Thread: 31 Jewels
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Old 17 February 2009, 08:21 AM   #20
BigHat
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Join Date: Sep 2007
Real Name: Matt
Location: Arlington, VA
Watch: Lange One MP
Posts: 4,043
Quote:
Originally Posted by elijahenoch View Post
JEWELS ? what are jewels Are they actual jewels?
Is this a serious question? If so, yes they are jewel bearings to minimize friction. Synthetic rubies in most cases.

From Wiki:
The advantages of jewel bearings include high accuracy, very small size and weight, low and predictable friction including good temperature stability, ability to operate without lubrication and in corrosive environments. They are known for their low static friction and highly consistent dynamic friction.[1] The static coefficient of friction of brass-on-steel is 0.35, while that of sapphire-on-steel is 0.1-0.15.[1][2] Sapphire surfaces are very hard and durable, with Mohs hardness of 9 and Knoop hardness of 2000, and can maintain smoothness over decades of use, thus reducing friction variability.[1] Disadvantages include brittleness and fragility, limited availability/applicability in medium and large bearing sizes and capacities, and friction variations if the load is not axial.
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