PCB Milling

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  1. Design board with Eagle
    1. Draw schmatic and layout of the board
    2. In the Eagle .brd file, create the SAME board boundaries in lays "Top", "Bottom" and "Milling" with ZERO-width wires (to do: an example picture)
    3. Also create two horizontal positioning holes (drill diameter=0.125984in)with EAQUAL distance to the left/right edge of the board ( to do : picture)
  2. Generate Garber codes with Eagle
    1. Open File => CAM Procesor for CAM setting dialog
    2. Open File => Open => Job ..., choose double_side_board.cam
    3. Press button "Process job" and answer "OK" for all popup dialogboxes to generate 7 CAM files under the same directory with the .brd file:
      1. top.cmp, bottom.sol : the Gerber files for the board traces
      2. top_cream.eps, bottom_cream.eps : the eps files for the surface mounting cream masks,which will be loaded in Adobe Illustrator
      3. drills.drd : describing the drills for vias and pads
      4. holes.drd : describing the through-holes and positioning holes
      5. cutting.cmp: describing the boundary of the board and used to cut it out of the whole copper board
  3. Positioning Mill
    1. choose the origin ( bottom-left corner of the design ) on the copper board. NOTE: the position should be carefully chose so that the copper board should be able to fit in the mill when the bottom layer is milled !!!! )
    2. use "type move.rml > com1" to set the actuall origin of the board as (mil_X,mil_Y)in mill-coordinate
    3. Set Z reference point
  4. Generate MDX command scripts from cmp files
    1. Start phthon: IDLE( Python GUI)
    2. Open cam_v06_fixed.py
    3. Run => Run Module or F5 to launch the main converter program
    4. Press "input file" to load the top layer Gerber file top.cmp file
    5. MUST Press "Scale:Fixed"
    6. Write down the two numbers (in inch)appearing at "x min" and "y min" as (eag_x,eag_y), which are the origin of the layout in Eagle-coordinate
    7. Calculate the coordinate offset: offset_x = mil_X - eag_x, offset_y = mil_Y - eag_y;
    8. Add the offset_x/y to the existing "x/y min". Of course,for top.cmp, the result is mil_X/Y, the actual origin in the mill-cordinate
    9. Select the mill to use in "output device" list. Here we choose "rml: Roland Modela NC mill"
    10. Set "output file", for instance "top.rml"
    11. Set "z down" = -0.005 ( 5 mil deep )
    12. Set "xy speed" = 1
    13. Set "z speed" = 4
    14. Set "tool diameter" = 0.01 ( 10 mil )
    15. Adjust "undercut" to ensure isolation, but the smaller ( negative), the better
    16. Press "contour boundary" to show the tool route to generate". If the isolation is not enough, adjust the "undercut"
    17. Press "raster interior"
    18. Press "write tool path"
  5. Generate Gerber code for bottom.sol
    1. first use "scale:fixed"
    2. add offset_x and offset_y to the resultant numbers in "x/y min"
    3. use "z depth=-0.005", "xy speed = 1" and "Tool diameter = 0.010"
    4. use "raster interior"
  6. Generate Gerber code for drills, holes and final cutting
    1. Load drills.drd, holes.drd and cutting.cmp
    2. add offset_x and offset_y to the resultant numbers in "x/y min"
    3. use "z depth = -0.08" and "Tool diameter = 0.03125"
    4. NO need for "raster interior" for the drd files and definitely NO "raster interior" for cutting.cmp !
  7. Start milling
    1. mill the top layer by using "top.rml"
    2. change mill to 0.03125 endmill bit
    3. set z-reference point roughly
    4. drill for vias and pads by using "drll.rml"
    5. drill for through holes with "holes.rml"
    6. use 1.259in mill bit to manually deepen the two positioning holes
    7. flip the board horizontally and fit in the position holes
    8. change mill to 0.01 bit
    9. precisely set z-reference point
    10. mill the bottom layer "bottom.rml"
    11. change mill to 0.03125 endmill bit
    12. cutting the board out "cutting.rml"
  8. Important:How to stop milling during sessions
    1. Delete the printing job from the Roland MODELA print queue
    2. Set the mill in "view" mode
    3. Press the "up" and "down" buttons simultaneously, and then the "view" LED will flash
    4. Wait until the "view" LED stops flashing, when the milling data has been removed from the mill