Uni-Protractor Set tonearm alignment

Dear Mesal, John stated (04-11-11) 'It would be possible to
to design a cam system given different leverages so as better to follow the average variation...' Well this was
the Sony solution as I mentioned before. One get the impression that the issue is rather avoided then solved by
adding more(confusing) variables. But looking to the actual constructions of the antiskate mechanism one can conclude that not much thought is implemented. And those are all mechanical issues that can be measured as well as covered by Newton. Or so I thought.
Regards,
Regards,

Jazzgene
you said

The thing is if the anti-skate force differs from the beginning to the end of an LP, how can a constant weight compensation like the VPI weight on a string work correctly on the entire LP? It can't, I would think.

If your antiskate is the JMW 9 then the force will increase as the arm moves towards the centre if the little arm with the weight is horizontal when the arm reaches the run out. if it is literally a weight on a string, like the old SME, it can aso be set to apply an increasing or reducing force depending on the angle it makes with the arm, though this doesn't apply if the string run round the diameter of the pillar and the radius it is acting at doesn't change.

Check the output wire and make sure it is not counteracting or adding to the antiskate. You can use headphones and a test record to check for distortion on one channel more than the other. If it distorts on the right, you need more antiskate.If the left, less. If it still distorts on the left with no antiskate, the wire is pulling outwards.

Using a greater VTF stops the distortion by nailing the stylus in the groove, but it also increases the skating force because friction is proportional to VTF. If this was not so, our cars would go faster as the braking force increased...

Thuchan

I often sweep things under the mat.... Most people probably do too. Especially the hard things, like precision in areas where it is hard to be accurate or measure reliably - antiskate is one, and, for me, setting cartridge offset is another.

I was playing with an angle protractor this evening and trying to see how repeatably I could measure an angle. Where it was possible to physically set the protractor against both objects it was easy, but by eye maybe within 0.5 degrees.... that is one place we need precision.

Dear Jazzgene, serving as the advocate of mechanics here let me briefly add that skating force does NOT increase with increased VTF.
Why so - since friction is of course direct related to pressure (here: VTF) ?
Because the friction increases on both groove walls - thus the relation of the side-wards pulling skating force to the downforce becomes less ( for those preferring the illustrative real-life picture: the resulting force of "your" sidewards pulling "wife" ( mine rather pulls on the same end of the rope as me .... ) becomes ever less dominant the higher the pressure of your "friend" nailing down the stylus .....).
Not my idea - it's simply mechanics here on our planet under the dreadful influence of gravity.
That's why in general skating force becomes negligible with very high VTF (talk about Ortofon and old SPU's running with 4 - 5 gr. VTF).
If you draw a force vector diagram it will nicely illustrate the point.
The skating force is a product of several sources.
However - the portion which starts it all comes from the breakdown torque of the offset angle.
That's the reason why pivot tonearms with full lateral balance ( direct addressing the static breakdown torque where it originates) and long effective length ( = smaller offset angle ) do display less skating force to start with. Now add higher VTF and the skating force - as a resulting force relative to forces aiming in different directions - becomes less and less with increased VTF.
In contrary this the reason why 9" tonearms working with low VTF and high compliance MMs do of course need anti-skating to address a problem VERY dominant in their particular situation.
Skating force in analog playback is diametral inverse to VTF.
No question about it, - anti-skating is desperately needed with shorter tonearms running with high compliance/low VTF cartridges. Here it resulting side-force is comparatively strong.
Influenced by many parameters all working to add to the skating force.
A longer effective length tonearm with ever smaller offset working with low compliance cartridge and high VTF is the exact opposite situation. Here all corresponding parameters do work to ever lessen the resulting side-force of skating.
BTW - how about starting a "skating - anti-skating"-thread ?
Cheers,
D.

Maybe all said about antiskating. Nevertheless it was quite an exiting expedition and I am still admiring my Ortofon RMA 309 how it manges all these requirements. No I don't need an answer - not this time and not here.

Best & Fun Only - Thuchan