But viscosity is about shear forces, so an aerofoil shape still has to shear the liquid between its moving surface and stationary liquid further away. Indeed, there are many ways to implement unipivot damping, but the traditional solution was an annulus that didn't so much slice the liquid as try to slop it from side to side. I don't see that such an arrangement will provide a linear damping force.
I would have thought that a linear tracker would require rather different vertical and lateral damping simply because vertical effective mass tends to be low but lateral mass very high. Or perhaps you mean that you aim to make the Q equal in both directions?
Oh, and you're right about engine oil. Horrible stuff to clear up. But so is silicone fluid. Goes with the territory.
I would have thought that a linear tracker would require rather different vertical and lateral damping simply because vertical effective mass tends to be low but lateral mass very high. Or perhaps you mean that you aim to make the Q equal in both directions?
Oh, and you're right about engine oil. Horrible stuff to clear up. But so is silicone fluid. Goes with the territory.
Probably a thin paddle which can be rotated on vertical axis and lowered or can be lifted be an ideal solution ? since tonearm balances on just two points one of which is dynamic why is lateral balance not important ? Most unipivots have low hanging mass as counterweight which exerts inertia and due to offset angled headshell and cartridge lateral balance is uneven. If there is any implemention on countering these can anyone point me to link or discussion ?
Thanks and regards.
Thanks and regards.
Yes, a thin paddle with screw-adjustable depth might work very nicely. Lateral balance is crucial for a unipivot, sometimes set by rotating an eccentric counterweight but more conveniently by a separate lateral weight. The fact that the cartridge is angled at the headshell is irrelevant. What is important is that the stylus tip should be on the centre line of the arm tube. Provided that is true, and the arm is in lateral balance, the centre of inertia is very nearly also on the centre line of the arm tube and the arm will not twist as it traverses a warp because the stylus applies the vertical force at a neutral point. (Very nearly, because the mass of the cartridge is unavoidably not centred on the arm tube and its offset inertia is unlikely to be equal to the offset inertia of the lateral balance weight that balances it.) If pivot height is at record height, this makes it even more difficult for up and down motion to cause twist.
My linear arms have almost identical vertical and lateral resonant frequencies, so their effective masses are the same or at least they are similar.