From: robin_listas@es.invalid   
      
   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   
      
   --   
   Cheers,   
           Carlos E.R.   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)