"Soft" hard drive mounting.... - Page 2

Rob Withey · 12-22-2003, 01:11 PM

Quote: Originally Posted by none

I'd love to see the numbers you refer to.

My source is http://www.hgst.com/hdd/support/table.htm Contains a list of lots of Hitachi/IBM drives, which I believe are representative. Taking a random selection of operating shocks:

DK23EB-40 Laptop drive: Operating shock 250G 2ms half sine.
DK23EA-60 Laptop drive: Operating shock 250G 2ms half sine.
Travelstar 5K80 Laptop drive: Operating shock 200G 2ms half sine.
Travelstar 7K60 Laptop drive: Operating shock 200G 2ms half sine.
Deskstar 7K250 Desktop drive: Operating shock 55G 2ms half sine.
Deskstar 37GP Desktop drive: Operating shock 65G 2ms half sine.
Deskstar 22GXP Desktop drive: Operating shock 65G 2ms half sine.
Ultrastar 146Z10 Desktop drive: Operating shock 45G 2ms half sine.

Rob

Sh0cker · 12-22-2003, 01:33 PM

Im just curious, does hair gel conducts the heat fast? What do you think, would it be a good idea to sink the harddrive into the enclosure filled with the gel to prevent the shakiness? If not, what other substance can be substitudet with ehough thick gel consistence to hold it up and get the heat out so the hdd wont overheat.

hijinks21 · 12-22-2003, 01:35 PM

sinking a drive into anything is a bad idea. you'll have a heat build up then the drive will die

none · 12-22-2003, 01:43 PM

Interesting. Thanks. I'm trying to find some info on their testing standards but could not, do you have any info about this?

Interesting because it contradicts my personal experience.

Quote: Originally Posted by Rob Withey

My source is http://www.hgst.com/hdd/support/table.htm Contains a list of lots of Hitachi/IBM drives, which I believe are representative. Taking a random selection of operating shocks:

DK23EB-40 Laptop drive: Operating shock 250G 2ms half sine.
DK23EA-60 Laptop drive: Operating shock 250G 2ms half sine.
Travelstar 5K80 Laptop drive: Operating shock 200G 2ms half sine.
Travelstar 7K60 Laptop drive: Operating shock 200G 2ms half sine.
Deskstar 7K250 Desktop drive: Operating shock 55G 2ms half sine.
Deskstar 37GP Desktop drive: Operating shock 65G 2ms half sine.
Deskstar 22GXP Desktop drive: Operating shock 65G 2ms half sine.
Ultrastar 146Z10 Desktop drive: Operating shock 45G 2ms half sine.

Rob

tom2112 · 12-22-2003, 01:51 PM

Quote: Originally Posted by Sh0cker

Im just curious, does hair gel conducts the heat fast?

Ask Michael Jackson!!

Rob Withey · 12-22-2003, 02:00 PM

Quote: Originally Posted by none

I'm trying to find some info on their testing standards but could not, do you have any info about this?

2ms half sine shock (ie, single shock, no oscillation) pretty much defines it. The G rating defines the maximum acceleration with 1G being freefall off course. I don't understand which bit you don't understand about this - the forces experienced by the drive are completely defined.

For vibration the ratings are significantly lowered, since you can send parts of the drive into oscillation, which is also why sprung supports for drives are bad.

Personally I have opted for a set of stiff rubber washers to take the edge off the shock to my laptop drive, but not allow the thing into oscillation. Haven't had a single problem in over 4 years of operation.

Rob

none · 12-22-2003, 02:22 PM

Thanks for the info, but that doesn't tell me a thing about how the tests were conducted. I've done some research of my own, however, and these numbers are fairly consistent with those from other manufacturers.

Quote: Originally Posted by Rob Withey

I don't understand which bit you don't understand about this

Did I say I didn't understand something? I was merely asking for more information about the testing methods (what testing equipment was used, what constitutes a failure, who did the testing,) not an explanation of g-forces.

But thanks for the data.

Rob Withey · 12-22-2003, 02:38 PM

Quote: Originally Posted by none

Did I say I didn't understand something? I was merely asking for more information about the testing methods (what testing equipment was used, what constitutes a failure, who did the testing,) not an explanation of g-forces.

Ah, I understand...! A failure here is defined by loss of data (not a complete drive failure). Not sure of the other stuff, I haven't read the datasheets to that detail.

none · 12-22-2003, 02:44 PM

Thanks Rob.

Don't bother reading the datasheets for my benefit (if you were considering doing so which I'm sure you weren't

) I see clearly enough now that my personal experience must have been tainted by other factors. I am the cynical type, so I tend to not take manufacturer's specs at face value, but consistency with other brands is usually enough to convince me.

telekineticfool · 12-23-2003, 12:06 AM

Quote: Originally Posted by Rob Withey

The G rating defines the maximum acceleration with 1G being freefall off course.

Wouldn't freefall be 0g, not one?

Also, it would make sense that a smaller diameter disk would be more shock resistant even if they were the same material, from a dynamics point of view...oscilations and shocks generated at the hub would be magnified by the time they reached the outer portions of the platters, and if the platter diameter is higher.

If a disk's diameter is double, the displacement at the edge of the platter based on the shock will be double as well...so it will only be able to handle half of the shock load. Simple physics.

deadweasel · 12-23-2003, 01:53 AM

Personally, I try to avoid getting into rotational physics modeling, but mostly because it just makes my head spin.

*leaves before the tomatoes start flying*

Rob Withey · 12-23-2003, 05:16 AM

Quote: Originally Posted by telekineticfool

Wouldn't freefall be 0g, not one?

Nope. g = 9.816m/s^2, acceleration due to gravity. 0g is no acceleration at all, ie, sitting in your PC at rest.

Quote: Originally Posted by telekineticfool

Also, it would make sense that a smaller diameter disk would be more shock resistant even if they were the same material, from a dynamics point of view...oscilations and shocks generated at the hub would be magnified by the time they reached the outer portions of the platters, and if the platter diameter is higher.

If a disk's diameter is double, the displacement at the edge of the platter based on the shock will be double as well...so it will only be able to handle half of the shock load. Simple physics.

Yep, the displacement would be larger, not sure about double (assuming the thickness of the platter is the same). Another contributing factor is the length of the arm to move across the disk. The larger the disk, the longer the head.

Rob

deadweasel · 12-23-2003, 10:03 AM

Quote: Originally Posted by Rob Withey

Nope. g = 9.816m/s^2, acceleration due to gravity. 0g is no acceleration at all, ie, sitting in your PC at rest.
Rob

Not a physics major here, but I was wondering: doesnt G force rating indicate rate of acceleration increase relative to rest? In other words, once you are at freefall state, there is no longer any acceleration acting upon you, so how could there be a measurable force? Take, for instance, sleeping in a car. As long as the driver keeps the same speed, and doesn't change lanes, you may forget that you are travelling at any speed until the speed/direction actually changes, thereby subjecting you to an amount of force.

Just wondering, because I am a curious bastard who will probably find a way to test this out in the most exciting (IE dangerous) way possible!

lopan · 12-23-2003, 12:13 PM

I've had an Empeg for the last 3 years, I've never lost a drive and I use it at least 2 hours a day. I have two 30gig Toshiba laptop drives. The empeg has a shock plate built in, perhaps something like this could be adapted. Pictures can be seen here http://www.riocar.org/modules.php?op...ade&file=index

shakes · 12-23-2003, 12:41 PM

Quote: Originally Posted by deadweasel

Not a physics major here, but I was wondering: doesnt G force rating indicate rate of acceleration increase relative to rest? In other words, once you are at freefall state, there is no longer any acceleration acting upon you, so how could there be a measurable force? Take, for instance, sleeping in a car. As long as the driver keeps the same speed, and doesn't change lanes, you may forget that you are travelling at any speed until the speed/direction actually changes, thereby subjecting you to an amount of force.

Just wondering, because I am a curious bastard who will probably find a way to test this out in the most exciting (IE dangerous) way possible!

according to www.thefreedictionary.com :

Quote:

Noun 1. g-force - a unit of force equal to the force exerted by gravity; used to indicate the force to which a body is subjected when it is accelerated

and then at www.wordiq.com

Quote:

g (also gee, g-force or g-load) is a unit of acceleration defined as exactly 9.806 65 m/s², approximately equal to the acceleration due to gravity on the Earth's surface. Gravity due to the earth is experienced the same as being accelerated upward with an acceleration of 1 g. The total g-force is found by vector addition of the opposite of the actual acceleration (in the sense of rate of change of velocity) and a vector of 1 g downward for the ordinary gravity (or in space, the gravity there). Weightlessness means a zero g-force, which is the result when acceleration due to movement is equal to that due to gravity.

when you start a free fall, you accelerate up until you hit terminal velocity. even then, however ... you are still experiencing 1g of force even tho you are no longer accelerating. the earth's gravitational pull is still acting on you attempting to pull you faster, you simply don't go any faster because of the frictional force of your body.