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Thread: Aligning Floppy Drives

  1. #51
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    I think this was actually a good thread to rebirth. Thanks for those adding their valuable input to it.

  2. #52
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    Quote Originally Posted by 1ST1 View Post
    I think it would be nice to reproduce this device:

    Attachment 53734

    Attachment 53735
    Olivetti CALT3. As an apprentize I used to work with that.

    Additionally to the CALT3 you need an Alignement Disk and an Oscilloscope and then you were able to realign all kinds of floppy drives.
    Interesting machine. So little info about it comes upon a Google search. Guess it was a special made using a modified Olivetti PC machine ?

  3. #53
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    Quote Originally Posted by Chuck(G) View Post
    If you want something fancier, you create your own alignment disks the way we did back in the day. We took a Micropolis 100 tpi floppy drive, mounted it on a 3/4' thick aluminum slab and gutted the innards of the leadscrew stepper and coupled the rear of the stepper shaft to a 100:1 precision reduction gear, driven by an external stepper, with a dial indicator to locate track 0 exactly. Micropolis was known for its precision-ground leadscrew arrangement--this is also what drove them out of the floppy market--leadscrew positioners are much more expensive to manufacture and also somewhat slower in 5.25" drives than taut-band models.

    We made our own alignment floppies. We discussed being able to vary the azimuth of the head as well, but never got around to implementing that.
    Would this contraption make 'analog' or 'digital' alignment discs?

  4. #54
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    With the right (pun intended), signal source, either.

  5. #55

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    Quote Originally Posted by exidyboy View Post
    Would this contraption make 'analog' or 'digital' alignment discs?
    No, you can not make an alignment disk. Even a disk drive that is said to be aligned will not make a valid alignment disk.
    You need fero-fluid, a microscope and a micrometer setup( or laser positioner for the heads).
    Dwight

  6. #56
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    I think you overestimate the requirements, Dwight. As I mentioned, we made our own 100 tpi alignment disks with a 100:1 reduction drive on the (leadscrew) positioner. They worked just fine.

  7. #57

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    Quote Originally Posted by Chuck(G) View Post
    I think you overestimate the requirements, Dwight. As I mentioned, we made our own 100 tpi alignment disks with a 100:1 reduction drive on the (leadscrew) positioner. They worked just fine.
    Ok, what about one of those drives with the snail spiral. Not all drives used a lead screw.
    Besides, your step time must have been really bad.
    The last setup I saw was for hard drive servo tracks and they use a LASER ( helped fix the software for that one ).
    Dwight

  8. #58

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    I just did a calculation. I did a control system for a XY table that had 24 inch travel that was better than 0.0002 inch location. That is about the same as your 100:1.
    I should have kept that table when they shut things down, or at least the lead screws and nuts.
    Dwight

  9. #59
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    Quote Originally Posted by Dwight Elvey View Post
    Ok, what about one of those drives with the snail spiral. Not all drives used a lead screw.
    Besides, your step time must have been really bad.
    The last setup I saw was for hard drive servo tracks and they use a LASER ( helped fix the software for that one ).
    Dwight
    Oh, it was a Micropolis 1016 II drive; normally 4 steps per cylinder. The drive was mounted on a 3/4" thick slab of aluminum along with the 100:1 precision right-angle reduction and the accomanying stepper. It took a couple of minutes to get from track 0 to track 76. But, back in the day, the Micropolis drives were the best of the best and darned expensive.

    One of my friends at around that time worked on a servo writer for Tandon hard drives. Yes, a laser interferometer and a pneumatic nitrogen-fed cylinder, all mounted on a granite slab.

  10. #60
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    Quote Originally Posted by inotarobot View Post
    Hi Chuck,

    Can you provide that Z80CPM code then please? Maybe put on BITSAVERS somewhere suitable?

    the 5 1/4" Dysan Alignment Disks I have are hand marked Digital Alignment Disks

    224/2A s/n EB268 which is hand marked 48tpi

    &

    506-400 s/n CU503 which is hand marked 96tpi

    also have a DYMET 3.5" 300rpm disk #301-12 s/n A217

    At the moment I cannot see my 8" drive Alignment Disk. It may be in my Storage
    I took a look at the 8" digital aligment disk from Dysan. It's an 800-series tape, complete with paper documentation on what's what--the program is attuned to that as far as I can recall. Do you have similar documentation for your 5.25" disk?

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