Revisiting some of the posts!!
Klaus R. wrote:2. Flom, The deformation of plastics with hard, spherical indenters, J. of Audio Eng. Soc. 1959, p.122
Plastic deformation on vinyl occurs for a 0.005 cm stylus at 5 grams static
0.005cm = 5 um (micrometers) =0.2 mil, far far smaller than the typical 18uM=0.7mil conical stylus, which is specified to be used at 5g or less.
0.2 mil -> 5g
Klaus R. wrote:3. Walton, Gramophone record deformation, Wireless World 1961, July, p.353
Shows a graph with VTF vs stylus radius : plastic deformation is caused for spherical styli of 0.0003 inch at 2.1 gr deformation, 0.0004 inch 2.7 gr, 0.0005 inch 3.1 gr etc.
Converting to mils:
0.3mil -> 2.1gr
0.4mil -> 2.7gr
0.5mil -> 3.1gr (now this is an available size for conicals)
Klaus R. wrote:A first play at 9 grams had worn off 1.5 dB. For the same standard M3D cartridge at 9 gr a drop of 5 dB at 15 kHz occured, at 6 gr 2 dB, at 3 gr no drop , all drops indicated after 20 plays
Fortunately no one needs 9gr VTF these days!
Klaus R. wrote:5. Oakley, Inner groove distortion, Audio Magazine 1962, June, p.57
For 0.5 mil styli a VTF of more than 3 grams tends to erase high frequencies
More or less exactly what Walton (3) reported.
Klaus R. wrote:7. Walton, Stylus mass and reproduction distortion, Wireless World 1963, April p.171
Pictures of stereo grooves played with pickup at 2.7 gr VTF (stylus mass 3
mg). Permanent indent depth = half modulation depth. After 5 playings, little further deformation is visible. Low effective tip mass is advantageous.
My comment: Practically all good styli today are 1mg effective stylus mass or less.
Klaus R. wrote:8. Kogen, The elliptical stylus, Audio Magazine 1964, May, p.33
0.7 mil circular tip
slight change between 10-20 Khz at 3 gr after 100 plays
Sounds coherent with the other tests.