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How do I setup a Z-down (+Z) Home/Limit switch?

Discussion in 'Mach3' started by Anonymous, Feb 16, 2009.

  1. Anonymous

    Anonymous New Member

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    With the -Y Home/Limit switch setup, when I hit "Home Printer" the PhlatPrinter will drive the gantry toward -Y until it hits the switch, then automatically reverse at 20% speed until it's just off the switch, then reset the digital read-out (DRO) for Y to 0.0000. It's really cool to watch, and Y is exactly at the same place every time. So I decided to add a switch for a +Z Home/Limit switch.
    That's when things got weird. In the "Config" "Ports and Pins" "Input Signals", if I enable "Z-Home" (port 1, pin 12)(Active Low), I can go to the "Diagnostics Alt-7" screen and "Ref Y" or "Ref Z" and they will act just like they're supposed to.
    But - if I click on either of the normal "Home Printer" buttons (like I did before adding and activating that switch), the Z-axis will try driving to China, ignoring the limit switch altogether. I must click the "STOP" button to keep it from self-destructing. If I de-activate all the Z settings, everything acts like normal.
    So then I activated the "Z++", "Z--" settings also (same port and pin), but when running ANY PhlatCode, the first operation is to drop Z to +0.050, which naturally hits the limit switch and shuts the cut-file down. Maybe there is some way to set the software to think that ZERO is 0.060" above the switch, so when it goes to +0.050 it still won't hit the limit switch. I can't figure out how to do that either.

    So - - Does anyone else have a Z limit switch on their machine? If so, how is yours configured?
    I think mine might be acting weird because of the SmoothStepper, so I'm going to post this on their forum also, but any help y'all might have would be greatly appreciated.
     
  2. WW8S

    WW8S Member

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    Dorsal, in most of the control software we use at work, there is an offset that can be programmed that moves the axis so many steps away from the switch before setting zero. Any chance this feature is available and you are overlooking it? (I'm not near my machine to see) I really like your homing idea and will incorporate it into my machine.
    Dave
     
  3. Anonymous

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    Dave, there are a couple of screens that seem to allow for the creation of an offset, but I couldn't figure out how to get them to work correctly. The fact that all our plunges in Z are in the Negative direction really confuses me. Do I need to set the offsets in negative numbers, or double-negative numbers?? :?
     
  4. Anonymous

    Anonymous New Member

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    I gave up on the offset idea and simply mounted another limit switch below the Home switch, so the gantry contacts the Home switch first, then the backside of the Home switch presses against the Limit switch (0.065" later).
    Funny thing is, the software still doesn't care. Referencing each axis or "Reference All" works great. And the gcode now works, because I wasn't striking the limit switch. But click on either "Home Printer" button and Z is going to drive to China, nonstop. :eek:

    I wonder if my Z chip has gone funky? What kind of hassle will it be to swap the Z chip with the X chip? :geek:

    otoh, Maybe I should just beg some help from Mark's programmer friends to turn the "Home Printer" buttons into "Ref All Axes" buttons on my computer. :idea:
    How hard is it to edit the screen and "button" functions in Mach?

    Any suggestions :?:
     
  5. Anonymous

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    (hmmph - There I go again talking to myself! )
    Might as well just go out there and pry those chips out with a bent nail and get it over with. Afterall, wasn't it Frank who found where new ones could be bought for about $6 each, and that's not so bad.
    It's not like I never muddled through something like this before anyway.
    Now, where's that stupid coffee cup?
     
  6. Evil-Tunes

    Evil-Tunes Moderator Staff Member

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    It's not hard to edit the screen buttons There is a wiki page on it http://www.machsupport.com/MachCustomiz ... =Main_Page

    There are buttons on the other screens (MDI ALT2) DE-Ref all Axes or (offsets alt5) Ref All Home . If you can get them to work I can move a button to the main screen for ya.
    I cant look now have to get some sleep will try tomarrow for ya.


    Cheers
    E-T
     

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