archiving data, was RE: Media Longitevity/Care

[jpero at sympatico.ca]

> What about RL02s?  Are they meant to be left alone once mounted and run 
> up, or can you treat them like big Zip disks?

Try to make adapter to convert from one interface to IDE interface 
and use CF card.  Smallest is 8MB all the way to 8GB and price is 
good on 1GB and below.  If one knows well with SD stuff, great!

> Turning brake discs is something I've never understood.  They're cheap. 
>   They're your *brakes*.  If the disc is scored or corroded, *throw the 
> pair away*.  For the amount of hassle that's involved, it's just not 
> worth doing it twice. </offtopic>

Agreed.
 
> > up an electroplating rig is easy enough (I copper plated a number of
> > nickels and quarters as a lad ;-) presuming one can a) come up with an
> > acceptable formula for the coating, and b) gain access to the various
> 
> I thought the coating was sprayed on?  Looking at the edge of an RL02, 
> there are clear "dribble marks" where it's run down the side of the disk.
> 
> 
> Gordon.

Platters are very hard high quality aluminum alloys, sliced from big 
round cast log, ground flat then lapped on large machines.

The Fe powder is very fine dust ground up and mixed with thin epoxy 
and squirted on slowly rotating platter near hub in one revolution 
and application of Fe mix stops then spun high rpm to spread the 
coating & fling excess off.  Again same process to apply 
special lube that stays on the platters since the coating is very 
smooth and wears smooth if it was honed.  This explains why the lube 
get worn off if the Fe coated HD is run too hot for too long, causes 
the heads to stick at shut down and cooled down.

This squirt & fling off spin process is still done with clear coating 
for the CDs.  Done in 2 seconds.   SPLAT!

Light grey to very dark grey, even reddish plating is usually cobalt 
or something else ferrous.  Plated on with platters rotating to get 
even coating.  Many you can see light spots where holding fixtures 
was.

You don't want very smooth platter for plated platters.  Sticks to 
heads for low density types.  It's finely honed like you do with 
cylinders in engines. In high density HDs like 10 GB and up per 
platter, the rest of platter is left very mirror-smooth except 
landing and taking off area (near hub) is laser roughened on purpose 
after plating process.  Cuts down on start up current demands and 
easier to get heads to take off and land softly.  Others left the 
rest of platter mirror smooth and use ramps to park the heads off the 
platters.   Done routinely in notebook 2.5" HDs and 1" and smaller.  
Many use this also on  many 3.5" platters models as well.

I recall that Lapine 3.5" HDs (MFM) was the first one to use ramps 
built into spring structure of head arm to get heads off the platters 
in mid 80's.  I had few of those and platters were smooth plated 
type and very stiction-y.  Startup: Stepper moves parked heads 
assembly pushing the fork of rods towards pivot area and locked by a 
claw on the sprung soleoid coil.   Power loss the soleoid simply 
loses power lets go of that claw that releases rods assembly.  
Rods assembly is sprung so it pivots out and heads simply get off the 
still spinning platters, no need to use stepper like seagate does.  
Clever design.  Uses free band driven stepper.

Some platters are made of glass.   Stopped using this stuff after 
problems surfaced on 3.5" size.  Remember the IBM deathstar era for 
several generations?  But still used on many 2.5" and less 
diameters.  Toshiba I know for sure exlusively use glass platters in 
their portable HDs.

Cheers,

Wizard