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How to use the Modela MDX 20

We have the Modela MDX-20 3D milling machine in the lab. We use mods to operate the machine. The copper plates (fr1) we use have pressed paper in between; we don’t mill fr4 (with glass in between) because it ruins your machine (dulls the bit very quickly) and it’s dangerous to have glass dust (to breathe it in or get it in your eyes). The Modela has a .006mm precision (in theory).

Steps

  1. Turn the Modela on. The machine automatically goes to machine home, it’s in view mode (can turn that off with the view mode button). If there’s not enough room on the copper plate or there is no copper plate on the sacrificial layer, add a new one. Remove the bed with the screws on the side, then press the board tightly and perfectly flat with some clean fabric on the bottom to protect against scratches, and the acrylic on the top to apply pressure. Stick the copper plate to the bed with double sided tape (clean surfaces first with sticker remover); completely fill it up but don’t let the tape overlap, otherwise it’s not level
  2. Now replace the milling bit if it’s not the correct one. You can’t release it and let it fall out because it will break; hold one finger against the milling bit and take it out in a controlled way. For traces we use .4mm milling bits (one or two flute)

    Roland Modela Roland Modela

  3. The .4mm milling bits we use can be a one or a two flute. Make sure to put them back in the correct place in the box after use

  4. Put the milling bit in all the way up, so it’s sticking out a little bit still but won’t touch the copper plate when the Z axis is moved all the way down
  5. Start mods (type cd mods followed by bash mods in the terminal) to fire up a serial server connected to the Modela. Chromium is going to open automatically. Right click and select MDX Mill > PCB

    Roland Modela Roland Modela

  6. Close WebSocket pyserial, close the pyserial port, then close socket and port for the WebSocket serial, then open socket and open port there. Try moving to the origin to check if there’s a connection

    Roland Modela

  7. Move the machine to the left bottom corner (when looked at the machine from above) where you want to start milling; do this by changing the origin value in mods and clicking Move to origin. Write down the X and Y value. Then go all the way down with the machine with the buttons on the machine (not in mods) and then move it little bit higher. You can only do this when the milling bit is all the way up. The bit is floating above the material. Now we can lower the bit with support of two fingers to touch the material (the actual material, not the sacrificial layer); wiggle it in case there’s dust so it’s resting perfectly on the material and then secure it. Tighten it snugly, not aggressively. The machine is now ready to mill

    • If you move the origin, you also have to redo the Z axis alignment. This has to do with the imperfections of the board; it does remember where the 0 point was but just to have it as precise as possible you have to redo it

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  8. Now you start with the traces in mods (PNG or SVG); one image at the time. White is the area you want to keep. When using a PNG don’t forget to put DPI as 1000; if you have issues with not all of the traces being translated to proper traces, you can play around with the image threshold.

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    Select the PCB defaults in mm, mill traces (1/64"). Roland Modela

  9. Settings for milling traces:

    • Tool diameter is 0.4mm
    • Cut depth and max depth is 0.002 inch (numbers from experience); this will cut through the top copper layer. If you want to mill deeper, lower the speed
    • Offset number is the (maximum) amount of traces from the lines you want to keep. 4 is nice, it makes it easy to solder and doesn’t take forever. 0 mills away everything except the traces
    • Offset stepover: half of the tool diameter
    • Direction: just leave at climb, it doesn’t really matter
    • Path merge is 1 (diameter of the tool)
    • Path order forward/reverse: Just use forward
    • Sort distance: checked
    • Cut speed 4mm/s for this milling bit (for the one flute, for the two flute 3mm/s is probably better)

    Roland Modela Roland Modela

  10. Press Calculate

  11. Web socket serial > send file and it will start milling straight away
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  12. When it’s milling, keep an eye out for whether it’s milling all the way through the copper layer. If it’s not you’ll usually see that there’s not a lot of dust and/or you still see copper where the mill has already been. If it’s not going through, you can pause by pressing the view button on the machine, and double check. To stop the job (not just pause it), you have to press the UP and DOWN for 10 seconds. The flashing lights indicate the memory is being erased. When it’s done, the lights stop blinking. Then adjust the Z axis and start the job again
  13. When it’s done vacuum the dust and check if everything was milled properly
    Roland Modela Roland Modela
  14. Now for the cut-out you need your other file and the .8mm milling bit. Repeat the steps above. Speed is 4mm/s again, cut depth is 1,55 (or more depending on the thickness of the specific copper plate) and .6mm per layer cut depth

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  15. Take the PCB out with with a small screwdriver

  16. When the lines are rough you can sand them with regular printing paper

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  17. If you didn’t clear out the entire board, make sure to clear out the USB traces

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