Thursday, January 23, 2014

More Acoustic Talk -- Part Four

This acoustic guitar building project has been a great learning experience.  I've created special tools, and I'm learning how to use them.  I've assembled odd shaped pieces and shaped some odd pieces.  I've learned that sound is greatly affected by the parts and pieces used in the delivery process.  And, I'm learning there is a helluva lot of thought, planning, effort, and meticulous work that goes into this hobby.  Perhaps someday, if I live long enough, I may be able to say I'm a novice luthier.

The top, back and side(s) assembly was the last thing I posted about, which was pretty straight forward, but also tedious, time consuming and a bit mind numbing.  If I screwed this up, the game would be over . . . but, I didn't.

When the sides, heel, and tail blocks are matched up and glued, the next step in the process is to add lining (kerf) to each of the side edges.  The lining is there for stability and for a surface on which to glue the top and back.  Kerf is a finely serrated piece of mahogany, which can be easily bent to conform to the shape of the guitar sides.  Yes, it takes thirty eight small spring clamps to properly hold tension on each surface during the gluing.

It's almost time for gluing top and back onto the sides, but small vertical spruce ribs need to be glued to the sides at the upper bout, waist, and lower bout to add just a little more stability to the guitar.

I've discovered several different ways with which to apply pressure to the top and back surfaces during the gluing process, and I created different tools for the purpose, but I chose the most simple process for me . . . I like simple.  I cut a sheet of one-quarter-inch ply (it's very flexible, but sturdy) in the shape of the body mold; drilled a series of corresponding holes in the sheet and the mold.  After dropping in the completed guitar sides, I applied glue to the kerf, smoothed it around evenly, and centered the top in position on the kerf.  It took a couple minutes for the glue to become tacky enough to carefully lay the sheet on the top surface without moving the top.  Once the sheet was down, I started adding screws to the holes in the sheet, and commenced to tighten then just enough in a criss-cross manner (I learned this years ago from my grandfather, when we were rebuilding the engine in my first hotrod), until all surfaces were tightly assembled together.  This was a little tricky in that the top has a very slight arch to it.  After the top was securely glued and allowed a 24-hour cure time, I did the same process for the back.   But, the back was more delicate, because it has a compound arch to its surface, which required a whole lot more attention to alignment and movement, and because of the shape, I allowed the glue to cure for 48 hours.  You can see from the photo above how the back required a great deal of surface pressure.  

These photos show the assembled body with the top and back glued in place on the sides. After allowing the glue to continue to cure for a couple days, the overlapping top (spruce) and back (rosewood) material was removed and the edges sanded in preparation for routing a channel in each surface for binding (purfling) to be glued in place.  

If I learn nothing else, I got the lingo down pat.  ;-) 

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