Lewn Theoretically you are correct in that varying tangency will change the force vector but in real life the error is so small it does not account for much.
You are mistaking velocity with record speed. As the modulation increases so does velocity. In a heavily modulated groove the record has to exert more force on the stylus to move it and the stylus is moving faster. In a straight groove the record is applying only straight ahead friction and the stylus is not moving (through space) at all. The energy (work) required to move the stylus is seen as friction and a little heat. You could make the argument that anti skate does not decrease towards the center of the record because actual velocity does not change. There are just as many squiggles they are just closer together. And indeed it does not change as much as you would expect given the vast difference in groove speed between the outside and inside of the record. I did make a miss statement earlier when I said velocity decreased towards the inside of the record. It does not. Groove speed decreases towards the inside of the record. What would be nice is a test record with a bias band an entire side. That would be fun!
You are mistaking velocity with record speed. As the modulation increases so does velocity. In a heavily modulated groove the record has to exert more force on the stylus to move it and the stylus is moving faster. In a straight groove the record is applying only straight ahead friction and the stylus is not moving (through space) at all. The energy (work) required to move the stylus is seen as friction and a little heat. You could make the argument that anti skate does not decrease towards the center of the record because actual velocity does not change. There are just as many squiggles they are just closer together. And indeed it does not change as much as you would expect given the vast difference in groove speed between the outside and inside of the record. I did make a miss statement earlier when I said velocity decreased towards the inside of the record. It does not. Groove speed decreases towards the inside of the record. What would be nice is a test record with a bias band an entire side. That would be fun!