Can you shim the neck too much?

magic2119 · #1 03-29-2010, 01:11 PM

howdy folks, i sent my bass to the local guitar shop to have him drop the action.

basically. the saddles are all the way grounded out, and he put a small piece of sandpaper in the neck pocket to shim it. he said he didn't want to go any higher with the shim or you start to get problems.

what i want to do is shim more, and raise up the saddles a bit so they aren't all the way on the bridge plate. if i do put a larger shim on the neck, will it create problems?? please advise

also.. all he used was a piece of sandpaper about 1" long and 1/4" wide.. i assume this isnt a very good thing to use for the shim, so i'm planning on using a bit of thin cardboard cut out using the neck as a guide so it fits well in the pocket. is this the best way to make shims?

thanks a ton!

CapnSev · #2 03-29-2010, 01:14 PM

My bass had similar problems with the saddles. I used a section of 2 playing cards for a neck shim, and problem solved. It really shouldn't take that much to be able to fix things.

I personally think a little shim doesn't really make a difference in the tone or quality of the bass. A lot of companies actually have shims installed from the factory.

Greevus · #3 03-29-2010, 01:17 PM

YES! Shimming is really an art. I've shimmed a few necks very slightly and made all the difference. I've REMOVED more shims than adding, and they've all been too large.

dmusic148 · #4 03-29-2010, 01:25 PM

It's not rocket science. If you need a thicker shim, by all means add one.

magic2119 · #5 03-29-2010, 01:50 PM

i ended up adding a cut out playing card at the bass of the neck (the guy that did the setup on it put the piece of sandpaper it in the middle of the pocket, not the end) and played with the saddles a bit and got it adjusted just perfect. thanks for the quick responses. and i will never be paying for a setup again, as the one he did wasnt great

Pilgrim · #6 03-29-2010, 02:37 PM

Setup involves a balance between shimming and bridge adjustment. If you want a bit more range of adjustment on the bridge, no harm in adding another thickness of sandpaper or biz card under the neck...you can do a lot more shim than that without hurting anything.

Yes, it's possible to shim too much - but this isn't it.

lethargytartare · #7 03-29-2010, 04:32 PM

And just to give you a direct confirmation -- sandpaper is fine -- I find it doesn't compress much. I avoid anything coarser than 100. If I were after a perfect shim, it'd be a an angular/sloped piece of wood that fits the pocket perfectly...but I've never had the patience to make something like that hahaha

BassBerg · #8 03-29-2010, 04:47 PM

I have yet to shim a neck too much. Anything from two playing cards to a credit card thickness will not harm a thing and usually do the trick. Good Luck

Tusec · #9 03-29-2010, 04:59 PM

Quote:

Originally Posted by magic2119

the guy that did the setup on it put the piece of sandpaper it in the middle of the pocket, not the end

Sounds like he should be in another line of work.

walterw · #10 03-29-2010, 08:21 PM

the trick to taller shims (if you're not dan erlewine and aren't set up to make a perfect 2-degree wooden wedge) is to use a couple shims of different thicknesses to support the neck along the length of the pocket.

the thicker one (in this case, saddles against the plate) goes in the bridge end of the neck pocket. the second, thinner shim goes in the middle somewhere, so it can support the neck and keep the screw pull from forcing it into a kink over time.

i lay a small straightedge on the end shim and the edge of the pocket, and slide the middle shim back until it touches the straightedge. a drop of superglue to hold it in place and i'm good to go.

magic2119 · #11 03-29-2010, 10:03 PM

thanks a ton everyone for all the responses. yet again TB blows my mind with the kindness and punctuality of everyone's responses.

Mike M. · #12 03-30-2010, 01:34 AM

I just shimmed the neck on my bass yesterday by using some shim stock from work. Started off with .025 which was too much, wound up with .015 and it now feels and plays great.

Had the same problem as you. A few of the saddles were all the way down to the bridge plate and the strings were still too high for my liking. Felt like I was fighting my bass to play it. Not now! I'll tell you what though...that high action really built up my finger strength!

mongo2 · #13 03-30-2010, 03:35 AM

I've run into a few situations where I use thicker shims to compensate for a neck pocket that's too deep or a neck heel that's too shallow (or both). I've used a 1/8" flat full pocket shim a couple of cases.

JustDavid · #14 03-31-2010, 06:02 PM

We seem to have a few shimming methods in the discussion here:

1/ shim between the bridge-ward pair of screws & the bridge side of the neck's pocket.
2/ thicker shim in 1's location & a thinner shim between the bridge-ward pair & the nut-ward pair of screws.
3/ a wooden ramp
4/ a shim in between the bridge-ward & nut-ward
5/ a shim located like 2's but the same thickness.

I'm no great shakes at this & I've only ever done #1. I'm not seeing a lot of point in #2 compared to #1; seems to me like the pocket edge would make a better resting place for that extreme (I'm NOT going to disagree with WalterW; just saying I don't see why). #3 seems best but very very difficult to do. I'm not seeing benefits in 4 or 5; seems like raising the neck on stilts.

I've used business cards; highly compressed paper easily available in thin sizes. Wouldn't sandpaper tend to compress with time & need retightening either from the sand points going into the wood or from the sand being crushed?

walterw · #15 03-31-2010, 11:31 PM

Quote:

Originally Posted by JustDavid

2/ thicker shim in 1's location & a thinner shim between the bridge-ward pair & the nut-ward pair of screws.
I'm not seeing a lot of point in #2 compared to #1; seems to me like the pocket edge would make a better resting place for that extreme

what can happen with just a shim at one end or the other is that the middle zone is left with an unsupported gap, and the clamping force of the screws can pull that gap closed over time, bending the neck at the last few frets.

the idea is that the neck rests on the "real" shim that's changing the angle at one end, the pocket edge at the other end, and the thinner support shim (or shims) in the middle.

kai_ski · #16 03-31-2010, 11:54 PM

Quote:

Originally Posted by magic2119

i ended up adding a cut out playing card at the bass of the neck (the guy that did the setup on it put the piece of sandpaper it in the middle of the pocket, not the end) and played with the saddles a bit and got it adjusted just perfect. thanks for the quick responses. and i will never be paying for a setup again, as the one he did wasnt great

From your description of this particular Luthier, I wouldn't pay for him to do a setup again either. If I'm paying cold hard cash for a professional to shim my guitar neck, he better not be using a piece of sandpaper. I expect a precision cut piece of material that will fit snugly in the neck pocket and maintain/improve the fit and finish that the instrument ought to have.

Once you experience a proper setup from a legitimate Luthier, I think your opinion will change. Ask around among other bassists of varying genres (i.e. not just the Metal Heads, or Blues players) in your area or use yelp to find the best Luthier, not just the guy who sits in the back of the local guitar shop or GC. His shop should be neat, clean, and not cluttered with stacks of guitar cases (which might imply you'll be waiting for a long time to get yours back.)

walterw · #17 04-01-2010, 12:00 AM

+1 on having a reasonably neat shop, but those "stacks of guitar cases" could indicate a huge word-of-mouth based demand. (and FWIW, sandpaper is an excellent shim material, as it doesn't compress or allow the parts to slide around.)

JustDavid · #18 04-01-2010, 08:23 PM

Quote:

Originally Posted by walterw

what can happen with just a shim at one end or the other is that the middle zone is left with an unsupported gap, and the clamping force of the screws can pull that gap closed over time, bending the neck at the last few frets.

the idea is that the neck rests on the "real" shim that's changing the angle at one end, the pocket edge at the other end, and the thinner support shim (or shims) in the middle.

OK, so 3 points of contact instead of 2. That makes sense to me now. Thanks Walter, for the word on sandpaper also.

Tim Skaggs · #19 04-02-2010, 06:09 AM

+1 on the sandpaper as shimming material. Finer grit is better; 220-400 works well. Contrary to the name, most sandpaper doesn't use "sand" as the abrasive material. I would think that playing cards would be too slick & might allow the neck to shift if the pocket wasn't as tight as it shoud be (like on an early 70's Tele bass). It depends on how smooth the bottom of the pocket and the back of the neck heel is. If the bass reqired a really thick shim to get it "in playing range" I would be looking at other things like; non-original neck or bridge or other structural mismatch of some kind. Also, as was pointed out, thick shim = a void or gap and some high stress on the very end of the neck that can result in a high spot at the last couple frets over time.

electracoyote · #20 04-02-2010, 06:23 AM

Try everything you are reading in this thread, because, unless you glue it in or do something permanent, everything you do can be reversed. I've used sand paper, coins, picks, credit cards, and one of my students is an excellent woodworker and makes me perfectly ramped shims from hard maple.

I believe you CAN get a shim too high and put the neck at a severe angle, but I can't imagine a neck requiring that. Ramping is a good idea, and I have achieved this with masking tape (many layers at the base of the pocket tapering off to only a couple of layers at the top of the pocket).

Still, I hate shimming a neck, and only do it as a last resort and only enough to give me some play if the saddles are bottoming out.