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  1. #1
    Continuing with my Fehlmann mill-drill conversion, I have been sorting out what might be referred to as the W axis, that is the coarse positioning of the milling head. The machine as originally designed uses a microswitches and stops to obtain three user settable positions of the head. This vid from a couple of years ago shows the head and stop arrangement

    I've had this working with the stops but they only appear to be repeatable to about 0.1mm - which will mean tool height setting every time the head is moved.

    I was intrigued to find that Fehlmann continued developing my machine until about 2011 with the later Picomax 54 and 55 being almost identical but with CNC control of the W axis. Seen here:



    The Picomax 54 uses the same motor as in my P50 but has a rotary encoder on the end of the pinion shaft - I'm sure Fehmann's rack and pinions are very accurate but it doesn't seem like the greatest way of obtaining positional info. The motor is controlled by a VFD and somehow this controls the position of milling head using info from the encoder.

    I think that the Picomax 55 is doing the same thing but with a glass scale - I'll check with Fehlmann.

    Can anyone illuminate me about how it is possible to use an induction motor, inverter and encoder to obtain absolute position? I see this clever chap manages to achieve it:

  2. #2
    Clive S's Avatar
    Lives in Marple Stockport, United Kingdom. Last Activity: 15 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 3,333. Received thanks 618 times, giving thanks to others 78 times. Made a monetary donation to the upkeep of the community. Is a beta tester for Machinists Network features.
    Can anyone illuminate me about how it is possible to use an induction motor, inverter and encoder to obtain absolute position? I see this clever chap manages to achieve it:
    This is a vid by Andy Pugh He is on the LinuxCnc forum and I think he is also a developer.
    ..Clive
    The more you know, The better you know, How little you know

  3. The Following User Says Thank You to Clive S For This Useful Post:


  4. #3
    Thanks Clive, I'll drop him a line.

    David

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