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  1. #1

    Join Date
    Jan 2019
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    30

    Software limit

    Is there a way to set up a software limit in usbcnc so that the spindle can not go any further than the set limit. I do not have homing switches on my machine and currently I'm running the machine in the middle of the bed so I have no fear of crashing into the x negative and positive limits. And no chance of hitting the y negative and positive limits as well. But because I have a 4 axis machine, my z axis gets hit on the negative (up) frequently because it only leaves me about 20 or 30 mm of travel from the top of the part. And that's a generous estimate.

    Is there a way to set the software with a ceiling so it won't allow the z axis to go any higher than a certain height. I realise I may have to reset this limit each time I run a part but I'd rather do that than ruin expensive parts on my machine.

    Yes I'm aware homing switches are cheap but I don't have the money to buy them right now and unless someone is sending me some free ones that won't work.

    So I need a software based solution. Is there anything like that built into usbcnc or a workaround I can use to do it?

    Thank you in advance.

  2. #2
    Moderator PlanetCNC's Avatar
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    Mar 2017
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    238

    Re: Software limit

    Yes, you can set "Motor Limits" and/or "Motion Range".

  3. #3

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    Jan 2019
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    Re: Software limit

    That's in plantcnc tng, I'm using usbcnc. Are they interchangeable. Is tng just the newest version or something. And can this be done in usbcnc or is this option only available in tng.


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  4. #4
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    Aug 2011
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    957

    Re: Software limit

    Go to "Axes" in settings, specify the desired limits in "Limits" and activate the soft limits under "Soft Limits".
    It is kind of self explanatory.
    Box Joint and Dovetail CAM software here: WWW.TAILMAKER.NET

  5. #5

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    Jan 2019
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    30

    Re: Software limit

    Thank you. And no it's not exactly self explanatory. To me a soft limit can be exceeded and a hard limit is one that could not be exceeded. That's what soft limit means. That's why I didn't check it. But even had I known that it wouldn't have helped because it's greyed out and I can't check it. So what do I have to do to get it to work?


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  6. #6
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    957

    Re: Software limit

    Quote Originally Posted by cammel8 View Post
    Thank you. And no it's not exactly self explanatory. To me a soft limit can be exceeded and a hard limit is one that could not be exceeded. That's what soft limit means. That's why I didn't check it. But even had I known that it wouldn't have helped because it's greyed out and I can't check it. So what do I have to do to get it to work?
    Sent from my iPhone using Tapatalk
    Not sure why greyed out. On my machine with MK2 and another one with MK3/4 the soft limit controls are active, even when the machine is not connected. Maybe Planet CNC has an explanation for that.

    As for the "soft limit" definitions, I am under the assumption that only means "limit in software" (vs. hardware switches). But when activated, they are just limits and the machine is not allowed to go beyond them. You can also activate deceleration when approaching these limits to avoid step loss due to sudden stop. Another recommendation is to activate g-code check to get a warning if the soft limits will be exceeded before running the program and getting unexpectedly stopped in the middle of the run.
    Box Joint and Dovetail CAM software here: WWW.TAILMAKER.NET

  7. #7
    Moderator PlanetCNC's Avatar
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    Re: Software limit

    You probably have Chinese knock-off controller. They are based on our first Mk1 controller which an obsolete and not supported item. Many of their features are outdated and there is no software/firmware development.

    Mk1 controller does not support soft limits.

  8. #8

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    Re: Software limit

    Quote Originally Posted by PlanetCNC View Post
    You probably have Chinese knock-off controller. They are based on our first Mk1 controller which an obsolete and not supported item. Many of their features are outdated and there is no software/firmware development.

    Mk1 controller does not support soft limits.
    How do I find out what I have


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  9. #9
    Moderator PlanetCNC's Avatar
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    Re: Software limit

    You do have Chinese knock-off controller unless you made it yourself.

    It is a good chance that it is JP-382c:
    https://planet-cnc.com/replacing-chi...rv-controller/

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