Bending the Sides

Now it is on to the sides of the guitar. The sides that I purchased are also Koa. And the best part about these sides are that they actually out of the same board as the top and back so they match perfectly.

The first thing that was done was to thickness them. They are at approximately 2.5 mm thick but will be a little thinner once we complete final sanding.

What we do next is to start the bending process. This is accomplished one side at a time. First, I had to determine the "show" side of the sides and then determine what would be the butt of the guitar (the point opposite of the neck). Then we get them prepared for bending. Bending is accomplished through the use of a very nice (albeit expensive) jig.

This is accomplished through the use of heat and steam. The sides are sprayed down with water and then placed in aluminum foil (I didn't catch any pictures of this process, but I don't think it was all that necessary). Then we set up the bending machine. The bending machine has two pieces of metal alloy that cover both sides of the guitar, and a heating blanket that can "cook" the wood to approximately 500 degrees Fahrenheit. It also has a few different clamps that can be seen in the picture to the right at the waist and at both of the ends of the guitar.

The funny thing about the sides that I purchased was that there was no extra wood with it. We had one shot to make this perfect as we didn't want make any mistakes and make the need for purchasing any other sides.

After about 20 minutes of cooking the wood and another 20 or so minutes of the sides sitting in the forms, the sides are all ready to come out.

When they came out of the foil, we saw a little greenish glow to them (pictured left). This is due to the oils in the wood that have been steamed out. Not to worry, this color will disappear after sanding a bit.

Additionally, there was some spring back when the sides came out, meaning that I will have to hand bend the sides the rest of the way using a bending iron - but we will get to that.

Just to get a look at how the sides will appear when finished, you can see a picture of the sides will a little Naptha on it (the back is also shown in the lower left hand corner). You can see that there is a lot of figure in the wood still and the back and sides will definitely match when all is said and done.

Finally, after both sides have been bent, I use some spring clamps and a piece of masking tape to hold them in place over night. This is done because the sides could be slightly wet still and we don't want to worry about any more spring back.

After the sides sit overnight as pictured left, they are ready for some final bending. and getting them ready for kerfing.

In the picture on the right, you can see the rounded bending iron. This metal piece heats the wood again so that we can bend the sides to the right dimensions. The sides are soaked again with water and then placed on the iron with some pressure around the area that needs to be bent. For this guitar, the waist had some spring back, so that was my first goal. Then, each the upper and lower bout is just given a once over so that they are perfect.

The sides are then placed in negative forms so that they will be in the exact right position. Clamps are then placed at the upper and lower bout, and also at the ends of the sides. Some sand paper is used to clean up the greenish color of the wood.

It is now time to get the kerfing set up. Kerfing is the wood that is glued between the back or top and the sides of the guitar. For this guitar, I am using spruce triangles, but there are many different types of kerfing that can be used.

The kerfing is slotted so that the wood can be wrapped around the inside of the guitar. Glue is applied to the kerfing and then is clamped down using spring clamps. As you can see a lot of spring clamps are used in this process in order to keep the the pressure consistent throughout.

When the glue is dried, the sides are strengthened so much that there is limited spring back when released from the forms.

After about an hour, the spring clamps are taken off the kerfing. The sides will sit overnight in the forms so that the glue can dry.

The next course of action will be to glue the sides to the top and neck by a process called tantalloning. This process will be showed in the next week or so. Enjoy!