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Multiple platter alignment, how to do

Posted: Fri Aug 10, 2018 12:33 pm
by slingshot
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Some of the physically damaged drives need the platters cleaning before rebuilding into donors etc, how are they being geometrically re-aligned ? Do you even need to align them or is it nonsense ? I'm curious as to what the technique is thats used for aligning multiple platters ?

$6,000,000 question :lol: :lol:

Multiple platter alignment, how to do

Posted: Fri Aug 10, 2018 9:21 pm
by Blizzard
Test a matching model drive. Copy some large multimedia files to the experimental drive. Mark and remove the platters. Replace the platters and recover the data. Keep a list of drives that are still functional after platter removal and replacement. If the spindle doesn't have a very tight tolerance you might have a different type of synchronization problem. Some refer to the 2 factors as horizontal and vertical synchronization. I prefer to think of the challenge as center alignment and platter synchronization.

Multiple platter alignment, how to do

Posted: Sat Aug 11, 2018 3:37 am
by slingshot
How do you mark them though ?

Multiple platter alignment, how to do

Posted: Sat Aug 11, 2018 9:41 am
by LarrySabo
Has anyone experimented with using a dial indicator/gauge to measure eccentricity? My thought was, perhaps mark each platter edge to facilitate restoring rotational alignment and use the dial gauge to measure eccentricity at that mark, to facilitate eccentricity restoration. I doubt it's feasible as micrometer precision is likely required. This book/article describes how they do it on a spin-stand. Not your average shop tool! LOL

Multiple platter alignment, how to do

Posted: Sat Aug 11, 2018 9:58 am
by slingshot
My thoughts are the human element of realigning the marked platters and how they would be to poor to be reliable. Yet, somehow small data recovery shops are managing to do this trick, somehow :?

Multiple platter alignment, how to do

Posted: Wed Nov 28, 2018 1:38 am
by emir_has
Hi

I have tested platter moving/removing on 3 WD disks. I have taken 2x2.5" and 1x3.5" WD disk. All 3 disks have 2 platters and 4 heads. On 2.5" disks I have unscrewed and moved upper plater and then screw back. After that I have started disk and they have been initialized normaly. It was not nesesery to align anything.
On 3.5" WD I have made same but disk start sliently to knock. So I entered in kernel mode and change heads in RAM (disabled heads 2 and 3) and then initialized the disk in normal mode. Backup of data in DE works fine. After that again in utility I have changed heads in RAM (disabled heads 0 and 1 and enable heads 2 and 3). In DE I have made backups of data but it seams that disk is slow. Speed of data copying was poor.
I dont know is it becaue i made some misslingement or the testing disk was poor.
This is share of my experieince. It was not to written to give some philosophy to you guys. Please consider it as my small contribution to community!

Thanks

Multiple platter alignment, how to do

Posted: Wed Nov 28, 2018 3:19 am
by pclab
Thank you Emir.

Multiple platter alignment, how to do

Posted: Wed Nov 28, 2018 8:47 am
by LarrySabo
Thanks @emir_has. That's very interesting and encouraging.

Multiple platter alignment, how to do

Posted: Thu Nov 29, 2018 5:54 am
by emir_has
I have forgot to mention that disks used for tests are WD blue 1x2.5" is 500GB; 1x2.5" 640GB and 1x3.5" is 500GB. Tested before platter moving with reading and writing and they seams OK with small number bad sectors.

Multiple platter alignment, how to do

Posted: Thu Nov 29, 2018 5:31 pm
by datahaze
slingshot wrote:How do you mark them though ?


I don't have experience doing this, but I've heard one can just mark the edge of the platter with a sharpie