CNC Plasma build

  1. MattH

    MattH Member

    Messages:
    3,579
    Location:
    Bristol
    I’m currently in the process of converting one of our 8x4 routers into a plasma table.

    The build will consist of:

    • Tekcel CNC table retro fitted with 400w AC servos
    • Hypertherm Powermax 45xp
    • PriceCNC THC
    • Mach3 with Ethernet smoothstepper
    The table and existing controller and motors have been removed from the table (these will be spares for our other two Tekcel routers):

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    Old 250w brushed DC servos next to the new 400w brushless AC servos:
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    eSCHEn likes this.
  2. MattH

    MattH Member

    Messages:
    3,579
    Location:
    Bristol
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  3. pressbrake1

    pressbrake1 Member

    Messages:
    1,323
    essex england
    Dc servos used to drive me nuts back in the nineties!
     
  4. MattH

    MattH Member

    Messages:
    3,579
    Location:
    Bristol
    To be fair the Tekmov controller in the Tekcel routers works very well, but it’s a closed system so it’s easier for me to rip it all out and replace it with standard parts.
    AC brushless servos have so much more torque and speed.

    I have a set of DMM Dyn2 drivers and motors that I’m hoping to use, these were left over from a router project and they got replaced with Leadshine EL5 units.

    The DMM drivers have no opto isolated IO and are fairly basic. I’m just waiting on some HCPL2631 optos to arrived to test the integration with my 24v Controller IO.

    If they prove to be no good I will use a set of Leadshine EL5’s that I have on the shelf which has industry standard IO and are much easier to interface too.

    Here’s what got removed to make way for the new electronics:

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    julianthegypsy likes this.
  5. MattH

    MattH Member

    Messages:
    3,579
    Location:
    Bristol
    Crazy busy with pre-Christmas orders at the moment so haven't progressed this much.
    The idea is to work on it over the Christmas holiday so we can be cutting in the new year.

    My opto isolators arrived so I could test the DMM servos with the ESS and MB2 board. The cheapo opto-board I'd grabbed wouldn't cut it as the rise time was only 18us and the pulse train is 5us.
    The HCPL2631's have a rise time of 50ns so plenty fast enough.
    I mocked it up on a breadboard and confirmed they worked while and then designed a quick PCB for all of them.
    Just waiting on he PCB's to show then I can build all the electronics into the enclosure on the machine.

    Now I know which servos I am using the next step will be to re-make the motor mounts to take the bigger servos.

    2019-11-11 12.16.00.jpg 2019-11-11 12.16.09.jpg pcb.png
     
    pressbrake1 and eSCHEn like this.
  6. bletchmonster

    bletchmonster Member

    Messages:
    404
    Location:
    Cheshire. England.
    :( This thread is hastening my journey to the terminally bewildered!
    I've wanted to build a cnc plasma for a long time but reading the above information makes me think I would be better just buying a turn key machine. :laughing:
     
  7. MattH

    MattH Member

    Messages:
    3,579
    Location:
    Bristol
    Not to put you off but building any cnc from scratch even a basic little stepper machine, takes hundreds of hours of reading and research.

    I've built a few different CNC's over the years based on a number of different controllers and hardware. Even with that background I've probably put 30-40 hours of reading in on this project so far.
    That includes researching THC controllers, interfacing with the Plasma power source, floating Z or Ohmic sensing, differential interfacing to the servo drives, refreshing myself on tuning the servo drives, Plasma screensets for Mach3, postprocessors for Sheetcam etc etc.

    The list goes on and on.
     
    bletchmonster, garethp and Shox Dr like this.
  8. MattH

    MattH Member

    Messages:
    3,579
    Location:
    Bristol
    PCB’s arrived from China today.

    Very pleased with them and the service. £10.95 for 5 boards made and delivered within 7 days.

    AD9FBE87-252C-4535-8E47-FBABAF9EB4AF.jpeg
     
    Seadog, eSCHEn and galooph like this.
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