Welcome to Our Community

Some features disabled for guests. Register Today.

Hard Limit Triggers under load + other questions.

Discussion in 'CAM' started by Blake Barr, Apr 28, 2020.

  1. Blake Barr

    Builder

    Joined:
    Jun 2, 2019
    Messages:
    11
    Likes Received:
    9
    I do mostly aluminum machining but i have started branching into mild steel. I have run into a random hard limits while the program is running and I am unsure why. I run my machine pretty aggressive for most peoples taste but ive tried so many things. Once the hard trigger is set, i rerun the program and as soon as it gets to the same spot it set the hard trigger the first time, it does it again. I can sometimes get by the trigger for a short time by running the feed rate and literally 10% of normal but it will eventually trigger the hard limit.

    Another question is about processing speed. I design and program in Fusion 360 then use GRBL to process the G-code and Open Builds CAM to run the program. So many times i have run into problems with the program running very slow and jerky. I've tried both with and without smoothing on. Sometimes it works smoothly, sometimes not. The update we just got appears to have fixed it for now but what else can i do to aid in processing?

    Lasty, since about 3 updates ago, everytime we do an update, Z motion gets inverted but it only pertains to my macros and to probing. Jogging operates normally and come to think of it, if i jog Z after having this problem, it fixes itself.
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    OpenBuildsCONTROL? (CAM converts drawings to GCODE) - its meant more as a beginner, get started Host, try other Grbl hosts like UGS2, CNCJS, bCNC, Candle, etc too
    Troubleshooting tab > Application diagnostics can help with some performance bottlenecks

    RE Limits: More details
    - Wired NO/NC
    - Which switches do you have? Micro, vs Xtension, vs 3rd party
    - What kind of spindle
    - Shielded/unshielded cable
    - Ferrite cores for EMI
     
  3. Blake Barr

    Builder

    Joined:
    Jun 2, 2019
    Messages:
    11
    Likes Received:
    9

    Yes, i'm sorry, Open Builds Control. I have downloaded CNCjs now and i'm working on learning the software. I've been so comfortable with Open Control its a shame i'm having to move to another platform. one thing is for sure, GIThub is a flipping mess to work with.

    stock switches all wired NO. Well, i say stock. The Z isnt the switch the machine came with but is still the "same" thing. I have Ferrite cores on my USB cable and my router power cord. Makita router.
     
  4. Blake Barr

    Builder

    Joined:
    Jun 2, 2019
    Messages:
    11
    Likes Received:
    9
    alright so i just ran the same program in CNCJS and the exact same thing happened. the program ran incredibly smooth as far as toolpaths go so how do i go about determining the fix to this issue? Like i said, i run pretty aggressive programs so possibly the noise is triggering the limit switches?
     
  5. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    Most (good) github projects posts the installers on the Releases tab:
    cncjs/cncjs
    And you might not have to change, but its a good test to see where the issue is

    Upgrade to these bad boys https://openbuildspartstore.com/xtension-limit-switch-kit/ - onboard noise filters (;


    Good! Router cable far away from other cabling?

    Better than a VFD (; - lot less EMI, Xtension Limits by themselves may be the ticket already


    Try the Xtension switches
    Or get some SN-04 Inductive sensors (they are supported on BlackBox too! It has 24v output, and protected inputs you can use SN-04s!) - being Inductive, there are no moving parts :)
     
  6. Blake Barr

    Builder

    Joined:
    Jun 2, 2019
    Messages:
    11
    Likes Received:
    9
    nah, router cable is close to everything but the Ferrite core is right where they are close. I managed to get the program to continue running. Layed the Z axis limit switch wiring a little different and made sure the limit switch wiring was secure. Now that I've got CNCjs running, im already kind of getting used to it. The macros they have available are also very nice. You can speak in a much more advanced language which i like.

    I will certainly look into those switches. They look really close to what I have on the Z axis but mine doesnt have the noise filters. The inductive sensors are also something I am going to look into.

    The goal is to eventually run a 3HP water cooled spindle and most likely use acorn (centroid) but thats a good ways off. a ton more to do
     
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    13,751
    Likes Received:
    4,070
    That might be the issue :)
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice