The skating force that acts on a stylus to cause the arm to swing towards the spindle is generated by the friction between stylus and record. It acts along an axis which is tangent to the curve at the point where the stylus meets the record.
If there is no groove, then that simply means the amount and nature of the friction force is different depending on the stylus profile and how much, or how little, it digs into the blank record surface.
In other words the stylus will skate if there is VTF and the arm has overhang, unless something stops it.
The point to remember is that the stylus is stopped from skating by the inner groove face, not constrained by the outer.
When playing an LP, with enough VTF the stylus will stay in the groove, but there will still be unequal downforce on each channel. With anti-skate applied, these forces can be equalised. That's the way it is.
There is always a skating force.
If there is no groove, then that simply means the amount and nature of the friction force is different depending on the stylus profile and how much, or how little, it digs into the blank record surface.
In other words the stylus will skate if there is VTF and the arm has overhang, unless something stops it.
The point to remember is that the stylus is stopped from skating by the inner groove face, not constrained by the outer.
When playing an LP, with enough VTF the stylus will stay in the groove, but there will still be unequal downforce on each channel. With anti-skate applied, these forces can be equalised. That's the way it is.
There is always a skating force.
Depending on arm length and stylus, it will usually be from 10 to 30 % of VTF. The force varies across the record, so it might change from say 20 to 30 % of VTF from outer to inner groove in the case of a 9" arm.
If, with particular set ups, users prefer not to use anti-skate, then they presumably feel the trade-off is worth it.
This doesn't mean there is no skating force.
The centripetal (seeking the centre) force In terms of the arm, which is the rotating part in this context, not the cartridge, would be that acting from stylus to arm pivot in reaction to its opposite component which is supplied by the friction on the stylus. The remaining component of that friction force acts to rotate the arm, and is the skating force we all know and love...
(In normal usage, the "centripetal" force is described by the force preventing the arm from moving away from the centre, i.e. acting towards the centre, as in the case of an object being spun on the end of a string, where there are no additional forces acting on the object. The centripetal component of this nature due to the rotational velocity of the arm and cartridge in a tonearm is, of course, virtually zero.)
