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g code glitch or is something else ?

Discussion in 'General Talk' started by briho, Apr 14, 2021.

  1. briho

    briho New
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    hi everyone, hope i post this thread where i should be posting, is my first time posting here.
    i`ve been having a problem with the machine, and i don`t know where this problem is coming from, it just runs the g code normal until one point and then the machine goes weird, this is the second time when it happens , and is either goes weird on X and Y axis .. either goes weird on Z axis.
    first time when it happened was about 2 months ago and i was doing the contour of a rectangle and it just went diagonally on X,Y axis for no reason , it wasn`t in the gcode, it didn`t showed on the simulation in fusion 360, i even checked the g code in visual studio code from fusion 360, it wasn`t the first time when i have done that contour, it just did it, so i didn`t pay attention to much on that, now the second time i was carving a 3d ( or a 2.5 ) model and it went weird on Z axis, was about to finish the g code, it had just few more lines until the end, and all the sudden Z axis didn`t go up as it should, just went through material, cut the piece that i was carving, dropped down about 5 mm more than it should, and i think at that point, the blackbox recognized that level as being the 0 plane, and went down another 5 mm or more and now i have a hole in the machine bed frame and a dull bit, both of them happened just before the end of the g code.
    did the update on openbuilds control software just before i stated the job, on both problems if this has anything to do with it
    any info about it would be appreciate it
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    David the swarfer likes this.
  3. briho

    briho New
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    ok, thank you, now it makes sense why i had the alarm triggered for the hard limit when the spindle was in the center of the working area, just one question, if i replace all the cables with shielded ones, will this help me get rid of this problem, at the moment i have only a few of those shielded ones, and ferrite on the ones that are not shielded
     
  4. Alex Chambers

    Alex Chambers Master
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    Best solution is to route the cables that might be a source of emi (mains, spindle/vfd are the main culprits) away from any low voltage stuff. Attach them to your dust extractor hose if you have one - and earth that as static is often the cause of problems. Especially keep potential sources away from your usb lead.
    Alex.
     
  5. briho

    briho New
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    Thank you Alex, i will have a look into that and try to reroute the cables, and i will replace the ones that are not shielded.
     
  6. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Shielding is not always the easiest strategy, what kind of spindle and limit switches do you have?
     
  7. briho

    briho New
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    Huanyang vfd and spindle, the cable from vfd to spindle is shielded. from blackbox to pc is shielded as well. and some other ones
    limit switches . some no name
    but i think i know where the problem is, i have a hole in the table where the cnc is, and i route all the wires through that hole, i mean literally all the wires .. now i have to figure out a way to route them differently
     
  8. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    So right, fixing the SOURCE of the EMI (aka spindle) is going to get you a lot further than trying to shield everything against EMI that should have been arrested at spindle end properly.

    See section 2.8 docs:blackbox:faq-emi [OpenBuilds Documentation] in particular the last point on that section for further reading. Fixing the spindle earthing will sort it all out once and for all. Without having to replace any wiring on the low voltage side. Even if you fix the wire routing, VFD Spindles create a tonne of EMI


    And yes, that is a bad design too.

    Throw the VFD cables on an overhead swing arm:

     
  9. briho

    briho New
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    The earth lead from spindle is connected to the earth end on the vfd but i think this might be the problem .. all the wires in one hole, i will route them differently
    Screenshot_20210415-133959_Gallery.jpg
     

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