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Sketchucam G-Code not generating corectly

Discussion in 'CAM' started by gareth harvey, Jun 2, 2017.

  1. gareth harvey

    gareth harvey Well-Known
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    Having some massive issues with Sketchucam. I have a drawing in Sketchup, have generated the g-code, have plotted the G-code and viewed it. It all looks good. Sent it over to the CNC and it's cutting circles that are not on the drawing.

    The image is correct in Sketchup and the G-code viewer within sketchup, but different when I click Visualise.

    Is this an error with Sketchucam?
     

    Attached Files:

  2. David the swarfer

    David the swarfer OpenBuilds Team
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    Hi
    A quick fix might be...
    Remove that inside cut
    Select all of the outline
    Right click the selection
    Select 'explode'
    Add a new inside cut.

    But I would like to see the original sketchup file please, just to make sure you have not discovered a bug.
     
  3. gareth harvey

    gareth harvey Well-Known
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    Here are the files, didn't realise these were more important
     

    Attached Files:

  4. David the swarfer

    David the swarfer OpenBuilds Team
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    HI
    It looks like those imported arcs (the entire drawing is arcs except for a few short straight segments) are doing something weird and Sketchup cannot determine the direction correctly. (and Sketchup tells SketchUcam what the direction is)

    To fix it, select each problematic arc in turn (the 2 on the left and the one at bottom right), double the number of segments, then 'explode curve'. When you insert the inside cut you will now get the correct cuts since the problem arcs are now line segments. By doubling the number of segments the segment length is made smaller so the line segmentation should not be visible in the cut since they are smaller than the bit radius.
     
  5. gareth harvey

    gareth harvey Well-Known
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    Thanks, that's fixed it
     
  6. David the swarfer

    David the swarfer OpenBuilds Team
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    wasn't really a problem for me, but then, I am using the new version of Gplot (-:
    panning rate IS proportional to the drawing size, and I need to look at solving that. it should rather be proportional to screen size and maybe zoom level.
     
  7. Sprags

    Sprags Veteran
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    Since you say its not generating g-code correctly i take it you already verified that all of the I, J vector values are correct.

    If you are saying that because you assume the code has not been generated correctly because the tool is not moving as it should based on your drawing then that is completely different. If your vector values were rounded off incorrectly it could cause the machine motion to over travel. I have seen that on commercial CNC machines.

    I'd suggest creating geometry with curves tangent to curves based on real radii or diameters and not based on how the CAM software or the controller software is interpreting spline curves to verify what the real issue is. I'm new to the type of software you are using but I do know CNC programming using real CAM software like MasterCAM and Siemens NX. Those softwares allow you to post process the toolpath motion into G and M code. You can also just write G-code by hand and try it out.
     
  8. David the swarfer

    David the swarfer OpenBuilds Team
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    This was already solved. His drawing had reversed curves in it. Basically having a clockwise curve tagged as anticlockwise by Sketchup.
     

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