Class 3 Thursday Night (9/11)

The Agenda for the night was to finish radiusing the guitar's back. Attach Kerfing to the back, Radious the front to a 15 foot radius, and attach Kerfing. Then construct our side bracing and maybe even bracing for the top. We had quite a bit of planing and sanding left to do on the back. We made three mistakes. The first was we planed one side down to far. This meant we really had to reduce the heel and end block also. When we planed the Neck Block, we planed it straight across instead of at an angle, but this was corrected by planing on an angle. The third was I slipped while planing the block and cause a small crack at the side running with the grain. It was fairly small but if unattended the crack could run further. So a little super glue and accelerant and we good to continue sanding. We finally got to where we thought we needed to be and started the Kerfing.

Kerfing is used sort of like a shelf.  I runs along the sides of the guitar and will provide the support for where the top and bottom meet the sides.  Kerfing feels almost like balsa wood. Our back Kerfing was Mahogany and our front was Maple. Very thin and light weight. It is heavily scored so it is really flexible but very fragile. 1st order of business it to measure from Neck to Heel Block the amount of Kerfing we would need. To do this you have to run the Kerfing inside around the grooves from Block to Block which is what Cian is doing in the picture above. The first time we tried to do this we promptly snapped the Kerfing...

There is a trick, if you lightly clamp in on with clothespins,and let the clothespins do the bending for you it is possible to do without breaking it... Not easy but possible.

Once you have the right amount of Kerfing you are ready to glue it. You apply a thin layer of glue on the back. Not enough, it won't be strong, too much and you will get a lot of 'squeeze through' which is difficult to clean up after. Once you have glue on your Kerfing, using your high tech glue application device (finger), you gently squeeze the Kerfing to the side while applying a high tech force distribution device (clothspin with a rubber band wrapped around it) you work your way around the side. You are watching to ensure the Kerfing makes clean contact with the sides, clean the glue squeeze out and ensure the Kerfing is a 'scosh' above the side. We will be radiusing the kerfin to match the sides at some point.

Here is the back side, Kerfing glued and clamped.  It takes about 30 minutes to dry which we used to start our side bracking.  We found some nice scrap Maple and measured and cut those.  Sanded and Radiused the Front along with glueing the Kerfing and had to call it a night.