This is How to Make an Acoustic Guitar Part Twenty Three, Covering the Rod. In this post I’ll show you how to cut and fit a cover for the truss rod inside the neck. Enjoy.
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Covering the Truss Rod
Once the truss rod cavity has been made, the rod itself will sit a little bit below the top of the channel. The rod also angles downward slightly and sits lower in the channel near the heel than it does near the nut.
This extra space on top of the truss rod needs to be filled, so that the truss rod is held in place firmly. This is what helps the rod work properly, and is a necessary step in the installation process.
Thankfully, filling the slot is a straightforward process and you can use scraps to do it. I’ll show you everything you need to know, and filling up your trust rod slot will be an easy process.
If you missed last week, check out How to Make an Acoustic Guitar – Part Twenty Two
Checking the Slot for Fit
The first thing that you need to do after you create the slot is to test fit your trust rod and see how well you did. If you took your time and worked carefully, odds are the slot is a very good to perfect fit for the rod.
If there is a little bit of wiggle room, don’t worry, because there are things you can do to make the fit perfectly. Depending on how much wiggle room you have, take a look at some of the different materials you have in the shop.
If your rod fits with only a tiny pinch of wiggle, a piece of the veneer on each side might be all you need to make it snug. If the wiggle is more than that, it may require a couple pieces on either side.
Also, if you have wide and arrow sections on your rod, you can slide pieces of binding strip next to the narrow sections and that will isolate any rod movement. Again, the goal is to keep the truss rod centered in the slot the entire time.
See Also: Acoustic Guitar Making For Beginners
Wedging the Rod for Twisting
Another thing to look after when you are doing your fitting is that you don’t allow the rod any movement to twist. The rod functions by pressure, and the pressure comes from turning a nut. Sometimes, this can cause the rod to try and twist.
Pay particular attention to the tip of the rod that is closest to the nut. Make sure that this area is wedged in carefully, and doesn’t have the ability to twist or move. This is where a little bit of veneer or extra binding strip material can be helpful.
You want to do everything you can to make sure that when you tension the rod, it pushes directly backwards against the tension of the strings. Any twisting or turning will not straighten the neck as intended.
Milling a Slot Cover
Once you have the rod itself fitted really well, it’s time to mill a cover that will hold the rod in place. This is simply a piece of wood of the same species and grain orientation as your neck, and you cut and fit it into the slot.
Due to the way the rod is installed, the cover may not extend the entire length of the slot, and might end up stopping a few inches before the end of the rod nearest to the nut. This is OK, sometimes it will cover and sometimes it won’t.
Start by cutting a piece of wood the same length as the truss rod slot and then milling it down to the same width. If you milled the slot well, you should have nice straight sides that make it pretty easy to fit a board down in between them.
Fitting and Gluing
Once you get the fit rod, cut off a quarter-inch from the main board, and carefully glue that in piece in the top of the truss rod slot. The big thing to be careful for in this step is that you don’t load the truss rod channel with glue.
In reality, this little strip of wood is only hanging on by the top inside edges of the truss rod slot. This means at the thickest it might be an eighth of an inch, and at the thinnest it could be like paper. It’s not a lot of wood.
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Even so, you don’t need a lot of gluing surface to hold in such a thin piece of wood. Carefully coat the sides of the truss rod slot, just above the rod itself and no further down. Then, press the cover in place and slide it back-and-forth to spread the glue.
Apply some clamps to hold the cover down, and then allow it to dry overnight before removing them. After the glue has fully cured, you can move onto the next step.
Flushing Out the Truss Rod Strip
Check your glue joints to make sure that the strip was glued in nicely, and assuming everything went to plan, grab a chisel or a hand plane and start leveling the strip to the same height as the rest of the wood on the neck.
Be super careful in this part of the operation, because you don’t want to take any wood from the surrounding area. It’s all about just removing wood from the cover, and bringing it down level with the rest of the board.
If you accidentally remove wood from the surrounding surface, you could end up with a problem where your fretboard doesn’t sit flat anymore. That gap can end up being visible, and it just takes away from the look of your guitar neck.
When planing this strip, if you do run in to a situation where you take too much, simply leveled the entire neck surface where you would glue the fretboard and that will reset you back to zero.
Tips and Tricks for the Rod Cover
Though this is a fairly straightforward process, there are some tips and tricks to remember that can help you install your rod cover easily.
- Don’t hose the channel with glue, because a glued truss rod will not operate.
- Select a piece of wood that’s the same species for the slot cover as your neck species.
- Clamp the cover in place, but don’t clamp so hard that you mash the rod.
- The more you cut off of the rod cover before gluing, the easier leveling it will be later.
- The better you make your trust rod slot, the easier it will be to cut the cover.
- After you level the cover, check to ensure you don’t have a hump in the middle.
- Since the gluing surfaces are very small, allow the cover to dry overnight.
Coming Up Next Week
Next week will turn our attention to the fretboard. For this guitar, I used a pre-slotted and radius fretboard that I bought already milled. The price difference is only a few dollars, and it saves a lot of time to buy the board already milled.
In this part of the guitar making series I’ll show you how to install square inlays using epoxy and a chisel. I’ll show the entire process by hand, which is actually a lot faster than it sounds.
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