Incredible the amount of confusion generated by such a simple thing. Given a teeter-totter you guys would figure out a way of explaining it that would go on for years and never get there.
Pivoted arms use a geometry that is cobbled together from a need to compromise several conflicting goals. Try not to confuse and conflate the different goals!
When the stylus is tangent to the groove (null point) the pulling force caused by the friction with be inline with the tonearm’s linear offset, thereby causing a rotational torque around the tonearm’s pivot.
This loopy logic results from confusing the STYLUS being tangent with the line from the stylus to the arm pivot being tangent.
We got a couple things going on. Seriously, keep them straight!
We got a line that runs from the stylus to the pivot. When this line is tangential to the groove then groove drag is perfectly in line and there is no skating force. Period. Does not matter which way you rotate the cartridge, head shell, or any of that. Stylus to pivot perpendicular to groove, zero skating force.
This however is not gonna play music very well! So what we do, make the arm longer. The stylus now overhangs and is beyond tangent. The angle it is off is a vector and that vector force is pushing the arm towards the center. Head shell angle, offset, cartridge alignment DOES NOT MATTER! All that matters
as far as skating force is concerned is the overhang.
Say again,
as far as skating force is concerned! Which, according to the title at the top of the page is the subject we are concerned with here. Skating.
Skating forces have been explained absolutely perfectly by me about a dozen times now. Where people deliberately go confusing is adding in other stuff that we do that does matter
but has nothing to do with skating!The reason for some head shells being cocked off at an angle, or offset, or whatever, cartridge alignment, is all completely different. Now you want to talk about that, fine. But please understand we are no longer talking about skating. We are now talking about tracking angle.
Because the same overhang that introduces skating also puts the arm out of tangency, and this introduces tracking distortion. So we rotate the cartridge trying to get it back at an angle that is tangent.
This is where the cantilever is tangent to the groove. Please note, this is NOT the stylus-pivot being tangent. This is the stylus itself being tangent. We cannot see the stylus, so we use the cantilever as a proxy, and hope the manufacturer has done his job and the stylus is aligned.
Very, very, very important we keep all these thing straight. Each and every one. ALL the confusions above are people conflating, talking about similar but different and sometimes completely unrelated things as if they are all the same. They are not all the same. Get it straight or get it wrong.
I wouldn't mind so much, except playing records is really fun, easy, and sounds great. Until someone comes along with a simple question, and you guys make it seem impossible, and an endless struggle to boot! It is just not that hard. But no one can tell, not from reading stuff like this!
