Guitar making tip number 177 is about gluing the braces to the plates really well. This does not mean that you need to use a gallon of glue. What is means is the braces need to be well prepared so that the gluing process is smooth. Here is the how and the why:
Gluing the Braces to the Plates
The braces themselves are very small. The surface area for gluing is small too. This means that the quality of the joint is very important. If you have some areas that are not flat, they can take away a large percentage of gluing area quickly.
When you are preparing the braces, make sure that the bottoms are nice and flat. Even on braces that are curved to arch the plates, the actual surface that meets the plate needs to be flat. This means you will not be able to see light coming through the joint when held together dry.
The better you prepare for this joint in the beginning, the less likely you will have to repair a loose or separated brace in the future. It does not take much to ensure that the braces are glued well, just a little prep work.
When you are test fitting the braces, make sure that you can’t see light coming through the joint while dry. If you can, then you have a high spot or a low spot affecting the surface. Here is how you ensure that you don’t have any light gaps…
Use a Block and a Square
When you are preparing your braces, use a square to make sure that the surfaces are being prepared well, and use a block for any sanding that you do. The block will distribute the sanding pressure, and eliminate the small dips that sanding with paper and fingers can cause. Here’s my Heirloom Sanding Block Tutorial if you want to make one.
Most makers do the shaping of their braces with a hand plane. If you can get good results using the plane, then you will get good results when you glue. However, if you are new at using a hand plane, then you can use sandpaper and a block to get the braces nice and flat on the bottoms without much trouble.
Even on curved braces, sanding them with a block is a good practice. Clamp any matching braces that will have the same radius together. Make sure that the ends are lined up well, and that they stick out of the vice enough to work them. Then, use the sanding block to true the surfaces. This will leave you with nice flat bottoms that are great for gluing.
Glue Doesn’t Fill Big Gaps
Glue will naturally fill smaller gaps between your pieces, however you should not use it for large gaps. The purpose of glue is to sink into each piece of wood a little, then harden. When the mixture hardens it becomes a solid with some of it inside each piece of wood. This creates the joint.
If you have large gaps, the glue will still penetrate the surfaces of the wood, but the big gap in the middle will not dry the same as if the pieces were touching, this results in a weak area, and can fail over time. When you are preparing your pieces, address any big gaps by sanding the brace more, and then you can glue them.
I recommend making a test fit of all your braces before you glue them down. This only takes a few seconds, and will show you any braces that need work. Simply place and clamp the brace, then check for light leaks. Clamp it the same as you would if you were doing it for real, and check your work. Don’t clamp the heck out of the brace, otherwise it can skew the results.
How to Know You Have a Good Joint
We have been talking about making a good joint, but it’s important to understand what to look for in order to understand if you have a good joint. The signs are easy to spot, and if you look for these few things along the way you can be sure that your joints between your braces and plates will be excellent.
First, do the dry run and address the light leaks. Then, apply a good layer of glue to the bottom of the brace. It’s important to cover the entire surface of the brace that will bond to the plate. Use a glue bottle to dispense the glue, and then a finger or a roller to spread it out. Make sure that the coverage is good, and that none of the glue has started to harden.
Clamp the piece, and look for some squeeze out. A little squeeze out is important. If your glue runs like a wild river, then you applied too much in the last step. However, you should see a small even bead come out of the joint. When you see this, it’s an indication that the glue has been pressed around under the joint too. This means even coverage, and a strong joint.
Be sure to wipe the excess away before it hardens, which will be much easier.
1,001 Acoustic Guitar Making Tips for Beginners
Tip No. 177 is from my book, 1,001 Acoustic Guitar Making Tips for Beginners, which has a thousand more great tips to get your first few builds on the right track. There is no secret to guitar making, just a lot of small things that you need to get right. These tips will help you.
If you have any questions about Guitar Making Tip No. 177, please leave a comment and I will be glad to answer them. Also, please Subscribe so that you don’t miss out on anything new. Happy building.