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CNC Operation with mind of its own? RIP Endmill :(

Discussion in 'Controller Boards' started by ThumbNailer, Oct 14, 2018.

  1. ThumbNailer

    Builder

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    Hi Guys

    My Workbee seems to have developed a mind of its own?!

    Let me explain: I got the Workbee last Christmas and had a ton of fun with it since. Never any big issues. But now on my pending project, the Workbee decided to go off course mid operation!?

    First my specs: WorkBee 750x750 mm screw driven / Makita RT0700CX2J / VCarve Desktop v9.5 / Universal Gcode Sender V2.0 / xPro V3 Controller.

    The operation specs: Birch Plywood 20 mm / Drill Kyocera 1/8" Carbide 3 Flute / 30'000 RPM / Feed Rate 40 mm/sec / Pass Depth 3 mm.

    My current project contains rather long operations (2-3 hours), cutting out a lot of equal pieces. What happend: Mid operation it did the last pass of an 2D Profile Toolpath on the bottom (the one with the tabs to fix the piece) as the first pass of the next piece on the top!? Then went back to the last piece an cut through the spoiler board. Which broke the drill (RIP!).

    So I thought, ok, can happen, I reset everything an finished the operation, with no problem.
    New job: 15 min in to the job (pocketing) at some point the machine started cutting not the programmed 3 mm but about 6 mm per pass. When I wanted to reset the job, I realised that Zero was completely off, making it impossible to restart the job, because I would not be able to find the same Zero again.

    Thats where I'm now... can any of you give me a hint what could cause such a problem?

    The only parameter I changed right before the issue is the feed rate and pass depth. Up until now, I used somewhat like 25 mm/sec feedrate and 1.5 mm pass depth (for birch plywood), but that takes forever to cut, besides I think my router and drill bit should be able to handle more than that. Besides that, why would these parameter interfere with the operation??

    I Attached the second gcode file, which failed on the second pocket operation.

    Thx a lot for any Hints and Tips!

    Regards from Switzerland - Marcel
     

    Attached Files:

  2. GrayUK

    GrayUK Openbuilds Team Elder
    Staff Member Moderator Builder

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    That sounds a lot like a mechanical thing. :rolleyes:
    GCode isn't going to send it through the Baseboard unless you have told it to.
    Have you checked grub screws and the like?
    Do an Air cut and see what happens. :)
    See if there are any common events.
     
  3. ThumbNailer

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    Thx for your input Gray.

    But why would it start the profile toolpath with the pockets? I attached an image with the explained situation. If a screw would be loose, the Z axis would be off for a bit (for example). But my situation is weird... as if it took a complete pass an moved it up the list!?

    Marcel
     

    Attached Files:

  4. David the swarfer

    David the swarfer OpenBuilds Team
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    Check your USB cable, this might be a symptom of bad communication resulting in some code not being received by the controller.

    Also, run your Gcode through a simulator like NC Corrector, free G-Code editor. or CAMotics
    nc corrector will detect errors in the Gcode and display a wireframe view of the cut, you can rewind it and then step through it line by line.
    camotics will display the actual cut in the material but will happily ignore any gcode errors

    I have just run your code through both of them and cannot see any obvious problems in a quick look.

    I do notice that your hole drilling operations are doing straight down plunges for each layer. Endmills are really quite bad at doing that, they are not drills so if your software can instead generate a 'spiral bore' or some sort of ramped or helical entry that would be much better. The straight plunge can easily cause the flutes to pack full of chips, which in turn hugely increases the cutting forces which may be causing lost steps.
     
  5. David the swarfer

    David the swarfer OpenBuilds Team
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