Guitar Making Tip No. 143 is about checking the center seam. When you join your plates, you need to prepare the edges really well. This means no light leaks. Here is how you can prepare your top and back plates for a great joint.
The Center Seam on the Top and Back Plates
Not only does this conserve on materials, but it also makes the top and back plate look a little better because of the match. The two boards are book matched, making them a mirror image of each other.
This matching grain adds to the look, and makes the guitar pop, especially on the back plate. The top is going to look about the same since most tops are fairly simple looking. It’s the back plate that really looks amazing when you match a great looking piece of wood. No matter the look, you need to check your center seam so that you have a great joint before you glue the plates together. Here is what you do…
Checking the Center Seam for Light Leaks
When you joint your wood for the top or back plate, test the joint. Hold up both pieces, and press them together at the center joint. Then, hold that up to a light source. Look at the center seam, and see if you can see light coming through.
If you see none, then the process is over. You won, and you can move on to gluing. If you do see light, then it’s time to make some adjustments. Depending on how you made the joint, you may only need a little work to get it perfect.
Those of you using power tools can simply run the edges through the jointer or jig one more time. If you are working buy hand, work on the edges again. Once you have them perfect, you can go on to gluing.
Using a Jig for Making the Center Joint
It’s easier to get the edges of the boards perfect when you use a jig. Making Jigs is an important part of woodworking and guitar making, and they make the process easier and more accurate. If you are new to guitar making, you should make a lot of jigs.
The center joint is going to be about 21 inches long, and only about 1/8″ thick. This seems like only a little bit of wood, but it can be difficult to make straight. When you use a jig, the process becomes easier.
There are a number of jigs for making the center seam joints. It’s easiest to just use a jointer, but if you do not have that tool, making a jig is cheaper. You can also use a simple router with a flush cutting bit along a straight edge, and that will work too.
Making the Joint the Easy Way
Fold over the boards like closing a book, and work them both at the same time. When you work both pieces together, you don’t have to worry as much. Since the pieces are going to be opened together and glued, a slight angle to the edge will work itself out.
It’s a case of geometry, but when you flip open the boards, the edges are still going to add up to 180 degrees. This means if there is a slight angle when stacked, it will still lay flat when opened. Don’t think about it too much, just close the pieces like a book and work the edges as the same time.
Once you are feeling good about the edges, open the pieces like a book and look through the center seam joint into a light. If you can see light, try working he edges again. If you always see light in the same place, look at your setup and check for errors before trying again.
Guitar Making Tip No. 143 Wrap-Up
When you are making the center seam on your top or back, you need to create a good joint between the pieces. One way to check your joint is to look through the center seam and see if you can spot light coming through.
When you cannot see any light, you are done. Move on to gluing. If you can, then you need to try a little harder on your center seam. Look into some jigs if you are struggling, and take your time. A good joint is possible, even if it takes a little extra time.
If you have any questions on Guitar Making Tip No. 143 – Checking the Center Seam, please leave a comment and I will be glad to answer them. Happy building.
1,001 Acoustic Guitar Making Tips for Beginners
Tip No. 143 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.
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