Old, but not "Classic"

I'm Horology buff and this jewel thing, even longer time than many think about 300 years. Jewelled movements is VERY desireable than having anything else using hardened steel pivots in hammered-hardened brass bearings. Before around 1925 my guess crimped in loose jewels but after that, pressed in jewels. That technology was possible when jewels can be ground perfectly round and parallel sides with hole exactly in the centre, jewel material much stronger and purer than native jewels full of flaws and cracks easily. You can do hand install those pressed in jewels. I did that few times. Ball/roller bearings is another best bearings for some specific uses. I echo that, no majik there. Correct I have few books on this including the old style repairing. Not the that, your both statements is right and would might make sense because that head bearings would shatter if the drive is dropped and jewels can be made more closer in tolerences and last long time. Can't do that with bushings at all, hint: WD, miniscribes and few brands that used that. I think less friction is best to give best tracking and seeking with what little power you can use. This drive is sucking less than 500mA at run time. 1A is surge current to kickstart the spindle, unlock/undock the heads. Remember, that zip was designed to have battery power when it first came out and might be still true. Don't forget the bearing wear is extrended to hundreds years than just plain brass and steel but perfectly fine in well designed gears because they only rolls into and out together. Spindle still use ball bearings not jewels! Hehehe... But those babbit and steels does their job just fine because lube kept 2 parts by wedge action apart becaues of lube pressure and high enough rpm. Think: skating happens because of that water layer between ice and steel. I had to rebuild brass bearings types in anything and often those any movements not *that* old even younger than me! Time waster and murder on those steel pivots. In worst cases that simply wore out to a thin stem with a mushroom head that breaks off! Dress the steel pivots and burnish them, dry polishing with a hard burnisher stick, hand ream out those worn holes to size to accept the pressed in brass bushing then ream the pivot holes to size that only allow less than 5 degree wiggle or jewels if desired. The ream tool is 5 sided with sharp edges long, slow taper made of hard flexiable tempered steel in many sizes. Jason D. email: jpero(a)cgocable.net Pero, Jason D.