[help/suggestion] Fender bass neck shim

Discussion in 'Hardware, Setup & Repair [BG]' started by Reviz, Aug 27, 2017.


  1. Reviz

    Reviz

    May 2, 2010
    Italy
    I would like to put a shim in two of my basses, an American Standard P Bass and an American Standard J Bass.
    Cause I would like to do a nice job (I mean use a wooden shim), how can I measure the right angle needed?
    I saw that online is possible to buy shims with various degree, but I don't know which one to buy.
    I think I would prefer an angled shim, flat is going to be higher (I need about a 1.5 mm of height).
    Thanks to everyone will contribute!!
    Best

    ps: is a flat shim safer for the screw holes in the neck? (I mean in the long run)
     
    Last edited: Aug 28, 2017
  2. Picton

    Picton

    Aug 16, 2017
    Reading, MA
    1.5 is actually a MASSIVE amount of shim. I've shimmed many Fender necks and never needed more than two business cards.

    I respect your desire to do it "right," but especially if you're shimming the body end of the cavity, it's not even remotely something to fret over... or spend money on. Just start with a business card and some scissors and keep adding layers until the buzz goes away.
     
  3. Reviz

    Reviz

    May 2, 2010
    Italy
    I mean 1.5 of "flat height". With this additional height the strings will touch the frets with the saddles all the way down.
    With an angled shim it will be much lower.
     
    Last edited: Aug 27, 2017
  4. rwkeating

    rwkeating

    Oct 1, 2014
    Chicago
    none
    When I shimmed my bass neck, I used very thin aluminum plates (two, 0.025" thick) across the entire surface between the neck and body. I felt this was better than putting the neck at an angle, but doing it this way requires a thicker overall shimming (that's a strange word :) ) By going with aluminum I didn't have to worry about it being flat since it was and it was easy to work with.
     
  5. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician
    I can't argue about how you felt. But it wasn't better.
     
  6. 202dy

    202dy Supporting Member

    Sep 26, 2006
    Rule of thumb: Change at the bridge equals twice the thickness of the shim.

    If what you are saying is that the guitar needs another 1.5 mm of adjustment at the bridge then a shim measuring .075 mm (~.030") will do the job. That's roughly the thickness of a thick business card.
     
  7. Reviz

    Reviz

    May 2, 2010
    Italy
    What a useless post without an explanation. Why not?
     
  8. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician
    There's nothing "better" about full flat neck shim. It's different, not better. There are myths about how a partial shim can cause a ski-jump, but that's been debunked. And there are opinions (non-substantiated) that there is a difference in tone, and such claims also suggest that the difference in tone is a negative difference. So what do you think is "better" about it?
     
    David Jayne and Rallypoint_1 like this.
  9. rwkeating

    rwkeating

    Oct 1, 2014
    Chicago
    none
    @Turnaround, I know you didn't ask me, but I'd like to reply to continue the conversation as I value your input.

    My thoughts against a partial shim is that the clamping forces between the neck and body are no longer uniform. Does it matter? In my mind it did but I am open to further input.

    We go to great lengths when making a neck and neck pocket even for a bolt on. Then, when you put in a partial shim you have 3 areas with different clamping characteristics.

    1. Neck wood to body wood (on the spot toward the nut)
    2. neck wood to air (in the middle)
    3. Neck wood to shim, shim to body wood (on the spot towards the bridge.)

    Maybe #2 isn't neck wood to air, but if it is neck wood to body wood, then some bending has taken place. Even if that doesn't cause the ski slope (as you mentioned) is that really a good kind of neck joint to end up with?

    Thanks in advance.
     
    Mili and bunnykeeper like this.
  10. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician
    I think this is one of those instances where there is a theoretical answer that seems to make sense, and a practical one where the differences are immaterial. I have never been able to detect any sonic differences in a bass when a partial shim was used or a full pocket shim. Nor have I been able to measure a consistent difference using a spectral analyser. That's not to say it isn't there - I just haven't seen or heard it.

    I have a test setup in my shop that has been there for over a year now trying to detect any any distortion that might occur in the neck heel when bolted into a neck pocket with a shim. So far, if there is any distortion, it is not measurable with any of my tools which are accurate to a fraction of a thousandths of an inch. In other words, in practical terms, I have found no advantage to a full-pocket shim over a partial one. I think you will find that the other techs in the Pro Bench here on the forum are of the same opinion.
     
    David Jayne and rwkeating like this.
  11. Picton

    Picton

    Aug 16, 2017
    Reading, MA
    In theory, a perfectly flat/straight neck heel and a corresponding flat/straight neck pocket, mating perfectly, is indeed the best way to go.

    In reality... every guitar and bass neck pocket I've ever seen is NOT like that. They start out that way, but manufacturers add inspection labels, dried mucky poly or nitro overspray, the scattered sawdust left over from drilling the holes for the neck bolts, even the gunk from where they drill the holes they use to hang the bodies to dry.

    Ever seen a dead-flat, dead-straight neck/body join? I doubt it. Yet the instrument still sounds fine.

    Once you accept that kind of compromise, an extra business card seems minor. Especially since it works so well.
     
  12. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician
    Actually I have. Several, but not generally on production line instruments. It used to be that Rolls Royce produced engines for their cars that were so closely milled that there was no need for a gasket between the engine block and the cylinder head. Didn't make for a better running engine, but you have to admire that level of attention to detail and quality control.
     
  13. brianmharrison

    brianmharrison

    Oct 11, 2007
    Atlanta
  14. bolophonic

    bolophonic

    Dec 10, 2009
    Durham, NC
    People be overthinking the bolt-on neck.
     
    digmeout, Picton and mesaplayer83 like this.
  15. mesaplayer83

    mesaplayer83

    Jun 27, 2017
    What constitutes "doing it right" is a matter of opinion - for example, what is the functional difference between a partial shim and a micro-tilt device, as employed on numerous Fenders, G&Ls, USA Peaveys, etc...? Also, many would agree that EBMM makes some of the best production instruments out there - yet, when I removed the neck from my late model US made Sterling 5 HS, it had a partial shim that was clearly from the factory...
     
    Picton likes this.
  16. BaileyMan

    BaileyMan Supporting Member

    Jan 8, 2012
    San Francisco
    I'm no luthier, nor instrument tech, but I'm a pretty confident DIY guy and I do pretty much all my own work that doesn't require special tools. I shimmed a neck once with a layer or two of business card and it came out perfect. Played like a dream afterward...of course, YMMV...
     
    Picton likes this.
  17. brianmharrison

    brianmharrison

    Oct 11, 2007
    Atlanta
    Never said a business would not work, but since you asked...using a business card instead of an actual shim leaves a gap where the edge of the paper ends due to the difference in caliper because there is no way to add an angle to a business card. Not to mention paper disintegrates over time. The suggested shim from stew mac is a better long term solution thus me saying it was the right way. Your shim from the factory in the EB...was it a business card?
     
  18. mesaplayer83

    mesaplayer83

    Jun 27, 2017
    No, the EBMM factory shim was a piece of thin plastic with holes for 2 of the neck holes to pass thru, and was actually smaller than what most would use for a piece of business card... I'll note that you didn't comment on any functional difference between a partial shim like half a business card and a micro-tilt mechanism - why not?

    Stew Mac is in the business of selling things - sometimes needed, sometimes not - just sayin'... Personally, I'll defer to the knowledge of people like Leo Fender, EBMM, Peavey, etc... - their results speak for themselves...
     
  19. brianmharrison

    brianmharrison

    Oct 11, 2007
    Atlanta
    My intention is not to start an argument. There is no functional difference between a business card, microtilt or a shim meaning they all accomplish the same goal. However, I am assuming the OPs bass does not have micro tilt (which is obviously the easiest solution, but he would not be asking about a shim if he did have that feature). What is the next best alternative then? A business card will work as I said, but it is not the best long term solution for the reasons I have already mentioned. A wooden shim (or plastic) that has a slope to it is a better long term fix. Factory shims are not paper because they are not a good long term solution.
     
    Last edited: Aug 29, 2017
  20. mesaplayer83

    mesaplayer83

    Jun 27, 2017
    I'm not looking for an argument, either - but what you're referring to as a "better fix" is merely your opinion, and is not supported in actual practice... The reason why I bring up micro-tilt mechanisms is because they also leave somewhat of an "air gap", that you cite as a reason for not using partial shims - yet, they have been employed by some pretty knowledgeable people... Also, the plastic shim EBMM used didn't have any slope to it - it was less than 1" long in the neck pocket... Lastly, card type partial shims have been used by manufacturers - in fact, I am unaware of a tapered shim ever being used by a manufacturer, to be honest... You are certainly entitled to your own *opinion*, but it really has no basis in fact...
     
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