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Cake day: June 17th, 2023

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  • Descriptive Geometry.

    Basically obsolete by the time of mastering the techniques due to CAD software.

    Here’s lesson notes from somebody.

    https://www.archweb.com/en/gallery/descriptive-geometry-lessons/

    The field starts out simple with orthographic projections, but later you work on problems like : you have a top view of a 3D tube angled in space and another tube crossing it at an arbitrary angle, and then another view.

    Find this smallest distance between the two tubes in space.

    Neither are down the tube axis, so you start the process if finding the axes and producing a head on view to develop the crossing tube to then find a point to point minimum measure between the two cylinders.

    By the time I’d gone through all this, in CAD you just click the two tubes and ask for the distance (min or max)


  • There’s a way to do it without shrinking the partition and dd until last used block.

    I use this to copy my Linux setup for a nas down to a 4 gig ISO for redeploy.

    Have to check my notes…

    Edit: Checked Notes

    #Use-case of fdisk taking the approach that fdisk is used, and assumption is your "sudo fdisk -l " produced:

    Disk /dev/sda: 64.0 GB, 64023257088 bytes
    255 heads, 63 sectors/track, 7783 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x0000e4b5
    
    Device Boot Start End Blocks Id System
    /dev/sda1 * 1 27 209920 83 Linux
    Partition 1 does not end on cylinder boundary.
    /dev/sda2 27 525 4000768 5 Extended
    Partition 2 does not end on cylinder boundary.
    /dev/sda5 27 353 2621440 83 Linux
    /dev/sda6 353 405 416768 83 Linux
    /dev/sda7 405 490 675840 83 Linux
    /dev/sda8 490 525 282624 83 Linux
    

    The two things you should take note of are

    1. the unit size, and
    2. the “End” column.

    In this case you have cylinders that are equal to 8225280 Bytes. In the “End” column sda8 terminates at 525 (which is 525[units] * 16065 * 512 = ~4.3GB)

    dd can do a lot of things, such as starting after an offset, or stopping after a specific number of blocks. We will do the latter using the count option in dd. The command would appear as follows:

    sudo dd if=/dev/sda of=/your_directory/image_name.iso bs=8225280 count=526

    Where -bs is the block size (it is easiest to use the unit that fdisk uses, but any unit will do so long as the count option is declared in these units), and count is the number of units we want to copy Note that we increment the count by 1 to capture the last block).

    Note to display units in cylinders: fdisk -l -u=cylinders /dev/sda Note for newbies of dd that of= can be a device you write to i.e. /dev/sdc, rather than a path to an iso image.










  • BCsven@lemmy.catomemes@lemmy.worldIt’s a conspiracy
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    5 days ago

    I have been watching with described audio subtitles because a lot of times they capture stuff that you’d never hear or pay attention to. Like an exiting character’s background conversation with another character which is barely audible will be written out.



  • The oil pressure gauge does not tell you how high the sump level is. I.e shut the engine off, pump makes no pressure but sump could be high. The oil pressure gauge ( not a low oil level warning light) shows increments of pressure in your engine block channels which is unrelated to oil level, unless you have run the sump dry and are trying to pump air. But even with a full sump, oil presdur varies by engine temperature, and other flow issues like blocked oil filter or a filter that switched to bypass mode. How is it that you cannot comprehend these things dude LOL



  • So now you resort to trolling? Dude, by your other comments its clear you don’t understand cars of fluid systems. You were claiming OBD doesn’t work with car running.

    Oil pressure is created by your oil pump, not by the volume of oil you hold in the sump, its not a head well. But the pressure you read changes by a lot of factors, which I attempted to educate you on.

    Its sad that you have dug in and can’t see that.



  • Oil level is not oil pressure, they are different issues.

    You missed the whole part about trending changes and maintenance prediction.
    Oil pressure shows you live, what is happening inside the engine. Its why Race cars , Drag Cars have giant gauges for oil pressure, etc.

    Yourportion you clipped from wiki, further proves my point. Its for idiots that didn’t watch their gauges.

    Of course as a car guy you check oil level, coolant level, brake fluid level, but you want live data so you know what happening when engine is running. You can prevent failure before any warning light will.

    Maybe you are a computer guy: do you want your PC shutting off to thermally protect itself without warning, or do you want to compare fan rpm and CPU temp trends to spot if you have thermal issues rising. Which could indicate thermal paste issue, or you have some other thing loading the system when you thought it was just your game.

    People that can glean info from daily data trends know why gauges are important, even on industrialmachineas. Idiots just want a light to tell them something is already failing. It’s the difference between reactive maintenance and proactive maintennace.