Acornhouseworkshop

The guitar is out of the finishing room(s) (I had to do the last couple of coats for the body at school, since it got too cold to do finish in my unheated garage). It got extended when I discovered that turner’s tape is NOT the tape to use, when a wiping varnish is being used. Last year I had used regular double sided carpet tape to attach my bridge mask, and had no problems. This year, I used double sided turner’s tape, which reacted to the varnish, causing a halo around the bridge mask that wouldn’t cure. I’m guessing they both use the same solvent (mineral spirits), and the adhesive was leeching out. So, I had to take off everything except the green painter’s tape, which was the bottom part of the mask, and sand down close to bare wood. Then, a few more coats, and the top was finally finished.

I gave the varnish a couple of days to cure, and then used my micro mesh pads to sand everything down to 12000 grit, putting a nice shiny polish on everything, and making the neck silky smooth. Not quite the mirror finish that a big buffing wheel and numerous polishing compounds will give, but ok. I like the more natural look with actual wood grain showing, rather than the plastic look of a filled and featureless surface. (Of course, I don’t have a big buffing wheel and polishing compounds.) The next step was to bolt the neck on and glue the fingerboard down. The tenon gets no glue. So when the time for a neck reset comes (which it will on all guitars), the only glue to deal with is under the fingerboard, which is no big deal. The nut was also cut to length and shaped and glued in with CA glue.

Then the bridge. Before glueing the bridge, it’s bottom has to be contoured. Remember, the top is not totally flat, there is a very slight arch. So the bridge, with its flat bottom, needs to match that arching, or it will not glue down solidly without creating a stress area for the top, acting against the arc of the bracing. Which will lead to premature failure. Some vigorous sanding with 100 grit paper takes care of the arch, and leaves a rough bottom to the cocobolo, suitable for glueing. (Since cocobolo is an oily exotic wood, it needs it’s oiliness tempered before glueing, with either acetone, or a fresh sanding with coarse paper. I prefer sanding, since it leaves a lot of tiny nooks and crannies for the butter…I mean, glue.) The top of the bridge gets its final sanding down to 12000 grit (never a finish on it for steel strings.) Then I put down some more green tape to get reference lines. The bridge has to positioned exactly, for good intonation, doubling the distance form the nut to the twelfth fret, and adding 2mm to the distance to the saddle slot at the high E string. Then its time for the last glueup on the guitar.

One of the challenges in building a guitar is dealing with curves, and finding a way to hold and clamp the irregular shapes. So, while general woodworking tools can be used for most of the work, some specialty items are a must. For glueing the bridge you MUST have some deep reach clamps like a deep reach C clamps, and (so useful during the entire build) wooden cam clamps. Especially since you are dealing with very thin material, which would be crushed by the usual woodworking clamps. The cam clamps give just enough clamping pressure to do the job. As you can see, there’s not a whole lot of room to maneuver, so doing a dry run first is a given. Once the glue is on, you better be ready.

Now I know what dentists feel like.

Now its just a matter of drilling and tapering the bridge pin holes through the top, filing the slots in the nut, getting the saddle height adjusted, and pickin’ and a grinnin’.

This entry was posted on October 19, 2009 at 3:20 pm and is filed under Acorn House. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.