the strings, and adding a shim lowering the action? Opposing goals and results. The string is the fixed point of height determined by the saddle and nut. Raise the neck(shim) and you will lower the action, lower the neck(route pocket) and you will raise the action? I just put a different bridge on a bass and have the saddles as low as they will go. Short of routing out where the bridge mounts,(I don't want to alter the bass permanently), it would seem shims would be the fix. But a deeper pocket would make it worse??? Am I missing something. And wouldn't some hardwood veneer be a great shim?

    On further research I see most people use a shim to "tip" the neck. I want to keep the neck pocket flat,the neck parallel to the body, and lower my action so I can raise my saddles. It would seem the proper correction for this would be an even full pocket shim. Off to the hardware store!

  15. Good question - it shows that you're drawing the relationships of the parts out in your head and trying to link them up.

    Yes, if the neck pocket started flat, further milling would lower the neck into the body and raise the strings. My suggestion was only to mill off the portion that was out of parallel with the face of the body. If your strings were too high, that would be the front of the pocket and it would have the same effect as shimming the back of the pocket. Besides, if one were to use a full pocket shim, it might be a good idea to mill the pocket perfectly flat to begin with. Then the all of the angle introduced to the neck could be in the shim.

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