Guitar Making Tip No. 282 is about carving all of your back braces at once. Most of the time, the back plate has a similar arch. This is where the braces slightly bend the back. If your design is the same on all braces, just carve them at once. Here is how.
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Acoustic Guitar Back Braces
There are typically four back braces on an acoustic guitar top. There are two that are easy to see through the soundhole, and then two more that are deeper in the body.
They are separated by thin strips of Spruce, that reinforce the center seam.
The bend on the back plate that makes the dome is there for a couple reasons. One being that it helps the structure, and another for sound. Finally, it also makes the back plate look domed rather than concave. A flat back can look indented rather than flat, so the doming helps with that as well.
Since the dome is typically 1/4 inch or so over the width, save time by carving that arch on all the braces at the same time…
Prepping the Braces for Carving
Cut all of your back braces to the same length. The width will be different depending on your design, and then lay them next to each other in order. Start with the brace that will be closest to the head block on the left, and end with the brace near the tail block on the right.
Now, you need to tack glue them together. This means you need them to stick and hold, but also come apart later on. There are a few different ways to do this, and if you are not used to this technique look online and find a couple different ways so you can pick your own.
My way is to use a tiny drop of glue on the faces near the ends, then clamp them together. This is an easy glue joint to break, and I cut my ends a little longer anyway, so if need be I can cut them off and still have enough material to make the longer braces.
Carving the Arch on the Braces
Now that your braces are tack glued together, they act like one billet of wood. Turn it on a side, and mark out your arch profile on the side of the brace. Then, flip it over and do the same thing on the other face.
Now, clamp the brace billet into a vise so that you can use a hand plane. You need to clamp it down so you have access to as much of the wood as you need to carve off the material that you need to remove.
Start removing material with the hand plane or chisel. As you get close to the lines, start using a small square to check your progress. As you taper each end, use the square to make sure that you are not carving any lumps.
Final Shaping of Your Braces
When you are really close, it is a good idea to switch tools. Make your checks with your square, and when you are really close, you can switch. I recommend a sanding block with 80 grit paper or 100 grit paper.
Use the sanding block in long strokes. Be careful near the ends so you don’t roll them over, which can be easy as you drop off with the sanding block. Make long strokes, and aim to blend the pieces together.
Think blending the entire time, and you will do the right kind of work. Carefully sand end to end, blending the surfaces together. Check with the square as needed, and don’t stop working on it until you are happy with the results.
See Also: Woodworking Tips Cards – Sanding Blocks
Taking the Stack Apart
When you are done carving and sanding, now you need to take the stack apart. This is done easily using a thin knife. Insert the knife between the braces near their centers, and then slide the knife out towards the ends.
Some of the glue joints will let go really easily, and some will fuss more. As long as you don’t blow out any huge amount of wood you are fine. Even if you do, think about the final shape of that brace in your mind, because you may be carving that part off anyway.
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Most of these braces are going to lose all of the wood near the ends in the carving process, so if you do break off a small chunk of wood, don’t worry. As long as you can get a clamp on there to glue it down to the back plate, you are fine.
Your homework is to try carving the arch on your back plate braces at the same time. It’s easy, and it will save you a ton of time over doing the same process individually. You will also get better results, because the braces will be more square.
When you carve something that is really thin, it can be difficult to maintain a square face. The brace bottoms need to be square, otherwise the glue joint to the plate will be poor. Making the blank wider is one way of making the process easier.
Since you have braces that are closer to square, your process for gluing them down is easier too, and you will make less errors. There are a lot of secondary benefits to carving the arch at the same time, and you should give it a try at least once to see if you like it.
Guitar Making Tip No. 282 Wrap-Up
Guitar Making Tip Number 282 is about carving the braces together. Since most of the time there are only four braces, and they have the same taper on the ends, carving them together makes perfect sense.
Simply tack glue the ends, and draw your profile on the stack. Clamp the block so it can be carved and go to work. Start with edged tools and then move to sanding or scraping tools when you get really close to the final level.
After that, take the braces apart, and you can cut them to final length, then install. The gluing process will be easier too, because it is easier to maintain a flat bottom on the braces when they are in a wide stack instead of individuals.
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