Re: FocusDrive and Interrupts

["Michael J. Mahon" <mjmahon@aol.com>]

On 11/1/2010 6:45 PM, D Finnigan wrote:
> Michael J. Mahon wrote:
> > This oscillating acceleration, together with the torque of the
> > motor, will often break the platters free, allowing the drive
> > to spin up.  When it does, don't shut it down until you've copied
> > its contents to another (working) drive.
>
> That's one of about three techniques which I've heard of. I've had success
> with it on regular-size Quantum mechanisms. I've also heard of the technique
> of leaving the drive in sunlight to warm up any stuck crud. This time, I
> wanted to try out the oven method.

The most common kind of stiction is head-to-platter stiction, in
which prolonged rest has allowed almost all of the air between the
flat surface of the (normally flying) head and the flat surface of
the platter to diffuse out, resulting in very close solid-to-solid
contact over a wider than usual area.  The result is higher static
friction forces than the motor can overcome.

Axial oscillation (as fast as can be controlled by hand) alternately
adds and subtracts from the motor's torque, frequently overcoming
the stiction and allowing rotation, and flight.

> > It may restart for awhile without further torquing, or it may
> > not, but it won't matter if you've copied its contents.  ;-)
>
> And it matters even less for I know that I had previously formatted it and
> installed 6.0.1 on it just 30 minutes earlier. ;-)
>
> As I'm sure you realize, this wasn't a "serious" effort to recover the drive
> and get it working. I was just curious to try out the oven technique.

OK.  ;-)

I would expect this to work if the "stiction" (not really) were the
result of partial congealing of the spindle lubricant, which has not
been a problem for a long time.

-michael

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