reinforcement

Strengthening A Repaired Banjo Neck

Glueing the heel

Glueing the broken heel on this banjo neck is the easy part. Thing is, the tensioning rod can put this glued-in section under a lot of strain so a simple glue-up’s not going to do the trick on its own.

I’ll need to help it out

Section showing how a dowel will be inserted to strengthen the repaired heel

So: Our old friend the spline. In a different form, this time.

I drilled two holes, at an angle, from the heel into the repaired section (being careful not to drill too far and out the bottom—that’d suck).

The dowel ends can be seen (the lighter ovals)

Then, I glued a couple of hardwood dowels in to the holes. The dowels protrude from the ‘good’ section to the repaired section, giving strength to help prevent that section shearing off under tension.

Back together and holding well. Time for tea. 

It's stayed in one piece under tension. Excellent.

Repairing a Nasty Headstock Break

I’ve written a bit about headstock breaks before. I get to see a lot of them. Probably ninety percent tend to fall into a category I call “Gibson-Style Headstock Breaks” and are usually relatively straightforward to repair.

The other ten percent can prove a bit more challenging, though.

That's a nasty break

This one’s nasty. It’s a ‘short’ break meaning there’s not much glueing surface to provide ‘grip’. It's also got some nasty splintering and, while the owner thought to collect some of the loose splinters, most of these won’t jigsaw back cleanly (and there are some missing).

If ever a headstock repair needed reinforcement, this is it.

Splining is one option for reinforcement but there’s too much damage here to make that a viable option (and, as an aside, the truss-rod has a pretty big ‘anchor’ that leaves little room either side of it).

Nope. We’re going overlay on this one. Again, I’ve written about overlays before (here and here for example).

The wrinkle on this repair is that there’s some serious splintering and I want to be as sure as possible.

Double-overlay, baby!

Overlay on the front and the rear.

Lots of photos follow:

As usual, I have to repair the break first to get the headstock reattached. While this isn’t too much trouble, there’s no way the repair could stand up to string tension without additional reinforcement.

Partial overlay on front of broken headstock (untrimmed)

The front first. I wanted to keep the maker’s logo intact so I removed some wood for the overlay and ‘feathered’ it towards the end of the headstock. The image above shows the inlaid overlay before the edges were trimmed.

Zoomed section shows feathering from new to existing wood

You can (probably) see in the side view photo. There’s a ‘fade’ from the existing wood to the overlay I’ve added. I’ve still extended the overlay well past the break so there’s plenty of good wood for it to grip.

Overlay trimmed and re-drilled for tuners

Above is the trimmed front overlay. The raw wood is the new section and the black headstock end is (obviously) the pre-existing section. I've re-drilled the tuner holes that were covered by the overlay. It's a good idea to do that now. If I'd waited until the back overlay was on, I'd have lost them. ;-)

The backstrap overlay. 

Now around the back. Again, I remove wood from around the repaired section and into the good wood either side. Then a new piece of wood is inlaid into this ‘lower’ section to bring it back to the height of the original wood. These glued-in overlays provide a lot of strength to the repair. 

Because the headstock is angled back, I pre-bend the overlay/backstrap before it's inlaid. Some more info on the backstop bending if you want it. 

The feathered transition from old to new is clearer here

Cleaned up around the front and applied some sealer. This lets you get a better look at the feathered edge of the overlay—the transition between new and existing.

A little lacquer tidies things up

Now we’ve got some colour and lacquer applied. Everything’s nice and tidy and, as you can see, it’s strung-up and holding. Great.

And around the back, it's looking ok too. 

Around the back and the clear finish means we can’t have an invisible repair but it’s pretty discreet.

Not too shabby, I reckon. 

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