24 Nov
2008
24 Nov
'08
2:14 p.m.
if this was the case, the surfaces just needed to be plated, you can produce a uniform
thickness by polishing. Some sort of contraption (a lathe?) would be necessary, but
it's not rocket science I don't think. I was between jobs a number of years ago
and applied at this place in Long Island that makes some sort of microchips. The silicon
wafers needed to be made *uniform*, and they used some sort of polishing operation. I
asked what was the tolerance, and the guy said .0001". I figured to myself he
probably didn't really know what he was talking about and the tolerance was much
tighter. Cast iron surface plates can be made uniform to .000025" (that's right,
25 millionths of an inch), but that's an entirely different operation, and in fact is
done - by hand - w/a glorified chisel.
Carry on lads. I'm interested in learning more about this meself.
--- On Sun, 11/23/08, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
From: Brent Hilpert <hilpert at cs.ubc.ca>
Subject: Re: Hard disk material
To: General at invalid.domain, "On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Date: Sunday, November 23, 2008, 9:21 PM
Jules Richardson wrote:
William Donzelli wrote:
> It looks like sometime in the future I may need
to rebuild a damaged
> magnetic drum. It has some scratches that
may be
too deep. As a
> brainstorm, I am wondering about recoating
the
surface. If I use
> refined iron oxide, what would I use as a
fixer
(glue)? What was
> typically used on early hard disk platters
and
drums?
Seriously? Do keep us posted... far as I know,
it's not something that
anyone's ever tried before - it'd be
interesting to know how you get on. I'm
not even sure how you could coat a drum in glue /
oxide and get it of uniform
thickness without specialist tooling.
I've heard of low-speed, low-capacity homebrew
drums before, but it sounds
like you're hoping to rebuild a commercial
one...
Weren't drums and early disks done with nickel or
some-such plating, rather
than binder & oxide?
Of course, getting a uniform thickness of plating requires
careful attention as
well (spoken having had bitter experience with such).