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Quick question about soft limits.

Discussion in 'CNC Mills/Routers' started by jda70az, Jun 7, 2021.

  1. jda70az

    jda70az Well-Known
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    Hi

    So after I HOME my machine it says on the Interface screen...
    X 80mm
    Y 30mm
    X 0mm

    Only reason it says that is after homing I pressed Zero all. Usually it's
    some number like -47mm -276.4 mm - whatever. You get the idea.

    Anyway ...the Soft Limit on the Y axis is set to 750mm
    I jog the Y axis out to 750mm and it doesn't stop. It stops at 774.6mm.
    If I jog back towards home it doesn't stop at 30mm and I tried to go to 0mm
    but it looked like it was going to crash into the limit switch.

    So how do you set this up properly?
    I just want it to not go past the travel limit of where it is when I Home the machine
    and out past 750mm.

    My spoil board to 24" x 30" / 609.5mm x 762mm
     
  2. jda70az

    jda70az Well-Known
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    Never mind I figured it out.:thumbsup:
     
    Rachel Holley and sharmstr like this.
  3. Gary Crews

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    Would you mind sharing your finding? I am having the same issue. Thanks.
     
  4. Misterg

    Misterg Veteran
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    I suspect that the poster above was mixing machine coordinates and work coordinates.

    Could you describe in a bit more detail the issue that you're having?
     
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  5. Gary Crews

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    I went downstairs to duplicate the error so I could get the proper syntax and had an epiphany ( I think). After homing I set XYZ zero to that point. When I would jog away and select GOTO Zero I would get an error about exceeding limit. I tried jogging off the 0,0,0 and set that as XYZ 0 and everything seems to work. Maybe you can let me know if that makes sense. I read a post that had similar guidance but go confused with other stuff I read.
    Thanks for the quick response!
     
  6. Misterg

    Misterg Veteran
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    That does make sense: When you click the 'XYZ Goto Zero' button, the default action is to try and raise the tool above work Z zero (by 5mm, I think) before moving X or Y, and then to lower the tool to work Z0 at work X0,Y0. This makes sense for people who set Z0 as the top of the work or the spoil board where a move in X or Y at Z=0 could result in the tool dragging across the stock / spoil board. If you have set Z 0 at the homed position, however, the Z axis will be almost as high as it can go, and there isn't enough Z travel available to raise another 5mm, hence the error.

    You can still move to that position, but you would need to use the second option on the XYZ Goto Zero button which uses machine coordinates to raise the Z axis (NB the machine must have been homed):

    goto0.png

    For most practical purposes, I think you'll find yourself setting Z0 at the stock or spoil board so this issue won't arise.

    I hope that makes sense. If not ask again :)

    (As a separate issue: If you're using soft limits on an X32 controller, make sure $40=1 in the settings - background info here:

    Soft Limits and Max Travel )
     
    #6 Misterg, Jan 1, 2024
    Last edited: Jan 1, 2024
    Peter Van Der Walt and Giarc like this.
  7. Gary Crews

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    Good info/answer, Thanks!!!
     
    Misterg likes this.
  8. David the swarfer

    David the swarfer OpenBuilds Team
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    the interface screen shows WORK coordinates, which will be relative to where ever you last setZero (which is relative to home).
    maybe this will help.
     

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