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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > Backing off home switches in Mach 3 with soft limits?? Gerry??
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  1. #1
    Join Date
    Nov 2008
    Posts
    16

    Backing off home switches in Mach 3 with soft limits?? Gerry??

    I'm going to try to make this short and to the point, since everything else on my machine is working great, homing works fine, limit switches work fine.

    Is there a way to home a machine with soft limits turned on? I want to have my soft limits set an inch or so away from my limit switches as a buffer, but when homing, the soft limits are triggered. I read this post:
    http://cnczone.com/forums/showthread...tton%28&page=3
    which I thought would totally work, but it didn't. I added the code to my button script, and with the soft limits off, it works great and my machine homes, then returns to x0 y0, but with soft limits on, it starts homing and stops after it hits the switch and backs off and says soft limits exceeded.

    any ideas? I've tried the following scripts:

    DoButton( 24 )
    DoButton( 23 )
    DoButton( 22 )
    DoButton( 25 )
    Code "G1 G53 X0 Y0"

    DoButton( 24 )
    DoButton( 23 )
    DoButton( 22 )
    DoButton( 25 )
    While IsMoving()
    Wend
    Code "G1 G53 X0 Y0"

    DoButton( 24 )
    DoButton( 23 )
    DoButton( 22 )
    DoButton( 25 )
    While IsMoving()
    Wend
    Code "G0 G53 X0 Y0"

    Again, if soft limits are off, all of these work, and the machine homes, then returns to 0, but with soft limits on, it stops after the first soft limit is reached.

    Is there a code I can add to the beginning that will turn off the soft limits, then another code that will turn them back on at the end of homing?

    Thanks
    Jesse

  2. #2
    Join Date
    Jul 2007
    Posts
    887
    Hmm, that's weird, I played around a bit here and on my system I can't even turn ON the softlimits before I've homed/referenced the machine. Anyway, you could try something like this:
    Code:
    If GetOEMLED(23) Then     'Check if Softlimits are ON
     DoOEMButton(1029)        'Toggle soflimits
    End If
    DoButton( 24 )
    DoButton( 23 )
    DoButton( 22 )
    DoButton( 25 )
    Code "G1 G53 X0 Y0"
    While IsMoving()
    Wend
    If NOT GetOEMLED(23) Then     'Check if Softlimits are OFF
     DoOEMButton(1029)        'Toggle soflimits
    End If
    /Henrik.

  3. #3
    Join Date
    Apr 2007
    Posts
    8082
    I've not set this up before, but my understanding of this is that the soft limits should trip after passing through the home position. This is an over travel condition.

    CarveOne
    CarveOne
    http://www.carveonecncwoodcraft.com

  4. #4
    Join Date
    Mar 2003
    Posts
    35538
    No, he wants the machine to stop before tripping the limit switches.

    I don't have switches on my router to try it, but Henrik's code is what I was going to tell you.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  5. #5
    Join Date
    Jun 2004
    Posts
    6618
    You are probably aware of this, but I'll say it anyway. You can set the soft limits up right at you switches and have the soft limits implement a slow zone. This would effectively slow an axis way down before it actually hits a switch. I just assume that is why you want soft limits set before the switches.
    Lee

  6. #6
    Join Date
    Apr 2007
    Posts
    8082
    Quote Originally Posted by ger21 View Post
    No, he wants the machine to stop before tripping the limit switches.

    I don't have switches on my router to try it, but Henrik's code is what I was going to tell you.
    Ok. On my first machine I set up the ramps for the lever switches so that going past a switch then and backing up would not damage the switches. I know that there are many ways to do this.

    CarveOne
    CarveOne
    http://www.carveonecncwoodcraft.com

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