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  1. #1
    Hi

    I have a 3 axis Milling machine which i have converted to CNC with the help from members of this forum, i have installed, a maximum travel Limit Switch (Mechanical Lever Type) to each axis, wired through the PILZ relay i am using, so complete shut down on activation. I now wish to install "HOMING" switches, but which type ? Mechanical or Optical. I am using Mach 3 software, or can this be done in Mach 3. Can anyone supply the relevant info?

    Regards

    Ray

  2. #2
    Don't forget to include an over-ride switch, so when you hit the limit, you have some means of getting off it. "looking for a smiley that means - Painted into a corner"

  3. #3
    Hi.

    I have left the hand wheels on the motors for this purpose.

    Ray

  4. Optical or proximity would work, difficulty with either, on a mill as opposed to a router, is finding somewhere they can be kept clean and dry. Also where is 'home' on a mill? nominally its the centre of the table (as opposed to one corner on a router). Mach3 homing is to detect the homing switch change of state then back off til it changes back again. a bit tricky to do for the middle of the table.
    Quote Originally Posted by manofgresley View Post
    Hi

    I have a 3 axis Milling machine which i have converted to CNC with the help from members of this forum, i have installed, a maximum travel Limit Switch (Mechanical Lever Type) to each axis, wired through the PILZ relay i am using, so complete shut down on activation. I now wish to install "HOMING" switches, but which type ? Mechanical or Optical. I am using Mach 3 software, or can this be done in Mach 3. Can anyone supply the relevant info?

    Regards

    Ray

  5. Is this any use ? it might solve the issues Irving rightly brought up.

    http://www.cnccookbook.com/CCMillCNCHomeSwitches.htm
    Last edited by EddyCurrent; 13-07-2014 at 10:36 AM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  6. #6
    Thanks for the advice, i have a ZP5A BoB, the voltage on the Bob for the HOME limits is 5 volts, i am no electrician, could you recommend a type and brand of switch i could use?
    Quote Originally Posted by irving2008 View Post
    Optical or proximity would work, difficulty with either, on a mill as opposed to a router, is finding somewhere they can be kept clean and dry. Also where is 'home' on a mill? nominally its the centre of the table (as opposed to one corner on a router). Mach3 homing is to detect the homing switch change of state then back off til it changes back again. a bit tricky to do for the middle of the table.

  7. #7
    If you use a proximity switch such as the LJ12A3-4-Z/BX, you will need a supply voltage of 6 to 36v. anything below 10v won't work reliably (I found to my cost). The advantage of this proximity switch is that it is a sealed unit, you just need to keep swarf away from the sensor end.

  8. Quote Originally Posted by cropwell View Post
    If you use a proximity switch such as the LJ12A3-4-Z/BX, you will need a supply voltage of 6 to 36v. anything below 10v won't work reliably (I found to my cost). The advantage of this proximity switch is that it is a sealed unit, you just need to keep swarf away from the sensor end.
    Which is tricky on a mill, also the mill itself is a big chunk of iron so mounting proximity switches so they're not affected isn't so easy. Optical sensors as shown in the link on Eddie's post in suitably sealed boxes are a neater solution. A suitable sensor is this one: http://uk.farnell.com/omron-electron...ive/dp/1348961

  9. #9
    I f i read it right, this unit you recommend is fixed on the mill bed and a peice of metal is attached to each axis, the metal inserts between the 2 posts of the switch and makes the contact?
    Quote Originally Posted by irving2008 View Post
    Which is tricky on a mill, also the mill itself is a big chunk of iron so mounting proximity switches so they're not affected isn't so easy. Optical sensors as shown in the link on Eddie's post in suitably sealed boxes are a neater solution. A suitable sensor is this one: http://uk.farnell.com/omron-electron...ive/dp/1348961

  10. #10
    Quote Originally Posted by manofgresley View Post
    I f i read it right, this unit you recommend is fixed on the mill bed and a peice of metal is attached to each axis, the metal inserts between the 2 posts of the switch and makes the contact?
    Yes its an optical switch that is to say an invisible beam of light it being shone across the gap in the sensor and then when use pass a piece of dark plastic or metal into the gap it breaks the beam and triggers. ..Clive

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