"When used to check certain soft materials like Aluminium, Cast Iron, ruby balls tend to accumulate small bits on their surface, rapidly leading to errors in measurements. When used in scanning applications, ruby balls are susceptible to wear, particularly on abrasive surfaces. Silicon Nitride Balls exhibits no tendency to accumulate material and better abrasive resistance. Scanning CMM users report up to 5 times longer tool life with Silicon Nitride Balls than ruby balls." Mr. Tom Breth, Q-Mark CMM Accessories.It seems that actual hardness is not the major issue here but the properties of the materials vis performance over time.
Silicon Nitride vs Ruby bearing for Rega P5
I upgraded my P5 last year with a groovetracer subplatter and ruby bearing for an improvement my wife called "shocking". I've now come across the silicon nitride bearing and have one in hand. I'm reluctant to turn the TT upside down, swab out the well, etc. if the change of bearing isn't going to provide audible improvement. Anyone try this before? Will appreciate your thoughts.........