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problem with outside cuts

Discussion in 'SketchUcam Help' started by Ringo Davis, Sep 26, 2018.

  1. Ringo Davis

    Ringo Davis Member

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    in my file I have a octogon'ish shaped object with an outside cut done with multipass.
    in the gcode viewer it looks fine. But when I open the file with CNCjs the outside cut is shifted off to 1 side in the 2nd pass. And both passes are circles, not straight lines.
    The round part above it was doing it but I redrew it and it works now. Any idea what is wrong with this part?
     

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  2. swarfer

    swarfer Moderator Staff Member

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    firstly your octagon shape is in fact a circle (sketchup 'arc' with a radius and number of segments of 7). if you actually want a septagon, then you need to 'explode curve' the circle or draw a polygon in the first place. then when you add cutlines they will be straight lines as you expect/want.

    the round part has the problem that it is also a multisegment circle (this is all sketchup can do) and one of the segments is cut short in such a way that the gcode generated confuses CNCjs (and NCcorrector) but not gplot. Gcode arcs are tricky things and the math can get confused very easily.

    What I just tried is to select the outside of that circle, right click, show Entity info, then set the number of segments to 96, then I 'explode curve'.
    This makes it into about 96 straight segments that are too short to see in the final cut (well, 6mm long in this case). The bigger your radius the more segments you need to use to make it visibly 'circular', just use a multiple of 12 for best effect.

    my changes in the attached file...
     

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  3. swarfer

    swarfer Moderator Staff Member

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    so, did it work?
     

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