What you should know about High-Pressure Laminate (HPL) guitars

What you should know about High-Pressure Laminate (HPL) guitars

HPL, or High-Pressure Laminate materials are becoming more commonplace in guitar construction. Martin Guitars, in particular, have a line made partially, or almost completely, from HPLs. 

As a guitar construction material, there are a lot of advantages. But, in order to go into this with your eyes open, you should be aware of one disadvantage. 

Check it out…

Saving vintage guitars with clever refret techniques

Saving vintage guitars with clever refret techniques

Correcting excessive relief or neck-bow is easy with an adjustable truss rod. What about those vintage guitars made before adjustable rods were fitted, though? Are those wonderful old instruments never to be played because there's too much bow in the neck?

No way. Find out how to use levelling and compression fretting to save these guitars. 

Vintage Refretting With Bar Frets

Vintage Refretting With Bar Frets

Getting vintage-nerdy with bar frets…

I only get a few bar fret jobs a year here. And, when I’m levelling them, I generally thank the fret gods for that fact. Bar frets are a bit different to modern frets but, if you’re playing, dealing, or repairing vintage instruments, you’ll likely come across them from time to time. 

So, let’s get to know them. 

String break-angle at nut - A Primer

String break-angle at nut - A Primer

So, I want to talk about a few tips related to string ‘break angle’ — the angle the string takes over the nut or saddle. However, I reckon that it might be useful to explain what I mean and to give a little background on this area first. 

Let's start with the break angle at the nut — that's the angle at which the string leaves the nut and heads for the tuner.

Martin Guitar Non-Adjustable Truss Rods

Martin Guitar Non-Adjustable Truss Rods

In the very old days*, guitars had no truss rods at all. This wasn’t so much of a problem with gut strings but, once steel strings came along, builders realised that some sort of strengthening was required and so various things began to be inserted into guitar necks to help make them stronger. 

A while back, I realised I had a couple of Martin guitars of different vintages in for neck resets. So, with the necks off, I took a photo showing the steel rods they've used over the years. 

Martin Guitar: Surprise Dovetail Repair

It’s nice to know that guitars can still surprise me.

I guess.

This one was certainly a surprise. This is a lovely little Martin. It’s in for a neck reset. Looking at the guitar before I started, it was very obvious that the neck had already been off at some point. It wasn’t re-attached terribly well and had been shimmed near the fingerboard as if it had been over-set during a previous neck reset.

So, I didn’t anticipate everything would be factory-pristine in there but I wasn’t expecting this.

What the heck? Martin guitar neck reset throws up a surprise

Huh!? What the…

It’s a bloody-great hole. Look at the close-up inset.

Martin guitar neck dovetail in need of repair

And there’s another one around the other side.

I’m guessing what happened is that the last person to remove this neck didn’t have a good grasp on how to do it non-invasively. He or she removed the heel-cap (that little bit of wood glued to that vaguely-triangular part at the bottom of the heel) and drilled two enormous holes into the dovetail to try to gain access.

To be fair, that heel cap is reattached really well—I hadn’t noticed any evidence it had been off but it must have been.

This isn’t the best way to remove an acoustic guitar neck. Here’s how I perform a basic neck reset if you’re interested.

Make it sound

I can’t just glue this neck back in like that.

Since the holes were drilled, they’re round. A couple of lengths of dowel—slightly down-sized first—will do the trick.

Glue ‘em in.

Acoustic guitar neck repair - Martin dovetail joint

Replacing drilled out wood to repair the dovetail joint of a Martin acoustic guitar

You can See that the near dowel protrudes past the dovetail and into the continuation of the hole in the ‘face’ of the heel.


Anyway, once the glue’s dry, it’s a simple matter to cut away the excess dowel with a chisel.

Now, maybe I can get on with that neck reset. 

Martin Neck Reset - Hard

Martins are generally quite nice guitars to perform neck resets on. They're usually well made and the way they construct their instruments makes resetting a little more easy. 

Martin applies finish to necks and bodies separately and then assemble them, so there isn't the same risk of lacquer chipping and cracking when the neck is removed. Also, Martin applies glue to the interior of the dovetail joint and not  between the neck heel and body. This is more than sufficient to give a strong joint and makes it easier to disassemble. 


Except when it's not.  

Very occasionally, I'll come across a Martin that is the exception to the rule Maybe it's a Monday-morning-guitar thing but sometimes the guitar gods throw you a curve-ball. 

Check out my last post on Martin Neck Resets for the 'right' way for the job to go. I'm not going to go over all that information again—I'll just talk about that curve-ball I mentioned. 


Martin dovetail joint with a LOT of glue

Dovetail neck joint - body-end.

This neck-joint had a lot of glue.  Seriously, a LOT of glue. The arrows in the image above show that there was tons of glue on the 'cheeks'—the part that contacts the side of the guitar body. This isn't a major problem (lots of manufacturers—Gibson for instance—make this a glueing surface) but it does slightly complicate an otherwise straightforward Martin reset. If I didn't know better I'd have said this neck had already been off and re-glued but there were no signs that was the case.

Further complicating things, there was no gap at the back of the joint. There's usually a small gap between the male and female parts at the back of the dovetail and this is a nice access point to get steam in. Not so lucky here. 

I ended up having to drill a few holes to try get good penetration for the steam all over the joint. This made for very slow going. You need to be careful as you obviously can't see inside the joint until it's disassembled. 

Sometimes guitars fight back. This one took a lot of wrestling, a lot of steam, and a lot of swearing.  

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.