This is How to Make an Acoustic Guitar – Part 32 – Attaching the Neck. In this part of the series I’ll show you how to attach the completed neck to the completed body. This is where the guitar finally becomes one piece. Enjoy.
Attaching the Neck to the Body
Attaching the guitar neck to the body is the last step before all of the pieces finally become one. This is where you’ll finally be holding in your hands a guitar that is pretty darn close to actually functioning.
This is also one of the steps that is a bit of a hangup for new makers sometimes. There are a lot of different schools of thought on making a neck to body joint on the guitar, and all of them have some merit.
The biggest thing is not to be overwhelmed by the choices, and the sometimes very strongly written arguments for or against a particular type of joinery. There’s more than one way to do anything, and just because it’s different doesn’t mean it’s wrong.
If you missed last week, check out How to Make an Acoustic Guitar Part 31 Here.
Joinery Options for the Neck
The four primary methods of joining an acoustic guitar neck to the body are a dovetail joint, a mortise and tenon joints, a dowel joint, and bolts and inserts. Each of these are good for several reasons, and it’s really a matter what you’re comfortable doing.
The single dovetail joint is the bread-and-butter of guitar makers. It’s the oldest joint ever used, or at least one of them, and it’s very sturdy for a number of reasons. If you’re comfortable doing some carving, or you make a template, it’s a good choice.
Next on the list in no particular order is the mortise and tenon. This is similar to a dovetail except the tail piece doesn’t flare out, and it’s more like a rectangular chunk and a rectangular opening.
This creates a larger amount of gluing surface, which increases the strength of the joint. You can also add pins to the mortise and tenon, and create an even more secure joint.
Next is dowels and glue. A dowel is nothing more than a floating tenon. You can put a couple or a few dowels in between the two pieces, and glue them together. Even though this is a little less common, a floating tenon is the third strongest joint in all of woodworking.
Finally, bolts with threaded inserts is starting to become a little bit more popular as a way of attaching the neck to the body. The primary advantage is that if something were to happen, you could easily detach the neck from the body to fix it.
No matter which way you choose, simply do something that you’re comfortable doing. The more comfortable you are, the better it will turn out, and consequently the better your guitar will turn out.
See Also: Acoustic Guitar Making For Beginners
The Most Important Thing to Know About the Joint
In the end, the absolute most important thing you need to know about this joint is that it needs to be strong. You can lose a lot of vibration from the strings through this neck joint, so the stronger and more solid the joint, the better your guitar will sound.
Imagine if you had a rubber gasket in between the neck in the body on a guitar. As you play the guitar, so much of the vibration will be lost and absorbed by that gasket. It’s an extreme example, but a week neck is just as bad as some small percentage of a rubber gasket.
Take your mind off of the actual method for a minute, and just focus on strength. Do what you’re comfortable doing, and make that joint strong. You’ll be happy that you did.
See Also: The Secret to Guitar Making
Using Dowels and Glue
Since this guitar is made with dowels and glue, that is the joining method I’m going to demonstrate. The process itself is very straightforward, and it creates a strong joint that holds the neck and body together really well.
In order to do this method, you’ll need a set of dowel points, a matching drill, and matching dowels. You can buy these purposely made for this task in a kit, or you can buy your own dowel rods and drill yourself.
I recommend the kit, because everything is sized to work together perfectly. You don’t have to worry about tiny variances in diameters, and it’s just a lot less to deal with when you’re working on your guitar.
See Also: The Last 10% Principle for Woodworking
Drilling the Holes with Dowel Points
The first thing that you have to do is drill holes on your body for the dowels that will be used to attach the neck. I recommend a minimum of two, and as many as three holes positioned uniformly to spread out the load.
I also recommend using dowels that are at least half an inch in diameter. Anything smaller is not really providing a lot of strength, and anything bigger is a little too much. Half inch seems to be perfect for this size of a joint.
You need to drill the holes as straight as humanly possible. Also, drill them all into a depth that is slightly over half the length of the dowel itself. This is to prevent it from being pushed all the way through when you join the neck to the body.
Once the holes are drilled, insert the dowel points and line up your guitar neck with the body. Using a mallet, bump the heel of the neck against the dowel points, and it will transfer the marks to the neck.
Using those marks as a guide, drill your corresponding holes to the dowels that are on the body, and it will line the two pieces up perfectly. Again, don’t drill any farther than half the length of the dowel, and definitely not deep enough to pop out of the heel.
Doing a Dry Run
Once you have everything drilled, it’s time to do a dry run. The dowel system has to be done accurately in order to work. So, it’s important to check the accuracy before you actually do any gluing.
Insert the dowels in either the guitar end or the neck end, and then press the two pieces together. You may need a mallet or a clamp to get the pieces fully mated. Once you have them together, inspect the alignment of the joint.
If everything looks good, you can proceed to the next step. If there are problems, address them now. It could be as simple as shaving a tiny pinch off the side of one of the dowels to get the fit to be perfect. Whatever it takes, make sure the fit looks good.
See Also: Practical Acoustic Guitar Making Advice
Alignment and Gluing
It’s really important to a check your alignment, make sure that the neck is straight. After all, the strings are going to go straight from the head stock to the bridge, and if the neck is angled, it’s going to look weird.
This is still part of the dry run. Sight down the guitar a couple of different ways, and then also use a straight edge to ensure that the neck is pointing straight down the middle. Since the bridge is glued on last, you can make up for a couple millimeters if you make a minor mistake.
When you’re happy with the alignment, and you know that it’s going to be right, you can proceed to gluing everything together without having to worry nearly as much about having to deal with any big problems this late in the game.
Clamping the Neck to the Body
Make sure that you figure out your clamping method before you put any glue on the joint. This is actually a pretty awkward place to clamp, so either plan for some long bar clamps, or some method of wrapping the guitar to hold the pieces together.
Most of the time, the dowels will create a pretty tight fit. Once you add a little bit of glue, they’ll swell up a little bit, and then it will be even tighter. Typically, one bar clamp should do the trick of holding them together long enough to dry well.
Another thing that I’ve seen creative luthiers do is plan for this clamping issue and have a pre-drilled and piloted wood screw that can be turned in place from inside of the sound hole. This is a temporary clamp essentially, and it holds the two pieces together while the glue dries.
Coming Up Next Week
Next week, the how to make an acoustic guitar series rolls on to making the bridge. This is the last part that needs to be made before the guitar can be finished and then set up. It’s a fun little part of the project, and I’ll show you how to do it easily.
You definitely don’t need to buy an acoustic guitar bridge. It’s easy enough to make, and the piece of wood you’re going to use is so small that it’s also inexpensive. Of course, I’ll share plenty of tips and tricks along the way.
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