If you are adjusting a Fender Strat-style guitar with a floating bridge, this is the point at which you will balance the trem so that the strings will pull the bridge base off of the body. Floating Strat bridges do have tuning and stability issues, but if they are of good quality and adjusted correctly they can sound great. When you float the bridge, you are essentially putting the trem springs in the mix. There is definitely a tone in that. Plus, the ability to pull back on the arm is a beautiful thing when doing light vibrato.
Adjusting a floating trem
To adjust a floating trem, you will essentially copy the steps of the hardtail bridge up until the last step. I would recommend either adding a removable wedge-shaped block behind the trem block or tightening the spring claw behind the guitar. This is so the trem doesn’t move when going through the steps of tuning and adjusting saddles. Then tune again. If you block the trem or tighten the claw, you will essentially turn the guitar into a hardtail until you start to balance the trem. There are two styles of floating Strat bridges: six-screw or blade-style.
For a six-screw design:
If your guitar has a six-screw design, you should tighten the two screws that attach the bridge base to the body so they make equal contact on the bridge base plate, then lift the four in the center so they are lifted up off of the base equally. This will allow for those two outer screws to hold the base plate down while the four in the middle act as support but don’t impede movement of the trem.
For a blade-style bridge:
If your guitar has a blade-style bridge base plate that only has two outer screws below the E strings, you will raise these up so the entire base plate will lift off of the body when the block is removed. After adjusting the saddles, you can either remove the trem block or start to release the two spring claw screws. This allows the strings to pull the block forward and float. For this type of bridge, the front edge of the bridge should make contact with the top of the body while the back edge (under the saddle intonation screws) is lifted off of the body about 1/16”. You will need to go back and forth re-tuning the guitar and either letting out the spring claw or tightening it until the bridge base plate is floating correctly.
On a blade-style bridge base plate, you will go through the process of re-tuning. Either tighten or release the spring claw until the entire base plate is floating off of the body parallel to the top. After the bridge is floating properly, you will probably notice that the string action has raised slightly. The back edge of the bridge comes up, and the strings pull the bridge off of the body.
Tune the guitar
At this point, you will want to make sure that the guitar is in tune. Place a capo on the first fret. Then go through the process of adjusting the saddles with the bass side at 5/64” and treble at 4/64”. Then lower the middle four strings using the under-saddle radius gauge as your guide. After making these adjustments, you can put the guitar back up to pitch. The trem should properly float at that action height.