Old, but not "Classic"

From: jpero_at_pop.cgocable.net <(jpero_at_pop.cgocable.net)>
Date: Fri Nov 13 13:12:38 1998

> Date: Fri, 13 Nov 1998 18:47:37 +0000 (GMT)
> Reply-to: classiccmp_at_u.washington.edu
> From: ard_at_p850ug1.demon.co.uk (Tony Duell)
> To: "Discussion re-collecting of classic computers" <classiccmp_at_u.washington.edu>
> Subject: Re: Old, but not "Classic"

Snip!
 
> Sure. But be careful - there is an early movement around (I think
> 1650-ish) with a jewel on the end of the balance cock over the pivot, but
> it's for decoration only. It is not a bearing.

That's is called (oops long time I used that term, looking up the
horology book..ah!) Endstone. But that sometimes does let the
pivot ends to rest on it not it's shoulders to cut down friction by
huge margin. Stone or green-tempered polished steel fine as
endstone.

> The head positioned in that Seagate 1.3Gbyte drive I mentioned runs on
> ball bearings.

You're kidding if you only referring to this only drive? All hard
drives have the ball bearings for pivoting design and same thing
still in many linear types. Those ones that used rack and gear with
bushings. I hate that the platters were good but that simply wore
out. That only get in conflict with your next statement as shown in
next paragraph.

> Sure, but it's rare for a well-designed bush bearing, with suitable
> lubrication (which can be 'sealed for life' to last less than 10 years in
> this sort of application. And that's a lot longer than (I would guess)
> the design lifetime of most computer drives.

True... but steady loads and slow movement always have problems.
 
> I've _never_ had positioner bearing problems on any drive I've worked
> on. Not even the old DEC units on my -11s. I am not saying it can't
> happen, but that there are many more important things to fix first.

Which one? Sleeve or roller/ball bearings?

>
> -tony
>
Jason D.
email: jpero_at_cgocable.net
Pero, Jason D.
Received on Fri Nov 13 1998 - 13:12:38 GMT