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The answer to this question may be obvious, but I have never seen it addressed. When you re-set the neck angle on an acoustic guitar as you" back-set it" the end of the fretboard rises off of the top. I assume you need to " shim" the underside of the fretboard so the fall-away is proper. ??

that is what should be done IMO...my '86 Taylor K-20ce had some major issues with the top moving which necessitated the repeated removal of the neck for angle adjustment...after the second time this operation was done the effect on the planarity of the fingerboard was pronounced and I rather flamingly made a call to the head of their repairs department...they actually asked me what I thought should be done to correct the issue!!!!!...my reply was 'why don't you make a wedge of ebony and insert it between the fingerboard and the top'...sheeshus, you would have thought they could have figured that one out...also be aware that as you adjust the neck angle you will be affecting the scale length which will require the saddle to be moved back in compensation....if this reset of the neck routine ends up happening more than a couple of times you will most likely have to replace the bridge so that the back angle of the strings as they pass over the saddle doesn't become so steep as to cause string breakage (this is also something Taylor neglected to do with my guitar and I again had to tell them how to do it )

as of this writing it appears as if the instrument has finally settled into its lifetime shape and hopefully will never have to go back to the factory again...I certainly hope this is the case because as Taylor has become more and more mass production oriented I feel their abilities to do hands on work has diminished to the point of being worthless....

If the guitar is not of great value one could clamp and glue the fingerboard extension to the top and live with the small angle.The only other option is to make a wedged shim.
There are actually people out there who believe that a steel-string neck does not need to be removable....

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In Markham,Virginia

It's a case-by-case decision. A bit of fall away at the extension is a desirable feature for the vast majority of acoustic players. Too much can be unsightly, and could render the upper frets almost unusable in extreme cases. I just finished a '34 Martin that I did not shim, and most likely will not shim a Martin 12 string I have the neck off of right now. Overall, I'd say I shim the majority of fingerboards on neck resets, but certainly not all. It's a judgement call - you have to decide if a shim is desired with each individual instrument.

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Hi David & others,

Care to share your method of making a shim? (yeah I know, like making inlay filler dust, but some folks here will find it useful)

Oh, how I wish I had a method.

I will typically complete the neck set first (fitted, not glued). After that, I don't have any hard rules or procedures. Using feeler gauges or various wedges, shims you can fit under the end of the extension (with the neck clamped down) to find how much shim you want at the end, keeping in mind a bit of fall away is good. No formulas to figure how much is needed depending on how much you shaved off the heel or anything, you just have to check and measure.

Then I will sand a small wedge of the same material as the board, tapering to near nothing just before it reaches the joint. Check the fit of the shim, make sure it doesn't kick up the extension. Glue it on, fit the sides, occasionally touchup the shim, though often sanding to 240 and buffing will suffice. Then I will typically have to fit the bottom a bit more after gluing. Sometimes the shim has to be curved on the bottom to match a slight hump in the top (with a straight wedge you will often see a hump resulting in the board around the 15th-17th frets). Sometimes I do this with chisels, sanding blocks, or even sandpaper flossing at times.

As always, dry clamping and rechecking is key. There are tons of other variations on methods though. I have glued shims to the top before putting the neck on with the idea of being able to level the area with a long leveling block I made to reference off the bridge, but don't plan on doing that much anymore. It was an idea once, but really just took longer for me get the same results as the prior fitting method.

Bound boards are tricker to get a clean look. I've made spruce shims when they were small enough to blend in with the top. I'll occasionally do a bound spruce or ebony core for the shim, but it's so difficult to get a clean binding joint all the way around. I would love to hear some other opinions on this, as I've still not found an easy and reliable way to shim a bound extension invisibly. It can be done, but it's so dang labor intensive to get a clean line, and sometimes near impossible to match the ambered lacquer on white binding, or even the color of the binding itself. You can see quickly how a spruce shim can be more easily made obscure, blending with the top rather than blending binding in with the edge of the board. I'm more than open to other solutions here though.

So it's really a "whatever it takes" kind of philosophy for me. Generally glue on a shim, fit it to the top and to set the right angle, keep a bit of fall away, avoid the hump, sometimes touchup edges if necessary, sometimes before assemble (Martin), sometimes after (Gibson). Check everything well, get the angles right and make it look good. That's about all the advice I can think of at the moment.

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Eschew obfuscation, espouse elucidation.

I've never cut a wedge for this type of use before..typically I cut wedges for trim work using my miter saw but I think that would be rather unsafe in general for this type of application...

what comes to mind is using either a table saw or bandsaw with a jig to hold the block of wood in place as it is being cut...obviously one will need to take careful measurements for the dimensions of the wedge and probably make it oversized so that adjustment can be made...making a sled with clamps to hold the wood while being cut and running it through the machine is how I would approach this because as previously noted I would consider a miter saw cutting through a thick piece of hardwood to be risky for both the wood and the user...the big issue with a miter saw is getting the block positioned and held in place so that its not ripped out of your hands and there is also the issue of the kerf boards dropping away from the table of the saw which creates a very unstable situation (I've had many a piece of wood ripped out of my hands when performing this type of cut before and that's with 3/4" stock!...the trick is to let the wood go flying while you pull your hand away from the blade)...

Thank you all for the input on my question. I think how you address the end of the fretboard when doing a neck-set is critical. It has to be clean and right-on, "thanks David." If the fall-away is too fast the trained eye or even the untrained eye will pick up something looks off. I am currently doing a neck-set on a 60's 00-18 Martin. It will definitely need to be shimmed. When I do shim I also sand the piece, tapering down to nothing. I put a couple pieces of double-stick on the piece to control it on the belt sander. You have to check the "fit" over and over to get it perfect. Today is my first day on the site! This is good stuff! Thanks again.

lotsa ways to get it done. HANDWORK is tested here. In fitting of this type, any fine tuning you do is help with carbon paper, and/or chalk.

One tip for beginners ~ don't cut to size until after it fits. Leave it a little long for clamping. When sanding, it's too easy to round off edges, ends, and corners. Then you'll be doing it all over again Ask me how I know....

This is where crafsmanship comes in. Enjoy it. Even though one might make a jig for it... Ducking and running...

The belt sander sounds the safest. What about the bottom dome on radiused tops? I was going to make a negative to fit a fretboard to the 25' dome, Sand some quarter cedar to the dome, and then sand the fretboard with that piece, but going into the top a little bit may be easier on this one. Maybe a round scraper by hand. Not sure yet.

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Honestly, I pretty much never shim the fingerboard extension during a neck reset. I get the feeling I'm in the minority on this, although I notice Frank Ford doesn't shim either. My thinking is that a shim doesn't look particularly natural, as the fingerboard gets rapidly thicker near it's end. Of course a steep fall away doesn't look quite right either, but I like it a little better. As far as playability, few people spend much time playing up there. I've done hundreds of reset and never had a complaint. If I was resetting a guitar with a cutaway, I might rethink this. But I can't remember ever resetting the neck on a guitar with a cutaway. Additionally, if I'm also doing a refret I will plane some of the fall away out although it still ends up having considerably more fall away than a new guitar would.

When I've had to make fingerboard shims for other situations, I've simply double-stick taped the shim stock to a flat backer board and belt sanded it. That seems to work well.

While each situation is different, I am beginning to think taking the " middle of the road " approach may be the best way. In other words, if the fall-away is drastic, shim it just a little to make it pleasing to the eye, but not too much to make the end of the fretboard look chunky. Thanks again.

I make shims with my thickness sander using a backer board, scrap shims, and double sided tape.

I don't understand having to use a shim if the top has the proper radius.......My problem is having it too high and I have to sand down the top in the neck area to get the proper taper....Am I doing something wrong?....Larry

You’re not missing anything on a new build—they are referring to an older guitar getting a neck reset. The fretboard extension area was sanded to fit the original neck angle at the time it was originally built. With age the upper soundhole and extension area will have sunk a bit from string loading, so after the neck rest the fretboard extension will be toe'd up at the sound hole