peghead

Guitar Neck Repairs: Splines

Headstock repairs are nothing new in these parts. If you pop by the Haze blog from time to time, you'll probably have seen more than a couple over the last few years. We've also talked about the need to reinforce some broken headstocks with a 'backstrap' (a piece of wood that overlays the repair to add strength).

I like backstraps. They're an effective and discreet way to strengthen a neck repair. They can take a bit of time and effort to do properly, though, and splines are not the only game in town. There are times when an alternative is preferred. 

Splines are the prime candidates.

Spline Headstock Reinforcement

A spline is a slat of wood that's inlaid into a channel cut in the neck.

Like this:

Reinforcing a broken guitar neck repair with splines.

The idea is that the channel runs for a distance either side of the repaired crack. A slot is routed and the spline glued in. The newly inserted 'good' wood of the spline ties together the good wood on both sides of the crack.

As you might expect, the splines are carved down to match the neck and the finish touched up. Splines are not quite so inconspicuous as a well-executed overlay but they are an excellent way to bolster a neck repair that needs some reinforcement. 

And, in the right circumstances, you can even get inventive in your splines

 

Headstock Repairs - More on Reinforcement

So we've looked at a neck repair with an overlay for reinforcement. Let's have a look at the other main method of reinforcing a broken headstock: Splines. In guitar repair circles, splines are long (relatively speaking) narrow pieces of wood that are glued into corresponding channels to provide additional strength.

Failed, previous repair

Nasty glue residue on failed repair

The first repair is the important one.  

Remember these wise words. If the first one fails, it usually complicates any subsequent repair. This guitar arrived in the workshop with its headstock flapping about, held on by only some gummy bits of glue. There was a LOT of residue to clean up. Too much, really. Any glue I apply to repair this break needs to make a good contact with the wood. New glue, trying to grip a film of old glue is a recipe for a poor repair.

Even after cleaning up much of the earlier stuff, I felt some reinforcement was necessary to ensure a sound and lasting repair.  

Determining the truss-rod location with a magnet

Glueing up the peghead before splines

As it happens, the diamond-style volute on this instrument provided me with the perfect idea for reinforcing things. I can rout a channel through that and carve the spline to the same diamond shape. Nice and discreet. Splendid.

First up, I have to keep the truss-rod in mind. I don't want to accidentally rout into a hunk of metal. The magnet on the back of the neck tells me where the rod ends. I note that and get on with getting things back in one piece.  

Diamond volute to be 'splined'

Inset, rough-cut spline

You can see the diamond volute pretty clearly above. I'm not going to take the whole diamond—I'll effectively rout a channel through it and farther along the neck (past the break). 

It's an easy job to shape a piece of mahogany (the spline) to fit this channel. Then a little carving will replicate the original shape. Clean up, slap on a bit of lacquer and we should be able to avoid any more strings of gummy glue.

Spline reinforcement on guitar neck break

Headstock Repairs - Reinforcement

Broken Gibson headstock repair

We've talked a lot about neck resets over the last few weeks so let's move down the other end of the neck. Headstock breaks.  

Nobody likes to see it happen but sometimes your guitar takes a tumble and the impact can—all too easily—snap the headstock. In most cases, this is a (reasonably) straightforward repair and can be re-glued soundly.  

Sometimes, though, the nature of the damage can force us down a more 'involved' path. If the break is 'short' (i.e. it doesn't provide a lot of glueing area to ensure a sound repair) it may be necessary to consider some reinforcement to ensure the repair holds.  

One solution is what's called a 'backstrap overlay'.  

This involves overlaying some fresh wood over the repaired break. The new wood glues onto the unbroken wood either side of the crack to add strength.  

Let's take a look at one. 

Reglue headstock before applying backstrap

Remove wood to accept overlay

In the first photo directly above, I'm repairing the break. This might seem odd but I need to get everything back together properly before I apply any reinforcement. The repair is carried out as it would normally be since the actual re-gluing isn't the real problem—the problem is keeping it in one piece after string-tension is applied. I need to glue-up everything as normal and then reinforce things to ensure the repair is strong.

When the initial repair is done and the glue has dried, I can begin the real work on this one. I remove a few millimetres of wood from the rear of the headstock and, past the break, along the neck. It would make for a more discreet repair if I brought this all the way to the end of the headstock but, on a Gibson, I like to stop short of the serial number. If the guitar is ever sold on, a perspective buyer may be put off more by the lack of a serial number than a well-executed repair. 

The photo above on the right shows the removed section. I'll inlay the new wood here so let's get on with that.

Clamping for backstrap overlay on Gibson neck break

New wood overlaid over broken neck

The wood to be overlaid on the headstock is thicknessed and cut to the rough dimensions. To accommodate the angle between headstock and neck, I bend the new wood. It's this bending that adds extra strength to this repair as the wood grain curves to the correct angle.  

Repairing guitars often makes for some intricate clamping setups and overlays are prime culprits. A shaped caul is useful to get the wood in that curved bit glued in properly. The roughly shaped wood overlay is pretty obvious (and pretty ugly at this stage) in the photo on the right. 

Newly inlaid wood cut to shape on headstock

Tuner mounting holes drilled in overlay

This is where things take shape (pun intended). The overlay is cut to shape and the tuner holes drilled.  

At this point I can go through the usual finish prep. Grain-filling, sanding, etc. In cases like this I need to match the colour of the original finish on the newly overlaid wood. I also have to manage the transitions between new and old finish carefully to keep things looking as inconspicuous as possible. Sealer, colour, and a number of clear-coats later and I'm ready for the next step. 

Waiting.  

Have to wait for the finish to cure properly. Then sanding and buffing and polishing and reassembling and stringing-up and… 

Playing. 

All is well with the world.  

Gibson headstock break repaired with backstrap overlay

Les Paul neck repair with reinforcement

Reinforcing A Broken Headstock

SG Broken Peghead Repair

A while back, I outlined a (slightly) unusual method of repairing the broken neck of a Gibson SG. I mentioned that guitar would make another appearance soon and here it is. The guitar suffered a broken headstock while still in its case. A neck-break in the case was the final straw for the owner—who's had more than one Gibson require a neck repair— and he wanted to consider options to help prevent it happening again. We talked over the pros and cons of the various solutions and eventually decided on a backstrap overlay.

This methodis sometimes used where the break is too nasty or offers insufficient glueing surface to guarantee a sound repair. A backstrap was not a necessity to repair this particular break (and, indeed, it entailed additional expense to carry out) but the owner wanted to do something that would go towards preventing a reoccurrence.

Illustration of backstrapoverlay

Illustration of backstrapoverlay

A backstrap overlay involves removing some wood from the rear of the headstock and some way past the broken section. A patch is cut from new wood and is bent to conform to the curve between headstock-angle and neck. Because the inlaid patch has been bent to shape, its grain has no run-out and remains strong.

I explained to the owner, and I will to you, that this offers no guarantees. However, this method of applying bent wood certainly strengthens a weak area of the guitar and it will be stronger than the original.

Backstrap peghead repair
Headstock repair backstrap overlay technique

The first thing that needs to be done is to repair the existing crack. I've discussed this in a previous post so I'm not going into any detail here. A repaired crack is necessary so that the section to accommodate the backstrap can be removed. My usual preference, when doing this, is to run the strap right to the end of the peghead as the inlaid wood is more discrete. In this case, doing so would have removed the serial number and 'Made in USA' stamp and I decided keeping these better served the future value of this guitar.

A 3mm section is removed from the back of the headstock. The Saf-T-Planer allows me to do this cleanly right up to the point the neck angle gets in the way. The remaining section along the neck is removed with hand tools.

Bending wood for broken guitar neck repair
Repair patch for broken headstock

A piece of mahogony is thicknessed to the appropriate size and cut out roughly to shape. Out comes the trusty bending-iron and I work the wood into a gentle bend to conform to the section I've cut in the neck.

Clamping backstrap overlay on broken peghead repair
Reinforcing weak neck on Gibson SG

Some inelegant, but effective, clamping and glueing and the backstrap is in place.

But it's not pretty. The patched in piece does allow you to get a look at the bend clearly though. Because the grain in that patch (backstrap) runs—uninterrupted—from end to end it's much stronger than the piece that was removed.

Neck repair on Gibson SG
Completed SG headstock repair

A little work with routers, drills, knives and sandpaper and the new piece looks a little more like a headstock should. Some touch-up work helps hide the evidence. A (relatively invasive) repair like this can never be completely invisible under a translucent finish but this is pretty discrete.

We've repaired and strengthened a broken-necked SG and preserved the serial number. Not a bad few day's work.

Cross-posted to Guitarless