I did a bunch of prep work and cut ramps in the head stock slots. I made squared off ones for the first time. A little scary I just cut the edges with a razor saw and carved out the waste with a chisel. There is a bit of back and forth to get the line between the veneer and mahogany to look symmetrical.
March 10th 2015
I am waiting a few more days until the finish cures of the guitar so that I can buff it out. While waiting I decided to build a contemporary bridge mostly following the instructions from Gore\Gilet build volume. This is a CF, 2 layers, reinforced Padauk. I used padauk as it is lighter than rosewood by a little bit. A lot lighter than cocobolo. It is a little heavier than black walnut, but at least as the time I wanted the color.
Before making the bridge I made a router jig to route the separation between the saddle block and the tie block. Also I used it to route a saddle. The jig is simple I routed a channel for two pieces of aluminium that were just right two hold the router base guide stable. With the tracks in place I used the router in the guides to route a well for to hold the bridge while I am working on it. The leading edge of the well is perfectly in line with the router track because I routed it using the track.
I sliced a strip of padauk close to the bridge size and resawed it so that I could make a 2 mm, 3 mm and a 4 mm slices to be laminated with the carbon fiber strips.
I used some west system epoxy 105\206, laminated the stack together, clamped it and let it cure overnight
The next step was drilling the string holes. I tried to make I nice reusable jig out of wood and aluminium, but drilled one hole off center. So I just drilled the holes in the bridge on my drill press. I took a bunch of extra time to make sure that everything was square to the drill bit.
I used my jig to make the first cut to separate the tie block and the saddle block. This cut went to 2mm from the bottom of the bridge. I then shaped the saddle with my luthiers friend remounted the bridge in my jig and cut the saddle and cut ledges for some bone strips on the tie block. I shaped the saddle block a bit with chisels and sand paper.
The bridge ended up at 16.5 grams (minus the bone that is coming)
I am still nervous about the color, as it is different for a bridge. But with a hint of brown in shellac it is not horribly off of the cocobolo head plate.
March 12th 2015
Yikes, when I installed the tuners in the middle of the head stock on one side the tuner was up above the veneer about a half of mm. I remember how proud I was of my ability to sharpen a scrapper while thicknessing the veneer to the final thickness. It appears on one side I scooped out a bit much. I thought for a bit of leaving it, but finally I got the nerve and lay my iron on to the top of the the head stock. cleanly pealed off the veneer and glued and shaped a new one. This time I put black fiber between the head stock and the veneer.
March 14th 2015
This is not the jig that Trevor Gore uses to machine his compensated nuts. He has a much more elegant jig that allows him to adjust the compensation he needs for each string attach a sized nut blank to the jig and machine the nut using a drill press as a pin router. I could not get together everything I needed to make the jig so until I do I found another method using my new made classical bridge jig that I based off of one in the book It seems to work.
When I made the classical bridge jig I used the rails to make the well so the front edge is parallel to the rails. My bishop Cochran router base adjustment is .8 mm per turn. So 1/2 = .4 mm, 1/4 = .2 and 1/8 = .1. These are all positions that are easy to see. I could probably get close to .05.
I made a nut holder that was the same thickness as the fret board so that I could easily set the depth. I zeroed on the front of the nut and proceeded to cut each slot. I had one that string location that I needed to ease the router into the rails. But it came out ok and pretty accurate. I have them all a tad more compensated so that I can clean the leading edge.
It still needs shaping but the front ledges are very close to where they should be. I will do a bit of clean up and make them just tight.
I glued the bone into the bridge so it was time to glue the bridge down.
I level sanded and polished the guitar so that I could do that without the bridge in the way. I used my ROS at 600 grit light sanding and then micro mesh disks up to 8000, followed by buffing.
Because I am doing all of this fancy compensation, I check and double checked the bridge placement. I used the 12 fret as my home to measure from as the nut edge of the fret board was cut 2 mm shorter. Because I have a compensated nut I need only .8 mm of compensation. I do have a wide saddle for a classical so I can compensated up to 3 mm.
I checked the plans to find a good location for the locating pins and drilled them
I use a scalpel with a brand new blade to outline the bridge. It is so sharp that a light cut cleanly cuts through the finish.
I use a heavy duty utility blade to scrape the finish off the wood. I tape the back end so I only need to keep track of one end.
To get ready for the vacuum clamp I taped some appropriate sized blocks on the wings, I just find it does a better job of clamping the wings, I leave the pins end but I duck taped the slot to get rid of leaks. I applied the vacuum clamp for about 8 minutes, cleaned up the squeeze out and am keeping it clamped for an hour or two.
March 14th 2015
and the tap test ...
With the bridge glued on I did a tap test of this falcate classical. I think it came out with working values. Depending what happens with the strings, I can add mass to the sides if I want to lower the top off F# (I know it is right on F# as I have my falcate SS guitar on the wall with the g string tuned down to F# and it started singing. I left the bottom brace pretty tall so I can get the back on target as well. I will wait for the strings first. From a closed box tap test the top came down two hertz with the bridge and air up about 2 Hz. My fret board covers a bit of the sound hole so that might be what changed the air resonance.
March 22nd 2015
I completed my first falcate classical. All and all the project came out OK and the guitar sounds good, but I did miss my target frequency on the top. As seen in the figure below I was low around 178 Hz instead of 190 Hz for the top. This lower frequency puts the top and the Air resonance an octave apart 88.6 Hz. I am not really hearing any horrible weakness around F but I am also not hearing what the guitar could have sounded like. I did put the back about 4 semitones away at 224 Hz. Ultimately I should have had the falcate braces taller. Possible the 7 mm that I used for my SS.
As part of a postmortem on the project I looked back at my design assumptions. I noted that my falcate SS top was 172 Hz not the 180 I used in the assumptions for my relative analysts. If I was a bit more careful early on and knowing that I wanted to push the target top resonance 20 Hz higher than my SS I may have left the braces taller.
Over all I am still happy with what I have and I have good data for my next attempt and a good guitar.