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Neat explanation of the planimeter

Discussion in 'Electronic Design' started by Robin, Jan 28, 2007.

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  1. Robin

    Robin Guest

  2. Sorry to hijack the thread. Can any one tell me why I can't post a new topic
    on this NG? It seems I can reply to threads, but not start one.Try as I
    may....
    Thx.
     
  3. John B

    John B Guest

    On 28/01/2007 martin.shoebridge wrote:

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    If you tell us which newsreader you are using it might help.
     
  4. (from the headers)
     
  5. john jardine

    john jardine Guest

    I've never seen a cheap office type planimeter, or one in use. Hopefully I
    looked at the site but am still none the wiser!.
    I'm seeing lots and lots of maths and line drawings and animations, lots and
    lots and lots of words and a couple of grainy pics.
    But absolutely nothing on what (to me) is the show stopping critical
    feature, of how the integrating wheel manages to accurately turn when being
    dragged near sideways over paper.
    I used to deal with Honeywell mechanical gas mass flow computers. Their
    integrating discs were an expensive, complex marvel of mechanical
    engineering but it was quite clear from watching them how the X-Y-(Z)
    forces resolved. Not so with these office devices .
    The planimeter site could have been vastly improved by offering up an mpeg
    of one actually in use.
    john
     
  6. File : New : News Message


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  7. jasen

    jasen Guest

     
  8. jasen

    jasen Guest

    low friction bearings, as long as the friction of the bearings is less
    than the dynamic friction of the wheel-rim it'll turn acurately.
     
  9. Glen Walpert

    Glen Walpert Guest

    The one I used back in the 70's had fine grooves on the surface of the
    wheel parallel to its axle, so it would slide sideways and roll
    lengthwise. Useful for rough estimates on preliminary designs only
    even then.
    Speaking of ancient mechanical curiosities, I recently uncovered some
    old operation and calibration instructions for a Bailey pneumatic PID
    controller, a "very very reliable" design from the 1940's, some of
    which are still in use today. I will scan the schematic diagram and
    post to ABSE for your entertainment.
     
  10. john jardine

    john jardine Guest

    Thanks. Fine bearing surfaces and the rim lines make good mechanical
    engineering sense.

    Blast from the past!. Yes I'd love to see 'em.
    Formative years in the 70's spent amongst petrochemical control rooms
    stacked out with 3-15psi Foxboro, Taylor, Kent, Honeywell etc control gear
    and some truly 'evil genius' pieces of air engineering which effected
    cascade control and computing functions. Every time I programme a sqrt
    routine on a PIC I think back to those massed ranks of Foxboro pneumatic
    'square root extractors' and marvel as to how easy it all is nowadays.
    john
     
  11. Glen Walpert

    Glen Walpert Guest

    I got busy for a while but finally got around to scanning and posting
    some unfortunately poor quality schematics to ABSE thread title
    "OT: Schematics of Bailey transmitters and PID controller"
    The transmitter square root mechanism and the controller gain
    adjusting mechanism are both interesting IMO.

    I haven't worked on any of these Bailey controls since '72, but I
    remember them like it was only 35 years ago. My memory was jogged by
    mention of a 2006 upgrade of a 1949 Bailey control system in Control
    Engineering. A 57 year service life for a control system is not too
    shabby.

    Glen
     
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