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IndustryArena Forum > Other Machines > PCB milling > Advice needed to create isolation paths
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  1. #1
    Join Date
    May 2011
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    0

    Advice needed to create isolation paths

    Hi guys,

    I've been trying to use various software KCam, mach 3 and so on with my machine and I get unreliable performance each time, either code won't import, line will be missing etc....

    So I've decided to write a program of my own to be a one-click solution from importing a Gerber pcb file to driving a CNC machine controller.

    So far I have prototyped the code in VB ex2008 to import the gerber file and display the tracks and pads on screen. I've been able to create the rough outlines of every track and pad.

    My problem is how do I connect each of the individual outlines to it's neighbour without getting intersections where there shouldn't be?

    What is the best way to solve the problem? did I calculate each intersection or did do I solve it graphically? Calc each intersection can have issues when a power plane is made of lines as an outline would be established for each line.
    I think solving graphically would be the better way by first drawing the whole gerber layout and raster scanning in the x axis for edges of tracks/pads, and then scanning in the Y axis for edges again. Therefore build up a list of coord of edges and then organise those epoint into paths. Seems more intense.

    Once I have the outline in a vector of X & Y co-ords, I can easily pipe the co-ordinates down a serial port to a seperate interpreter card bolted onto a standard stepper motor controller. The interpreter can handle the interpolation between the 2 coords.

    Any advice would be welcome.

    BR
    Adam

  2. #2
    Join Date
    Dec 2010
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    0
    sorry to send you in a completely different direction, but have you tried EAGLE for designing the PCB - there is a plug-in pcb-gcode that spits out gcode to do exactly what you're looking for

    for smallish boards EAGLE is free

  3. #3
    Join Date
    May 2011
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    0
    Hi mmcp42,

    Yeah I thought ofthat, briefly. Only problem is I have loads of PCB designs in Proteus, which allows me to simulate code in PIC designs, so I'm likely to stay with it.

    besides, if I can find a way of doing what I'm after in the first post, I'm sure it should work for lots of other ppl too, regardless of theier PCB CAD package.

    I've also used toyed with CopperCAM,itsok for simepl designs, but as soon as you have copper planes made of lines it goes do-lally. I'd still need a CNCdriver package.

  4. #4
    Join Date
    Dec 2004
    Posts
    1137
    Quote Originally Posted by motorman78 View Post
    Hi guys,

    I've been able to create the rough outlines of every track and pad.

    My problem is how do I connect each of the individual outlines to it's neighbour without getting intersections where there shouldn't be?
    I am trying to understand if you mean that what should you do when you complete one "outline" (I call them paths) to move the tool to the start of the next path?

    If so. then you need to raise the Z, add the G1 command to the move the tool to the next X,Y coordinate, then lower the Z back to your cutting depth and continue your XY moves.

    Or did I miss the question?

    Even if you don't use Eagle, the PCB-gcode plugin script might offer some inspiration.

    -Jay

  5. #5
    Join Date
    May 2011
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    0
    Hi Jay,

    plz see the attachement.

    I can open the gerber file and display what's in fig 1.

    I can work out the tool path of each primitive object by drawing the outline with a offset (fig 2, red lines)

    What I need to understand is, what is the process/algorithm/whatever that I need to do to connect the outlines in fig 2 to make the continous toolpath in fig 3.

    This is what I can't get my head around ATM.
    Should I try somesort of mathematical solution (which isn't trivial) or do a brute force raster scan in the X axis, then the Y axis and build the path by finding all contigiuos point?

    Not sure where to go from here...
    Attached Thumbnails Attached Thumbnails PCB routing.bmp  

  6. #6
    Join Date
    Dec 2010
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    0
    what you are doing is mimicing what running the pcb-gcode script does to an EAGLE file

    suggest you take a look at that script as it is doing exactly what you want, albeit to a different file format

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