More Shimming

I spent some time compulsively measuring the thickness of everything credit-card like thing I could find around the house.  In the end I decided to

• Lower the saddles so that the height was correct.  The height at the nut was 0.051 inches, and the body to neck height in the middle of the diagram was 0.0343, so the saddle height should be 0.394, which is just a little under 25/64. I used my Stewart MacDonald String Action Gauge to adjust the height of the low E string first
• I cut a shim from my old NYHRC card.  This card is 0.75mm, substantially larger than the Metrocard, but still not quite as thick as a credit card.

Interestingly I once again had to loosen the truss rod to add some relief and, even having done that, I've got something like 0.006, which is rather low compared to the Fender spec.

Wow that's an irritating animated GIF.  If anyone other than I read this blog I'd have to remove it.  With this shim in place, the guitar seems a lot better.  The saddles are lower. It does bug me to have that gap between the neck and the pocket.  I'd be happier with a tapered piece of plastic that has screwholes and fits across the top of the neck fully.  Maybe I'll try to do that next.

An Interesting Observation

With the shim, and lower saddles, and the guitar tuned up, I find my trem is decked! This means the string tension is undoubtedly lower.  I don't get that.  I would have thought that a certain fixed amount of tension would be required to get a particular string to a particular note and that's it.  It must be more subtle than that.  With lower posts, various angles are different, and so some physical quantities must be different. Torque or something like that?  This is just the kind of lesson I was hoping to learn from doing this project.   Even if there's a paragraph in some Erlewine book that says the same thing, it becomes real only through having observed it "in the wild".  

To Float Or Not To Float

Should I loosen the springs now?  I have no float at all. It would seem stupid to have the Tremel No in there and not have some float. I wish I knew enough physics to understand this a bit better - or at least had better intuition about this kind of stuff.  Loosening the springs will decrease tension "exerted" by them.  The guitar will go out of tune (flat) and the bridge will float up a bit.  Then I'll tune it and the bridge will float less due the increased tension from the strings being tighter.  Or something like that.  

I've seen derisive comments about statements like "string tension should equal spring tension".   It seems those deriders are saying that the correct thing to say is "torque from the strings should equal torque from the springs". I can't say because I don't know what it means, unlol.