Acoustic Guitar Construction

I used royal-lac shellac to finish the back and sides and neck and I did a true french polish shellac finish on the top. I have not yet done any sanding or buffing but it looks pretty good now. I am going to let the guitar sit a week to allow the shellac to cure a bit.



Before finishing the top I looked for glue on the top with a black light. Yup I had some smears in the center and some along the bindings. You can see the bright spot in the lower bout especially along the edges. This is after I though I had the top clean.

Beautiful John

I'm learning something here. The photo of the guitar top under black light, and the illumination of glue spots...howzat work? Were the glue spots visible under normal light or feel-able when fingers scanned the soundboard?

Thanks!

The LMI yellow glue is made to fluoresce under a black light. But I have found that many things show up under a black light not apparent to seeing them in normal light. The smudge in the treble side in the center of the lower bout was not visible in normal light. Even knowing it was there I could not see it in normal light. I might have found it wetting down the top before knocking down the grain and sealing. I thought this top was clean and ready for sanding. I started this check because two days into spraying my last guitar I notice light reflecting funny off of a glue smudge on the top. Under finish I needed to hit the light at the right angle to see the reflection, everything looked great while spraying. With the right angle it flashed like reflective bicycle gear, or so it seemed at time.

Learn something every day. Thanks.

I made one of two possible bridges Gore style bridges for this instrument. The first one I made is made out of Brazilian rosewood, the second will be made out of walnut and ebonised. I think the walnut will be a lighter bridge. they both are reinforced with two separated layers of CF fabric. I used a very dark block of BRZ.

In the first set of photos you can see me ready to put the block together. I resawed the bridge blank I had into three strips 2mm, 3mm and 4 mm. These are put together such that the 2 mm is on top and 4 mm is on the bottom. The carbon fiber fabric will be separated by the middle 3 mm slice. As shown in the picture I used west system 105\206 epoxy for the lamination.







While waiting for the epoxy to cure I found some interesting mushrooms in my yard. These might cause a bit of delay. :)



I had a previous walnut layup that I made when I made my last falcate classical guitar. They sort of look a mess until they are trimmed to size.



I marked out the tie holes on the blank and drilled them in the drill press. I attempted to make a nice aluminium jig for the tie holes but had trouble drilling the holes the twist bits I had did not cut it in the aluminium. I did not use the cross vice as a cross vice. I had punched the holes and just moved the vice in place for each hole.



I mounted the blank (actually the second attempt) in my routing jig. In the first attempt I relied only on double stick tape and it did not stick. I cut that spoiled bridge diagonally and made the wedges that you can see in the photo.



I do four passes in this jig. The first pass with a bull nose 1/8" veining bit is to separate the tie and saddle block. This is done to the depth of the wings. I switch to a straight edged 1/8" bit and create 1.5 mm x 1.5 mm rebates on the tie block for bone strips. The last uses the same bit to cut the saddle slot. The Gore\Gilet book describes on additional cut with a 45 degree bevel bit to slope the inside channel toward the saddle. I do this with a chisel. I used a Luthier Friend jig do shape the wings.













Here it is just needing a bit of finish sanding.

I finished applying shellac last week. To position the bridge I bolted on the neck. A perfect time for some encouraging photos. I still have yet to level sand or polish the royal-lac back and sides or the French Polished top. It looks good in the pictures, but it definitely has a hand applied finish look.







I set the fret board nut location to have a nut compensation as well as saddle compensation. I really spent a lot of time calculating and triple checking the location of the saddle. I did all of the measurements from the first slot as the fret board is about 3 mm short of the zero slot location. After it was taped in place I also checked the location against my other falcate classical (I could have thought about this first) and I had located it exactly in the same location.



I drilled a couple of 1/16" holes in the saddle slot and used the drill bits as location pins.



With the bridge in place using a new scalpel blade I carefully scored the finish and used a utility blade (actually three by the time I finished) to scrape the shellac under the bride.







I glued the bridge in place. Added a couple of shims to the wings to help push them down and fired up my vacuum clamp to clamp the bridge. After about 6 minutes I stop the clamping and removed the still soft squeeze-out. It has been clamping for about an hour now so I can head back down.