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  1. #1
    I've just set up a couple of switches to home my Y axis (the long one) which has two motors where A is slaved to Y in Mach 3.

    Could somebody help explain how to setup Mach 3 so the home switches on each side of the gantry work independently so that the gantry is automatically squared when I hit home?

    I had a go yesterday and for some reason the slaved axis carried on after it hit the switch and crushed it! Do I need to set them as limit switches too?


  2. #2
    Quote Originally Posted by Tenson View Post
    slaved axis carried on after it hit the switch and crushed it!

    for my own reference, keen to hear a response to this question... think my switches turn up this week.

  3. #3
    You need each switch on slaved axis on it's own input then go into Config/General config and unset the "Home Slave with master Axis".
    Should work now.!

    TIP: To test click the switches manually by hand well before axis gets near switches. Keep hand over E-stop just in case it doesn't work.. . .Simplizzz.

    Setting them has limits won't make any difference because Mach ignores Limits while it's homing when sharing switch.
    Last edited by JAZZCNC; 22-02-2013 at 12:09 AM.

  4. #4
    Quote Originally Posted by JAZZCNC View Post
    You need each switch on slaved axis on it's own input then go into Config/General config and set the "Home Slave with master Axis".
    Should work now.!
    That works fine for a single switch on a dual axis but if you want to home each of the two sides of the gantry independently ie. to auto square. then you leave this disabled. It could be you had this enabled and that's why it crushed your switch since it ignored one and looked only for the other.

    What you have to do is:

    • In general config set 'Home slave with master axis' to disabled
    • Make sure you have each of the two switches on a separate input to Mach. Auto squaring doesn't work with the switches in series on the same input. Note: You can have all your switches in series bar one of them on the dual axis thus using only two inputs if your restricted
    • In ports and pins correctly assign the inputs to the switches and test them to make sure their working as intended. Take care to ensure the correct switch corresponds to its associated axis. (assume you know how to do this since you already have working switches on your machine)
    • Check that your motor tuning is identical for the Master and Slave axis because once you start to home they run independently and are no longer slaved during that operation so Mach will use these settings - if they're different you'll twist the gantry.
    • Go into homing and soft limits setup and check that the Master and Slave axis settings are identical here too.

    Some additional advice. If your using the cheap mechanical switches ditch them, they really are shit. They bend so easily and not particularly accurate in general. If you can ensure that no swarf is going to get to them then inductive proximity switches are far better since there's no mechanical action. I use these and found them to be dead on accurate and its impossible to crush them - bonus! lol

    SN04-P 4mm Approach Sensor Proximity Switch PNP NO DC 10-30V 200mA New | eBay
    Last edited by Shinobiwan; 21-02-2013 at 11:51 PM.

  5. The Following User Says Thank You to Shinobiwan For This Useful Post:

  6. #5
    Good spot Ant.!! . . It should have read " Unset the "Home slave with master Axis" " . .

  7. #6
    Yep not just a pretty a face! Haha

  8. #7
    Ahh I'm still having trouble! If I select 'home slave with master' then it homes well, but only pays attention to the one switch on the master axis. If I don't have that ticked then it seems like it homes the master and slave at the same time and uses both switches which is good, but after it hits both switches and backs off it then seems to start homing the slave axis on it's own! It's tricky to know exactly what it's doing since I need to abort as soon as it tries to twist the gantry.
    Last edited by Tenson; 22-02-2013 at 12:58 AM.

  9. #8
    Did you follow the stuff above?

    Once mach hits a switch and backs off it doesn't try to home again so what you think is happening won't be the case. You'll have to dig deeper in the diagnostics and watch the pins to see if they light and go out as expected. Check wiring and go over all your settings thoroughly. Make sure your motor output pins for A, B, C aren't sharing too.
    Last edited by Shinobiwan; 22-02-2013 at 01:17 AM.

  10. #9
    It seems like it is homing the Y axis and the A goes with it as they are slaved and it does just what it should. Then it goes and homes the A axis independently like it thinks it is not only slaved, but also independent... I'll have another look tomorrow and probably twist the gantry!

  11. #10
    I fixed it! The problem was that I was hitting 'Ref All Home' which seemed to home Y with A at the same time since they are slaved then homed A independently. The solution was to go to the diagnostics page and click 'Ref Y' on its own rather than Ref All Home.

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