Neck Angle

Before I glue the back on, I decided to check the neck angle. I bolted the neck on such that the neck was flush with the top, clamped the fretboard (no fret wire) on and laid a straight edge on it across to the bridge location. It measured 1/4", although with fret wire it would measure about 18/64". The bridge itself will be 3/8", and this measurement should be 25/64 - 28/64", I am short by 3/32". So my neck angle is insufficient and needs to be adjusted at some point. There is a 3.5:1 lever ratio between the heel and the distance from the 14th to the saddle, so that means I need to remove about 1/32" from the bottom of the heel and taper that surface to increase the neck angle. I'll mess with this during the finishing process.

Tap "tuning" ?!?

I've been tapping around on the top for a week or two since it was glued on and it just seems too stiff both physically and musically. I decided to begin carving the braces down to loosen it up... little by little. I also began to taper the top from the waist down about 3 inches from the edge to the edge. The original top thickness was about 0.120", now the edge is tapered down to between 0.105-0.110".
It is unclear to me which of these did the most good, but the sound and stiffness has definitely changed. Tapping around on the top without the back can be confusing because the sides dampen the sound. So I put it back in the mold WITH the waist spreader bars (that is the most important part. With the mold preventing the sides from vibrating, the tap tones are amazing. It sounds like a deep toned drum, even a moderate amount of sustain.
One other interesting trick is to notice the pitch of a normal tap, and then compare it to the pitch of a tap where you hit it and then leave your finger on the sound board to deaden the vibration. Before the pitches were the same, but now they are different. I forget where I read this, but this is a key to knowing the top is not too tight. Obviously there are a lot of subtleties with tapping; I am very much a beginner and learning every step of the way. But now that the top is starting to sound less "pingy" and more "bonggggy"... it is encouraging.

Top Flush-trimed...

I used the router setup as seen on the last post to flush trim the top. It really wasn't that bad, the bearing bit and side attachment protected the guitar from any "lack of experience/control" on my behalf.
But I realized as I'm doing it that it the plexiglass base that rides on the guitar top isn't correct. Ideally, the router bit will be parallel with the sides... but since the top is domed and the angle varies at different places around the rim, there should be as little contact with the base as possible. In fact, only 2 points on the base (co-linear with router bit) should touch the top. So I re-made the base plate out of wood:
As you can see the sides guide the router around the rim keeping the router bit parallel with the sides at all times, allowing the router base to touch in only a thin strip along the edge such that the angle the top makes doesn't affect the router. Yes this is a bit tricky to control, a balancing act if you will. But it is the correct way to do it. I'll give it a test run to flush trim the back after I glue it on.

Router ready

The last few nights I've been working on my router... to get it ready for flush trimming the sides and ultimately routing the binding/purfling channels. First, I removed the plexiglass plate that came with the router and added a bigger version that extends 2" further than the original. But I didn't just slap it on, I shimmed it by a washer to give a slight angle. This angle varies from 90.9º to 91.6º, and is to compensate for the fact that the top and back are slightly domed... 30' on the top, 15' on the back. The washer I used was 0.040" thick, but perfect compensation would be 0.030" at the top/bottom and 0.080" at the waist... splitting the difference is probably good enough.
This router came with a side attachment, but wouldn't work with my 3/4" flush trim (negative shear angle) bit from CMT. So I added a wooden piece to it (as seen in photo) even though I probably don't need to since I'm using a bearing bit... it gives more room for error. This arrangement should also work with the 1" rabbiting bit I'll use with the bindings/purflings since it is somewhat adjustable. I'll probably wait to do the flush trim until after the back is on... until then I'll just practice on some scrap a few times.

One small step...

Last night I took the plunge...and glued the top to the sides. Believe me, there was some trepidation... but in the end it went well. This morning I took all the clamps off and it appears to be a good joint. You can see the wax paper on the neck tenon that I used to keep from gluing the neck to the top/sides during this process.

Deflection Tests

Before I glue on the top, I wanted to do some quick deflection tests. I performed two different tests, both with a 2.5 lb weight... measuring the deflection in the middle.
Test #1 was supported at the top and bottom, it yielded 0.085" deflection.
Test #2 was supported at the upper & lower bouts, it yielded 0.065" deflection.
Ultimately, I should be able to come up with a stiffness number... similar to the Moment of Inertia. Then compare this to subsequent guitars I build.