Martin Neck Reset - Easy

About a month ago, I had a spate of neck resets that fought and fought. They just didn't want to cooperate. I'll write something about one of these in a little while but, for the sake of my sanity, I'd like to remind myself that, sometimes, they go well.

If you want a recap on why we reset necks and what's involved, check out my neck reset primer

Getting the neck off

If you’ve a bolt-on neck, life is considerably less messy. If you’ve a dovetail, glued-in neck, well, then we need to break out the steamer. But first, the fingerboard extension.

I apply heat to the fingerboard (carefully, obviously). In this case I’m using a heating blanket. I used to use a shaped metal block that was heated separately and then popped in place but the blanket makes things much more easy. Some poking around with spatulas helps loosen the glue. Often, it'll take a few heating/poking sessions to get things freed up.

Heating fingerboard extension to loosen glue

Loosening fingerboard extension for neck reset

Then the fun begins. Steam.

I remove a fret and drill a little hole, through the slot, into the dovetail cavity. There’s usually a small gap at the back. Once I have access in here, I fire up the steamer and begin to inject steam, through a nozzle, into the cavity. As I do, the hot steam will gradually soften the dovetail glue.

How much steam and how often it's applied varies from guitar to guitar but it's best to use as little as possible. There's quite a bit of wiggling and wrestling with a guitar as I try to get the glue to give up its grip. That wooden contraption around the guitar helps a lot. It provides some 'upward' pressure to help encourage the neck to move out of the dovetail as I wrestle with it. You get a feel for it—when to go with more steam, when to wiggle and, after a while…

It pops out. Brilliant.

Steam to remove guitar neck during reset

Dovetail neck joint disassembled

Setting the neck

Exaggerated illustration of neck reset

The neck angle is altered by taking a 'wedge' of wood off the heel. The image shows an exaggerated view of this—the green section is removed so that when the neck is reattached, it tilts back. 

It's really important not to take wood off the pointy bit of that wedge as doing so would move the neck closer to the bridge and actually alter the scale-length, throwing your intonation all out of whack. 


Chisels and sanding 'sticks' get most of the wood off.  When I've taken off enough to get me close to where I want to be, I finish off by moving to strips of sandpaper. Using then as shown lets me take off the last, smaller, amount of wood but also lets me get a good fit between neck and body. Taking more off one side or the other, during this stage, also allows me to adjust the side-to-side fit so the neck sits properly on the centre-line.

As I proceed, I'm constantly checking the set-angle (by sighting along the board), the centre-line set (by using a long straight-edge along the neck), and the fit between neck-heel and guitar-sides. 


Fitting neck-heel during reset

Checking neck set-angle

Checking neck alignment during reset

Putting it all back together

When everything's right, it's time to reassemble. Generally, the dovetail joint needs to be shimmed as our angle-changes will have altered the way the joint sits together. A couple of test-fits get me where I want to be and then it's time to heat up the glue-pot. In usual Martin-style, the glue goes only on the dovetail joint and under the fingerboard. The heel and body do not get glued on a Martin. This is one of the reasons Martin resets tend to be a little easier.

A properly fitting dovetail pulls itself together. A clamp for the joint and one for the fingerboard is all I need.

Reassembling acoustic guitar after neck reset

Dovetail neck joint re-glued

I like to leave things overnight for the glue to cure—probably overkill but it makes me feel safer. Clamps off and I make a little rosewood plug to fill the hole I drilled earlier. Once that's glued in, I can re-cut the fret-slot through the plug and reinstall the original fret. 

Plugging the 'steam hole'

Plug with slot cut. Will be hidden under the reinstalled fret

Some neck-sets require a full refret afterwards but we're good on this one. Only minimal fret-work is is needed. Also, Martins don't usually need any finish touch-up so this guitar's playing again—with a new saddle and a comfortable action—in no time at all. 

Textbook. Nice.

The Reset Button

Neck Reset Acoustic Guitar

The string tension on your acoustic guitar depends on a few factors. String gauge, scale-length and tuning all play a part but if you assume somewhere around 200 pounds of pressure, you'll be in the ball-park. 

If you sat there with 200lbs on your shoulders for years, odds are you might begin to buckle a bit. Your acoustic guitar holds up better than you would but that tension can take its toll. 

If you have any steel-string acoustic guitar for long enough, chances are good it'll need a neck reset at some point in its life. That string tension alters the geometry of the instrument and the most obvious way is that the action creeps up to a point were it's uncomfortable or awkward to play. When a reset will be needed is anyone's guess. Different guitars are, well, different. Could be five years, could be fifty. 

Most guitars have some additional height in the saddle to allow it be lowered, taking the action down with it. This buys some time but, eventually, the same thing can happen. It's not unusual, on older guitars, to see a saddle that's been lowered repeatedly and is little more than a sliver, barely above the bridge. 

Might be a good time for a reset, then. 

A reasonable rule of thumb is that, the plane of the frets should be at the same height as the top of the bridge (that's the wooden bit and not the white saddle). Putting a longish straight-edge on the frets can show you what the story is, as in the photo above. As you can see, it contacts a few millimetres below the bridge-top. Sighting down the frets from the headstock can give you a good idea visually if you don't have a long enough ruler. 

What happens in a neck reset?

Basically, we're trying to re-adjust the geometry of the guitar and neck so that straight-edge in the photo gets raised enough to touch or clear the bridge. That means changing the angle at which the neck joins the body.

To do this, the neck has to be removed and some wood taken off part of the heel. 


A neck reset on a bolt-on acoustic

Ahh, a bolt-on neck…

Dubious arguments about tone aside, if your acoustic guitar has a bolt-on neck, it does make a neck reset a little easier. The first step, you see, is getting that neck off and the easier that is for me, the cheaper it is for you. Bolt-on necks mean less hassle trying to get glue-joints to release.  

Bolt-on neck reset
Acoustic guitar neck set

The first image clearly shows the bolts in the neck block (we're looking inside the acoustic guitar here). Straightforward. Excellent.

The second image is the inside of the 'top'. The image is taken with a mirror lying inside the guitar. It's always a good idea to get an idea what's going on in here before starting major surgery, especially as bolt-on necked guitars from different manufacturers vary in how the handle things in this area. That block of wood glued to the extension and shoulder-brace, for instance, is worth some consideration. 

Guitar Neck Reset
Acoustic Neck Set

A little work to get that block to disengage and some work on the fingerboard extension is all that's needed here. You can see the way neck and body fit together relatively clearly above. 

Something I wasn't expecting was to encounter an epoxy-like material in the body mortice around the neck tenon. It was in the area around that white tape (marked with an X in the photo on the left). Because it wouldn't adhere well to this tape, I'm guessing its job was simply to act as a sort of gap-filler to ensure help ensure a solid connection here. Whatever, I noted it for reassembly and cleaned up the residue. 

Incidentally, I noticed a hairline crack in the heel between the two sockets for the bolts. It was pretty small and probably unlikely to cause problems but I made it good before proceeding to work the wood in this area.

adjusting neck set angle
Accoustic Neck reset

The reset itself is done by removing a 'wedge' shape of wood from the heel—more at the bottom, graduating to none at the top where it meets the fingerboard. Calculating the amount to remove can be done by a relatively simple formula but I tend to do that only to get in the ball-park and then finish by eye. 

The tape in the left photo gives me a line indicating the wood to be removed. There are a few ways to go about this but I like to bevel down to this line and then bring the sides to meet it. 

Guitar-Fix Neck Angle
Guitar-Repair Neck Angle

Like this. Wood is carefully removed from the sides of the heel now. Very carefully. It would be very easy to mess this up. I don't want to remove any wood from that far end where the heel intersects the fingerboard. Doing that would actually move the neck closer to the bridge and muck up the intonation. What we want to do is to take out that wedge shape I mentioned earlier. When that's gone, the neck joins the body at a slightly increased angle and this means better action.

Most of the work is done as shown in the left photo. When the bulk is gone, I'll test fit to the body and I'll remove the remainder of wood using sandpaper between body and neck as in the right image. This helps perfectly shape the heel-fit to the body. 

Acoustic instrument neck set
Repair neck angle acoustic guitar

It's important to check alignment often. As well as the set angle, I'm checking for side-to-side alignment to make sure I don't take too much off one side of the heel. That would point the neck too much to one side or the other—not good. 

Once I'm happy with the fit and alignment, it's time to reassemble. In this case, thanks to the construction of this guitar, it's an easy job. Bolted back on and a little glue in the appropriate places—especially on that little block of wood we found earlier on the end of the neck—and we're good to go.

Neck Reset Acoustic Guitar High Action Fix

And this is what we're looking for. The straight-edge along the frets just skims the top of the bridge. I'll need to make a new saddle to replace this one that's now far too low but that's no problem. We don't need to do any fretwork on this guitar as a consequence of the neck reset (frequently that's not the case) so, all in all, it's been a good day. 

I'll try to pull together some photos of a more involved neck reset soon. Anything with a glue-in, dovetail neck involves messy work, steaming out the neck.

For now, though, I've strung up this baby and it's sounding (and more importantly), playing great. 

I suspect this deserves a celebratory tea.