How To Shim A Neck

[Jean-Luc Pickguard]

[quote name='RhysP' post='496655' date='May 24 2009, 04:07 PM']What if you've got a through neck bass?
[/quote]
yer f'ked
- that's why I like my epi thunderbird.

Great post Bod - when I did all my bolt-ons to get them just how I like them I never thought of using a capo to stop the strings unwinding.
My Bitzer fretless Precision has a slice of the missus's credit card in the neck pocket. She wasn't happy at the time, but it stopped her buying shoes.

[silverfoxnik]

[quote name='stinson' post='496319' date='May 23 2009, 09:13 PM']That Sir, was superb. Well done. That JV brings a tear to my eye, reminds me of one I let go years ago [/quote]
+1

on both counts....

[Kongo]

I did this on my old Yamaha RBX375 cause the bridge plate was like a 1/4 thick plus TALL SADDLES!
I used a business card from my work exaclty as you did.

Also may I add, a shim can be applied to change the action allong the neck.
You can shim the other way to make the strings closer at the nut too.
But at the possition you did you could also do this if you find the action past the 12 fret is a bit too high compared to the nut...in other words, it can even the action out.

Great guide though...I hear so many ask about how to shim a neck on many forums, often cause they fitted a BadAss bridge (do these really raide the action that bad? mines fine).
Now they may read here.

[Dread Bass]

Well ive got my project for the day now ive been meaning to do his on my jazz coppy since i changed the bridge for a badass.

[Dread Bass]

Done it already it worked a treat and was quick. Only one problem i cant find the Allen key for my badass bridge .

Anyone got a spare? vOr can someone tell me the ssize as i cant find it on the net.

Edit allen key size is in the stickied post on badass bridges.

Edited May 26, 2009 by metaltime

[leonshelley01]

I had to do this a while ago after replacing the bridge on my Jazz with a Gotoh 201 and was easy enough to do. I'm pretty sure that my 10 year old son could follow the instructions in this thread and do a good job too! Well worth a sticky!

[Paul_C]

As an alternative to the business card, you might want to try a piece of wet and dry paper the length of the pocket - folded a third of the way along and cut to shape - that way you get something that grips both neck and body.

[Dr.Dave]

Thankyou for taking the trouble - I'd like to add my voice to those who regard your excellent affort as sticky worthy.

I shimmed my Precision exactly like this 20 years ago and never a hitch/problem - except I used a specialist material for the shim available from Embassyregalfagpacket dot com!

[Huge Hands]

BOD2 - this is a genuine question, not trying to trip you up or anything as I don't know the answer.

I will need to do this for the first time soon and something in your thread has been niggling at my murky brain.

If the neck needs to be raised to lower the action, would it not be better to shim the whole length of the neck pocket? Surely just shimming one end would cause a tilt in the neck, effectively lowering the action at one end and raising at the other?

I have just refitted the neck to my stripped Squier and noted it will probably need a shim. The action is really high, but it looks uniformly high - i.e. the neck just needs lifting, rather than tilting?

Does my question make sense? I'm happy to be scoffed at if I'm missing something and have just asked a total "noob" question!

[BOD2]

Good question Huge Hands.

I've thought hard about this and, to be honest, I can't see much difference in the result you would get from either technique (i.e. shimming the whole pocket or shimming just the back of the pocket).

Given that the problem, in this example, had been cause by fitting a BadAss II which is slightly higher than the original bridge, then it makes sense that raising the neck by the same amount would also fix the problem.

However, if you ANGLE the neck with a partial shim I think you need less thickness in the shim that you would with a full length shim to achieve the same result - because the angling has an effect as will as the shim thickness. Less shim thickness in the neck pocket is probably a good thing.

Also, cosmetically, you cannot see a shim at the back of the neck pocket - it's completely hidden by the neck join. A full length shim would be visible and would not be very attractive.

So these are the only two reasons I can see - less shim thickness and you cannot see the shim. However, I'm no luthier so there may be some other reason that I am missing, but full length shims are uncommon.

[Huge Hands]

[quote name='BOD2' post='498538' date='May 27 2009, 10:06 AM']Good question Huge Hands.[/quote]

Ha ha, thanks - a star for me!

I had another think about this on the way to work - I figure that as the nut is fixed, then angling the neck is in effect doing the same thing? I guess to drop the action across the board you'd have to grind out the nut?

Anyway, it's a bit confusing, but I think I may have my head around it. Great thread, thanks for the extra tips before I attempt this myself.

A Mini-Hands is due any day soon though, so this may be put on the back burner for a while!

[BOD2]

[quote name='Huge Hands' post='498554' date='May 27 2009, 10:31 AM']I had another think about this on the way to work - I figure that as the nut is fixed, then angling the neck is in effect doing the same thing? I guess to drop the action across the board you'd have to grind out the nut?[/quote]

Maybe, but think of it this way....

If you were to put a 1 inch thick block under the bridge and a 1 inch thick full size "shim" in the neck pocket so that both bridge and neck were raised by exactly the same amount.... would the action change at all ? I don't think it would (it would make cleaning the body under the strings easier, though)

I think it's more of a cosmetic thing - no one wants to "see" shims in the neck pocket so using a partial shim keeps it all hidden.

(Good luck with Mini-Hands !)

[Huge Hands]

Hmmm.... Plenty to think about there.....

I'll let you know if I ever get round to doing it!

[BigRedX]

Last time this question came up I did a couple of diagrams showing how various neck adjustments affected the action:





IMO this topic should really be added to the Wiki rather than stickying it.

[Kongo]

Shimming the end of the neck pocket also makes the actiob even throughout so even if you like your current action but would like it the same all along the fretboard you can shim for that too.

[BigRedX]

Sorry, but that's completely wrong. The only difference between shimming at one end of the neck pocket and shimming the whole neck pocket is the thickness of material needed to get the same change in action and the position of the headstock in relation to the body. It's all simple geometry - look at the diagrams I posted.

[Kongo]

[quote name='BigRedX' post='503131' date='Jun 1 2009, 06:09 PM']Sorry, but that's completely wrong. The only difference between shimming at one end of the neck pocket and shimming the whole neck pocket is the thickness of material needed to get the same change in action and the position of the headstock in relation to the body. It's all simple geometry - look at the diagrams I posted.[/quote]

Well it happened to my Yammie.
I was told it would, tried it...it did!
Action is the same throughout pretty much.

[dave_bass5]

[quote name='stinson' post='496319' date='May 23 2009, 09:13 PM']That Sir, was superb. Well done. That JV brings a tear to my eye, reminds me of one I let go years ago [/quote]

Yes, a very big thanks as im planing on doing that tonight on my P5.

A question. While my action is ok and ive not bottomed out yet would this help to keep the height of the strings a bit more constant from neck to bridge?

And that also looks very similar to my old JV. Mine had all gold hardware on it though.
Sold it to the Bass centre for £300. Idiot.

EDIT: Just seen kongos post about the action being evened out. exactly what im after.

Edited July 15, 2009 by dave_bass5

[Badass]

Thanks for the very useful info contained here.

I now have a cheapy fretless that sounds like a million $$$

[dave_bass5]

I just wanted to report in and say all went well. While i could have done it without this guide, it certainly gave me more confidence so another big thanks to BOD2.
It certainly has made a difference. The action seems a lot more even down the neck now. I still have a bit of choking around the 14 fret and above if i play too hard but i dont see that as a real problem. I shouldn't be up that high anyway, im a bass player :ph34r:

I also wrote my name and postcode on the card before i put it all back together. A little more insurance in case i loose the bass and then it turns up.

[7string]

I've just read this thread and here's another method for you.

I have a video tutorial by Dan Erlewine which stresses the need for a full body shim rather than just a Fender-style one at one end of the neck pocket. Dan is the man when it comes to guitar repair and works for Stewart-Macdonald guitar shop supply.

The reason given for this is that the Fender one leaves an air space which can take in moisture eventually causing a "kick-up" or "rising tongue". This is where neck swells and the last few frets are angled uphill rather than downhill or flat, so strings constantly buzz against the upper frets. The bass would then need a partial re-fret and maybe some wood taken off the fingerboard.

Ideally a shim should taper from the height needed at the butt end of the neck pocket to zero at the top. This prevents the air-space problem and the possible consequences. If you have some woodwork tools and skills you could trace the neck pocket, lay out the holes for the neck screws, then grab a block a wood cut it the same size as the neck pocket and drill the holes for the neck screws. Bandsaw from your measurement to zero, clean it up and you're good to go.

However, I don't have either the machinery or the skills

The alternative is to lay out a ladder of 3 or 4 narrow strips gradually getting thinner towards the top of the neck pocket. Put a ruler over the top to check that it goes from your measurement to zero. I've used cardboard in different thickness (box to business card to cornflakes pack) to get this.

I know this goes against what has already been taught here, but it's essentially the same thing with 2 or 3 gradually thinning shims added. I've done to a couple of instruments and it's only a little more work than the Fender shim.

I'd rather spend a little more time trying to find a couple of thinner materials than have a potentially expensive repair further down the line.

Edited September 13, 2009 by 7string

[flatwound]

May I add my 2 bobs worth...? well done BOD2, and the diagrams from BigRedX, a work of art, (what program was used there ?).
I did this recently to a "no name cheapy" bass that I have and intend to defret,... if it turns out to be feasible, and / or worth the effort..??

Can I add these tips... as an alternative to cardboard, which could possibly compress over time, I suggest old X-Ray negatives ([i]us old blokes should have plenty[/i]) which vary in thickness, as shim material,....and for self tapping screws, a method I have learned over the years is to replace the screw, put "[i]sligh[/i]t" downward pressure on it and turn it in the opposite direction, 99% of the time it will drop into its original thread, and you will feel it. This is good to do on wood and plastic, and will save the screw cutting another thread, and stuffing the original, and therefore, making the "toothpick / woodglue" repair unnecessary.

[TimR]

Its counter intuative, but adding the shim does not significantly raise the heel of the neck up. In effect it lowers the neck at the nut.

I'm using simple figures for illustration. Pocket 100mm. Neck 1000mm, card 1mm. The neck pivots at the top of the heel, where the neck meets the body. The card raises the body end 1mm, but (using similar traingles and the demonstartion figures, imagine a lopsided see saw) this will lower the nut by 10mm and hence significantly change the angle of the string from the nut to the saddles. That is why you can then lower the saddles. In reality the card is much thinner so the nut is not lowered so much, probably around 3mm.

With this in mind it is possible once you have settled on the right thickness of card that does the job, to actually plane a wedge OFF the back of the neck, equivilent to the wedge you would put in. Although the neck is no higher, the nut is much lower and has the same effect.

Edited September 16, 2009 by TimR

[OldGit]

Great description of how to do this.

I dab a little Pritt Stick glue on shims to hold them in pace during re-assembly and subsequent neck removal for truss rod fiddlin'.

[gabson]

Spot on! nice picture and great quality! hard enough doing the job sometimes whist taking photos at the same time????

My fave method is to glue a piece of veneer on with a couple of blobs of PVA to a larger block of wood. Grind down one edge of the veneer to create a very good tapered shim. The taper takes care of "air pockets" meaning more of that all important tone transfer!

Spot on
Jack