Tonearms without anti-skate, damage to records?

@dover I prefer weight on a string 

Can you explain how you determine the 25 - 30% via this method?

unfortunately, not true for straight line trackers because of the very high horizontal effective mass. The stylus and cantilever have to drag this along and even with an air bearing you can observe the cantilever deflecting and if level is not dead on it can be a real battle. 

@mijostyn 

Whilst I agree with high horizontal mass being not ideal, in reality the lateral forces on the cantilever are still lower than a pivoted arm - this is documented on the Eminent Technology website.

In fact here is an explanation from Bruce Thigpen himself

The untold parameter of a pivoted tonearm: To minimize tracking
error, pivoted tonearms were lengthened with a bend in the wand, or by
mounting the stylus at an angle in the headshell. The frictional force
of the stylus in the groove wants to straighten out the bend or crawl up
the records inner groove wall. When using anti skating with a pivoted
tonearm to prevent inner groove wear, regardless of mass, pivoted
tonearms bend the stylus with an opposite side load force of between .1
and .2 grams per gram of tracking force, the tonearm shaft is being
twisted outward (as viewed from above) with this static load which goes
through the stylus suspension, but the percentage of creep on the inner
wall of the record groove actually varies with the passage loudness or %
groove modulation. So you are constantly bending the stylus while only
marginally solving the problem.

With the ET-2 the side loads to accelerate the tonearm at .55hz
(33/13 RPM) are less than half of those values for an eccentricity of
.0312 inches (1/32 inch) and are a linear function of record
eccentricity. The cartridge cantilever suspension sees much lower loads.

So as you add mass, this side load value of the ET-2 goes up
linearly, but is always less than using any pivoted tonearm with anti
skating.

As an example I ran a high compliance Shure V15vmr ( with stabiliser removed ) in the ET2 for 10 years without changing the stylus. The cantilever was still dead straight after 10 years. The only significant mod I did to the ET2 was to run magnetic damping for the horizontal movement using eddy currents.

@mijostyn ​​@dover 

Re parallel trackers, look at the Simon Yorke Aeroarm (no longer available).

Effective mass of the arm is around 25% of a typical 9 inch pivoted arm because it is only 2.5 inches long.  Why do most other designers of parallel trackers keep the length near 9 inches just because most pivoted arms are 9 inches?

I have closely observed the cantilever of 6 high-end cartridges mounted on my Aeroarm and there is no sideways torsion whatsoever.  Tracking is totally secure at the low end of most manufacturers' recommendations.  van den Huls track securely at 1.6g.  Lightweight Ortofons like A90 and A95 are a match made in heaven with Aeroarm.  I will never go back to pivoted arms.

@dover   Please explain why you think the skating force does not change linearly as the record is played.  Surely it is just a question of geometry?

@rsf507

@dover I prefer weight on a string 

Can you explain how you determine the 25 - 30% via this method?

Yes - you can use scales to measure the actual falling weight, it won't be exact because there will be some loss due to the mechanism ( usually friction ). However it is more accurate than most sprung or magnetic antiskate mechanisms.

2 examples - 

FR64S - this has markings on a pivoted rod that you slide the weight along that denote 0.5g increments in antiskate.  I actually measured using strain gauge scales the falling weight at each increment and was surprised to find the markings very accurate. Measuring the falling weight ( with the platter removed ) at various points across the record showed very little if any deviation as the rod went off horizontal.

With this arm I set the arm up such that the rod that the weight sits on is horizontal at the mid point of the record ( to minimise deviation ) - seems to work well.

Kuzma 4point - recently installed a van den hul Grand Cru with a specified antiskate force recommended by van den hul of around 0.2g - the only way I could achieve a level this low was to use a piece of bluetack carefully trimmed and measured on stylus scales instead of the metal weight - even Franc's custom small weight could not get this low. 

@dover   Please explain why you think the skating force does not change linearly as the record is played.  Surely it is just a question of geometry?

I never said that.

On a linear tracking arm there is no skating force.

On a pivoted arm it varies across the record.