From: jjb@invalid.invalid   
      
   On 20-05-2025 02:17, Carlos E. R. wrote:   
   > On 2025-05-19 18:05, Paul wrote:   
   >> On Mon, 5/19/2025 6:22 AM, Carlos E. R. wrote:   
   >>> On 2025-05-19 12:14, Paul wrote:   
   >>>> On Mon, 5/19/2025 5:28 AM, Carlos E. R. wrote:   
   >   
   > ...   
   >   
   >>> Yes, it is an air breather, I noticed the hole covered with some kind   
   >>> of gauze or filter.   
   >>>   
   >>> They could just fill with nitrogen, if helium is expensive.   
   >>>   
   >>>>   
   >>>> The platters are thinner, when there are a lot of platters   
   >>>> in there, so they don't have to be as heavy as the platters   
   >>>> in a four platter drive.   
   >>>   
   >>> I guess. This is not a fridge sized disk, after all :-)   
   >>>   
   >>   
   >>   
   >> There was a press release some time ago, indicating they were   
   >> working on thinner platters, in order to squeeze more platters   
   >> into the one inch high drive housings. The thin platters may   
   >> be made of glass, and then the plated-up stack is put on the   
   >> outside.   
   >>   
   >> *******   
   >>   
   >> It's a good question why they couldn't use Nitrogen. Or for that   
   >> matter, why the air-HDA could not be sealed. Helium might have a   
   >> different viscosity, and "flying characteristic" for the head,   
   >> which is why the Helium pressure is a bit above atmospheric.   
   >>   
   >> The air breather drives were supposed to be that way, to avoid   
   >> "tin-canning" of the lid, as barometric pressure changes. The Helium   
   >> drives on the other hand, have two lid plates, one gas-tignt, one   
   >> plate a mechanical reinforcement. If they used a fancy lid, I don't   
   >> see why they couldn't seal the air-based drive. The data recovery   
   >> people aren't going to like it. There have already been some   
   >> joke videos, where they portray their attempts to try to get the lid   
   >> off a Helium drive (welded on), for data recovery.   
   >>   
   >> It means if you have a Helium drive, and you let it get too old and   
   >> crusty, data recovery might be more difficult (or do-able by fewer   
   >> people), than the air drives that unscrew easily.   
   >>   
   >> The head stack in a Helium drive, would only have the correct flying   
   >> height under Helium fill to the correct pressure. If the housing   
   >> was filled with air, it is unclear whether you could even make it work   
   >> well with air present. The heads have "lift" and the lift surface   
   >> is scaled according to the gas being used. The "lift" effect counteracts   
   >> the spring constant of the arms. The flying scheme allows the drive   
   >> to run on six-axis.   
   >   
   > They might even use hydrogen. It is a similar density to helium but far   
   > easier to obtain. Yes, it is flammable, but there is not that much gas,   
   > and it is sealed.   
   >   
   > Well, welding is a problem, though :-DD   
   >   
     The problem with hydrogen might be that it diffuses easily in/through   
   materials.  In the long run it might affect the pressure within.  It   
   also makes metals brittle.   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)