Installing the Back

Monday, June 29, 2009

The facility where I work is shut down for the July 4th week and my poor wife does not get that luxury, so I get to spend a whole lot of quality time working on my mandolin.

Today I got to glue the kerf lining and the back on.

Similar to the way I aligned the soundboard when I attached it to the sides, I started by installing three alignment pins. These pins, located in the head-block, tail-block and lower point block, are actually just small nails that have been cut off and put in backward so that the point goes into the back when installed.

First I drilled the holes. The bit for this is just big enough to allow the nail to be pushed in by hand - it doesn’t need to be really tight.

Then I inserted the nail (point first) all the way to the bottom. Using my handy linesman’s pliers, I cut the nail as close to the block as I can. Because the cutters in the pliers are inset from the face closest to the wood, I know that the remaining nail will be a little long - just like I want it.

Then I pull the nail out of the hole, flip it over so that the point is up, and tap it securely to the bottom. Now, when I get the back exactly aligned with the sides, all I have to do is squeeze the two together. This will force the nail points into the back wood and give me repeatable locating holes. The nails, of course, are now permanent parts of the mandolin.

Next, just as I did for the soundboard again, I glued in my kerf lining and then once it dried, I sanded it flush with the sides.

Here is the last shot (hopefully) anyone will ever have of the inside of this soundboard.

At that point, the only thing remaining before gluing on the back is to give this sign the inside of the back so that one day, when I am dead and famous, the proud owner of #1 can prove who built it.

And now, because the internet will live forever, there is documented proof of just what it reads.

Ok. Enough of that. Back to the building thing.

As I pointed out earlier in my various attempts to use hot hide-glue, it sets-up really fast and anything that can be done to get clamps in place quickly is valuable. So in preparation for gluing the back on, I started by cleaning everything off of my workbench, dry-clamping the back to the body, and then laying out all my Bessie clamps and cello clamps so they are ready to go. Here is how it looked while I was heating the hide-glue (far left of the photo).

From start (applying the glue around the perimeter of the body) to finish (tightening the last cello clamp) took only 5 minutes. Fortunately, during my dry-clamping, I found that I could strategically apply four Bessie clamps and five cello clamps to close all the major gaps and then come back to add the remaining cello clamps. I believe I had these first nine clamps on in just over 1 minute. Here is how it looks while drying.



I’m going to let this dry over-night and then, maybe as early as tomorrow, I will use my belt sander to sand down the edges of both the soundboard and back to match the sides (both are oversized now) and get started installing binding around the body and peghead.