Craig B
Re:trophile
Sorry Stan, I've no photos to share, however, I do have a couple of dodecahedron balls, from customers who couldn't help themselves from removing and replacing their spindles, that I could send to you upon receipt of a postage paid envelope.
To be honest, I was exaggerating with the boring through bit, but only slightly so if one were able to compress time. The rationale being that, with a none-captive single ball turntable bearing, there exists 4 bearing surfaces: 1) the flat end of the hardened steel spindle; 2) the top contact patch of the stationary equally hard ball; 3) the bottom contact patch of the ball; and 4) the bottom thrust plate (or pad) of the bearing well.
With Rega's hardened steel spindle, similar hardness ball, and sintered bronze bearing well, the 'softest' material is the bottom of the well. The softer bottom bearing surface of the well isn't a problem in practice, as once the ball has centered itself it will remain stationary as the spindle rotates about its axis on the top contact patch of the ball (aka the first point of least resistance); this will go on for years unless the ball is disturbed by lifting the spindle, clean/re-lube, etc., in which case, the same spindle contact patch mates with a new contact patch on the ball. This is easily observed when removing a Rega hub/bearing assembly for its recommended initial 10 year oil change (used to be 20 years) as the flat bottom end of the spindle will exhibit a perfectly centred small dimple, whereas, the bottom of the bearing well will generally exhibit little more than a dark dot of discolouration (assuming the bearing hasn't lost oil since new due to the spindle having being disturbed beyond a lift of 2cm for visual check, deck left upside down for more than 20 minutes, all out bearing removal, etc.).
Should enough time pass that a given ball bearing eventually wears a deep enough depression in the spindle end, it will effectively become a captive ball bearing, in which case it will rotate equally with the spindle and wear against the bottom of the bearing well (aka the new first point of least resistance). My point being (and presumably YNWOAN's above) is that the hardness mismatch between tool steel and ceramic will see the spindle end dimple enlarge much more rapidly. Should that enlargement eventually 'capture' the ball then the relatively much softer bearing well bottom has no chance.
Looking on the bright side, unless the bearing goes totally dry, none of us are likely to live long enough to hear the ball drop.
P.S. With captive ball bearings, or spherical spindle ends like that of Linn (and others before Linn, despite the patent grant), the bearing well typically has an equally hard polished thrust plate fitted.
To be honest, I was exaggerating with the boring through bit, but only slightly so if one were able to compress time. The rationale being that, with a none-captive single ball turntable bearing, there exists 4 bearing surfaces: 1) the flat end of the hardened steel spindle; 2) the top contact patch of the stationary equally hard ball; 3) the bottom contact patch of the ball; and 4) the bottom thrust plate (or pad) of the bearing well.
With Rega's hardened steel spindle, similar hardness ball, and sintered bronze bearing well, the 'softest' material is the bottom of the well. The softer bottom bearing surface of the well isn't a problem in practice, as once the ball has centered itself it will remain stationary as the spindle rotates about its axis on the top contact patch of the ball (aka the first point of least resistance); this will go on for years unless the ball is disturbed by lifting the spindle, clean/re-lube, etc., in which case, the same spindle contact patch mates with a new contact patch on the ball. This is easily observed when removing a Rega hub/bearing assembly for its recommended initial 10 year oil change (used to be 20 years) as the flat bottom end of the spindle will exhibit a perfectly centred small dimple, whereas, the bottom of the bearing well will generally exhibit little more than a dark dot of discolouration (assuming the bearing hasn't lost oil since new due to the spindle having being disturbed beyond a lift of 2cm for visual check, deck left upside down for more than 20 minutes, all out bearing removal, etc.).
Should enough time pass that a given ball bearing eventually wears a deep enough depression in the spindle end, it will effectively become a captive ball bearing, in which case it will rotate equally with the spindle and wear against the bottom of the bearing well (aka the new first point of least resistance). My point being (and presumably YNWOAN's above) is that the hardness mismatch between tool steel and ceramic will see the spindle end dimple enlarge much more rapidly. Should that enlargement eventually 'capture' the ball then the relatively much softer bearing well bottom has no chance.
Looking on the bright side, unless the bearing goes totally dry, none of us are likely to live long enough to hear the ball drop.
P.S. With captive ball bearings, or spherical spindle ends like that of Linn (and others before Linn, despite the patent grant), the bearing well typically has an equally hard polished thrust plate fitted.
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