Milling PCBs?

Discussion in 'General Electronics Chat' started by spinnaker, Dec 20, 2015.

  1. spinnaker

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    In this thread regarding my search for a drill press, Mitch suggested a CNC320 as a solution. At first I thought wow $400+ is a whole lot of money to invest in the few PCBs that I make. Then I thought again, Not like I have several expensive toys that I could probably really don't need but enjoy. What is one other? I can afford it. Drilling is the worst part of the project for me since my hands are not all that steady and my hand eye coordination is not the greatest. It won't get any better as I get older. I might as well invest the money for a good drill and press into a CNC tool

    I have some questions.

    1. I have seen a video of the CNC320 milling a PCB. The edges at least appeared a little ragged. Is that normal for milled PCBs?

    2. Are there special bits I will need?

    3. Should software come with the CNC machine? Will it stop and tell me to change bits for holes and such?

    4. I noticed the CNC320 requires a special adapter card for the PC. Is this normal or do some use USB connection?

    5. Other than cost, noise and excess dust, any down side to a CNC?
     
  2. GopherT

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    The trace width has some minimum (as with all methods) and you have to inspect your finished product very carefully because some of your chips and turnings (debris) can be melted/welded to the board and bridge traces. Then you have to run a knife blade between the traces to break them loose.


    As for the board to connect them, generally your pcb files are converted to G-Code and code drives the machine (and most every other computer controlled manufacturing machine). There are Arduino boards that can be used (as an interface between computer and machine, or, the arduino can act as the stand-alone controller of the machine if you have an SD card reader. It really depends on how integrated or barebones the CNC machine is (and where you can tap into the electronics.
     
  3. nerdegutta

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    For what I've seen on youtube about the CMC 3020. It's communicating on the parallel port and the software is LinuxCNC.

    I've used LinuxCNC, and it is fairly easy to configure and setup.
     
  4. spinnaker

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    How thin of a trace can I go? Will toner transfer method let me go smaller? If not, I am not really concerned.
     
  5. spinnaker

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    Does the software stop as ask you to change bits? Are there windows versions?


    Do you use a CNC for PCBs? What do you use? Are you happy with the results?
     
  6. nerdegutta

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    Yes, it stop tell to change bits. That's in the G-Code.
    There is no Windows version of LinuxCNC, but I think MACH3, does the same.
    I've not milled PCB's yet. My CNC machine is home made, and I've not found a proper drill bit to fit my chuck to use on PCB.
     
  7. spinnaker

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    Yes the Ebay listing mentions Mach3. I sent a message to the seller asking which version of Mach3 I need. I am also going to ask about the bits. I hope the ones I have at least work for the holes. Thanks for the head up on that.

    Do you need special bits for the engraving part?
     
  8. nerdegutta

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  9. ISB123

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    CNC Bits are generally shorter so they don't snap while milling.
     
  10. Wendy

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    I am following this thread with great interest. They have several machines at Dallas Maker Space I want to learn how to use.
     
  11. atferrari

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    Time ago I was posing those questions myself.

    I posted them here

    I got around 10 answers. I failed to buy that machine by the way, albeit still interested.
     
  12. Dr.killjoy

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    The machine looks pretty from what the pics show but my main concern would be the round out of the spindle.. Cause your relying on the motor bearings to keep the spindle straight and that's alot of force placed on those bearing from a distance.
     
  13. KeepItSimpleStupid

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    Last edited: Dec 20, 2015
  14. MaxHeadRoom

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    I have no experience with the CNC3020 but there is a review here that indicates the run out etc, when using a motor as a spindle instead of driving an actual spindle itself, the design of the bearings have to be of a certain type to prevent excess run out.
    There is Mach3 that runs it through the PP. currently there is also a Mach4 version being developed, the S/W is free for up to a certain size of program.
    In a CNC for tool change a T1, T2 etc command is given, in the case of an auto changer, the machine does it automatically of course, with a manual change the program stops at a T function and after the tool or bit is changed the Cycle start button is pushed to carry on.
    Evidentally there is a unpublished option on the board for PWM control of the spindle via Mach3 etc.
    www.essentialscrap.com/cnc/first_impression.html

    Max.
     
  15. spinnaker

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    Thanks Max. Looks like that review is basically the same to others I have seen. Pretty much a great CNC for it's price range. A .01mm runout is pretty much what the proxxon rotary tool was measur
    ed.
    Are you sure the Mach4 software is free? I went to their site and there appears to be a cost. They have prices all over the place and I have not yet nailed down what is what.

    Other costs I have discovered (prices in US)

    Etching bit ~$30
    Alignment Pins ~$130 (I am trying to determine if they are really needed).
    Aluminum plate to mount the PCB while etching. Cost unknown.
     
  16. MaxHeadRoom

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    Maybe they are charging now?, AFAIK Mach3 is still free up to a certain pgm size.
    I also see there is a ballscrew version of the CNC3020 for another $300.
    Max.
     
  17. spinnaker

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    This thread mentions health issues with fiberglass dust when milling PCBs. Something to consider even when drilling.
     
  18. MaxHeadRoom

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    These are the present restrictions on the Mach3 demo version, no limit on time.
    • Mill & Plasma: 500 line gcode limit (10,000,000 limit after licensing)
    • Turn: 50 line gcode limit (10,000,000 limit after licensing)
    • Kernel Frequency locked at 25kHz (only applicable if using the parallel port driver)
    • Set Next Line function disabled
    • Run From Here function disabled
    • Turn: Threading disabled
    • Plasma: THC functions disabled
    Max.
     
  19. spinnaker

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    How does that stack up to a board most hobbyists would turn out?
     
  20. MaxHeadRoom

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    500 lines is quite a bit of code, a way around it is to split the program up into 2 or 3 separate ones etc.!;)
    Max.
     
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