The bridge is pretty much bottomed out, means you can't lower it anymore. Which is a sign that the neck angle is too shallow. You see that there is almost no break angle over the bridge.
Here is an example for a "good" break angle, but that is almost impossible on a Starfire with bigsby. It's just to illustrate what we say.
Setting up an electric guitar follows the same rules like for an acoustic guitar. At that point you don't even worry about pickups!
So first you make sure the neck is "straight". You would correct if necessary with the truss rod nut.
Stick a
capo on the first fret, press down on the 15th fret and then use the straight string as a guide to see how bent forward the neck is. The feeler gauge is put over the eighth or ninth fret underneath the string - .007” is the magic clearance, which is like a thin business card or two sheets of paper. Any smaller than that clearance and the string will bang onto the frets when played; much larger than that and the string’s height will be excessive.
When turning the truss rod nut, do never turn it more than 1/8th of a turn before tuning the guitar again and measuring again. Step by step.
Next step would be to adjust the height of the bridge by turning the thumbwheels on the bridgebase. In your case there might be no possibility to adjust anything as the bridge is already at the bottom, but let me explain:
"Typically" an acoustic guitar is setup to 6/64th at the low E and 4/64th at the high E-string at the 12th fret.
A good place to start for the action of an electric guitar is at the 12th fret (with no capo on) 5/64th" or 4/64″ on the low E string and 4/64th or 3/64″ on the high E.
Mind that all depends on the players preferences. A hard strummer or a bluegrass picker might like the action relatively high, in order to avoid string-buzzing. Many jazz guitarists prefer low action, which is friendlier to fingers playing fast scale runs and numerous, rapid, frequently complex chord changes. Lower action is more likely to produce string-buzzing.
So the below would be o.k. for many, or a little bit too high for some. Depends also what string gauge you use and how hard you bend strings:
With your action set and test played for buzzing, it’s time to look at the pickups and adjust them in height, maybe angle and adjust the polepieces. But honestly, Dirk Wacker here explains that much better than I can do:
What’s the ideal pickup height? And how do you adjust the pole pieces?
www.premierguitar.com
As a last and important step you need to set the intonation! It means you need to set the correct length of the strings, so when you press a string on a fret it is in tune.
Normally you change the tone of a string by turning the tuning machine, so you set for instance the length of the D string to a tone D. But that is only fine as long as you don't press any frets when playing. So what means intonation? What you want to achive is that the harmonic chimed on the twelfth fret (means string is straight and you just touch it very slightly above the 12th fret without actually pressing it down) is in tune with the note played on the twelfth fret (means string pressed on the 12th fret). In that case both the string and the fretted string at the 12th fret are in tune, so the guitar sounds perfect when fretting.
You can imagine that by shifting the entire bridge back and forth you would change the length from the 12th fret to the saddle vs. the fixed length from the nut to the 12th fret. Depending on string thickness that is a bit different, hence you see saddles are not exactly in a 90deg angle with the strings but are slightly diagonal. (hence also two different intonated fixed bridges for a would or unwound G string, but that is yet another topic).
You normally need to set intonation one by one for each of the 6 strings. On an adjustable bridge it means moving the 6 saddle pieces back or forth, but in your case you can only move the whole floating bridge to set only the low and high E strings. So less work for you. I think I also posted videos before how to set the intonation with an archtop bridge. YouTube has many good examples.
By the way, the bridge in your first pictures in post #1 above looks like it is not at the perfect position. The strings might be not correctly intonated.
This picture below shows how you would move the 6 saddle pieces, if you would have such a bridge.
A floating bridge can only be placed in one place on any given guitar, but that place is unique to each guitar: it has to be set so that the harmonic chimed on the twelfth fret is in tune with the note played on the twelfth fret. (Of course, it is roughly the same place on all given guitars of a certain model, but each guitar has a unique sweet spot where the harmonics and notes at the twelfth fret match just right. Also, it is a given that the bridge must be someplace where the strings run straight in line with the neck of the guitar; don't move the bridge accidently too far to the left or right.)
To do this, place the bridge about where you think it needs to go. On some old guitars there is a lot of scuffing and minor scratching in the area where it used to be. Once the guitar is in tune, check the note and the harmonic at the twelfth fret. On your bridge you only do the first and sixth strings. You will need to loosen the strings in order to move the bridge, and only move it a little bit at a time if the harmonic and the note are close. Then tighten up the string or strings on the side of the bridge you are adjusting and check the harmonic and note at the twelfth fret again. And after each step check the tuning again.
Use an electronic tuner that shows flat or sharp and can pick up the harmonics as well.
If the note is sharper (higher in pitch) than the harmonic, move the bridge down toward the tailpiece. If the note is flatter (lower in pitch) than the harmonic, move the bridge up toward the neck of the guitar. When you move the bridge, move it one side at a time, and work on getting either the sixth or the first string set first. When I say move the bridge, I am talking about moving it a sixteenth of an inch or so at a time. This is a time-consuming process so you need to give yourself a long time and a lot of breaks the first time you try this. It can be very frustrating at first, but as your ear develops, it gets a lot easier.
Oh, and of course, changing the height of the bridge will also affect intonation. If you lower the action of the strings, you may find that you need to re-do your intonation. You also will need to re-do intonation if you switch from light to medium strings and vice versa. All in all, if you can't get your guitar to sound properly in tune, the bridge probably is misaligned.
Nuuska pointed out, that intonation is also slightly affected also by pickup height, so in case you would change the pickup height or the pickup polepieces height you should again check the intonation, means you need to shift the bridge maybe a tiny bit again. Reason is that the magnets of some pickups pull the strings towards the pickup, the more the closer they are, so the string would sound a tiny bit out of tune. Hence moving the bridge very slightly would compensate for that effect. In
post #19 Walter points out that this is not a general rule however.
In any case, afterwards mark the bridge position somehow so that you have a faster process next time you change strings or you clean the guitar. If it is not a brand new guitar you could use a needle and scratch very lightly the top at the 4 corners only (just like a few dots), so that it doesn't damage the lacquer but still you can see the scratch with a light.
Maybe one more tip: Before changing strings on a guitar with a floating bridge it is always a good idea before you remove any strings to mark the position with some (low stick) tape like in this picture:
Ralf
