Showing posts with label Kerfing. Show all posts
Showing posts with label Kerfing. Show all posts

Saturday, February 1, 2014

Fitting the Back

Perhaps there's some aspect of successfully fitting the back that represents a significant milestone along the way to completing a guitar, or maybe it's just that I've repeated this part of the process enough times that I feel confident in the outcome and have come to enjoy the sensation and sound of the back braces clicking neatly into their pockets. Whatever the reason, it's a part of the build process I look forward to and derive great satisfaction from.

To reach this milestone - assuming that the dome of the back has already been sanded into the rims - I carefully align the back with the centres of the head and tail blocks, then mark the sides where the brace closest the the tail block will intersect them. I lay a steel rule across the guitar to join the corresponding marks, and pencil the line of the braces onto the top surface of the linings. 

As a precaution against chipping, I make a saw cut equal in depth to that of the brace end on the side of the pocket likely to be chipped by the clockwise rotation of the bit. I hope the right-hand photograph below shows this clearly.


With a spiral downcut bit mounted in the Dremel and carefully adjusted for depth, I rout the first pair of brace pockets, using the pencil lines as a guide. If the marks were placed accurately, the braces slip into place with just a hint of resistance. I check the fit of the back and widen the appropriate brace pocket to compensate for any misalignment. Once I'm happy with the fit and alignment, I can mark the next pair of brace pockets, confident that the alignment of the back will be more securely and accurately established as I proceed. When the four pairs of brace pockets have been prepared and the back fits perfectly, I can allow myself a moment of self-congratulation - before I remind myself that it's really only a minor triumph and that there's plenty of work ahead of me!



Cheers
Pete

Tuesday, January 28, 2014

Kerfed Linings

I've fabricated kerfed lining strips from mahogany in the past, and while that's a popular and appropriate choice, on this guitar I was in the mood to use linings that closely match the colour of the spruce back braces. Spruce doesn't exactly grow on trees in my neck of the woods (puns intended), so I substituted Jelutong - a lightweight, light-coloured South East Asian hardwood species that serves this purpose well.


After bandsawing and thickness-sanding the strips, I set up a crude but effective jig on the bandsaw that helps me cut kerfs of a consistent spacing and depth. I leave a little more wood between the extremity of the cut and the opposite face of the lining than it seems is common with the off-the-shelf product, and the strips I prepare are a little more robust as a result. If there's any trade-off, it's that I feel the need to pre-bend the waist and upper bout portion of the linings on my bending iron prior to gluing them in place, more as an added precaution against breakage than out of any real necessity. 



A pet peeve, and the motivation for devoting a little time to preparing my own snap-resistant kerfed linings, is seeing an otherwise carefully crafted instrument whose linings are joined at some point, particularly when such joins are in plain view through the soundhole. Sacrilege!




Cheers
Pete

What's In a Name?

The back and sides of this guitar are of narra, which is an alternative name for a wood that's most often marketed here in Australia as ...