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IndustryArena Forum > MetalWorking Machines > EMCO CNC Machines > EMCO Mills > Emco F3 conversion - electronics and controller
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  1. #1
    Join Date
    Mar 2012

    Emco F3 conversion - electronics and controller

    This is a supplementary thread to the others detailing the conversion of my Emco F3 mill, in which I will detail the changes to the electronics and some considerations for selecting a controller.
    The original electronics are switch gear that are typical of the period: good quality equipment but very 1980's in execution. The power supply is 3 phase 400V AC, and interesting has no neutral wire, read on. Power to the main motor is controlled via a two speed dahlander switch which allows the motor windings to be connected as delta or star to vary the speed.
    Supply to the existing X Axis power feed (the only one originally fitted) is via a transformer and the variable speed is handled by some crusty looking electronics on a board in the control box.
    The coolant pump is a 3 phase motor and has a simple 3 pole switch.
    The DRO is an obscure brand (Aurki) and requires 230VAC. This is supplied by one phase and connecting the DRO's neutral wire to the mill's protective earth - thus relying on the tie between the neutral and earth at the building's electrical installation to carry the return current. IMO, this is not a particularly safe way of doing it but I'll be ditching the DRO once I have the CNC conversion completed so it stays at this point in time.

    The manual controls are placed on a sloped panel facing the operator - this panel sits atop the control box which is a fabricated steel cabinet bolted to the rear of the machine column. Dimensions are roughly 500H x 250W x 190 D, with the control panel protruding another 195mm.
    Click image for larger version. 

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    The slightly later F3B model changed the shape of the control box - it does not slope back under the operator panel - and I think a design similar to this could provide additional internal capacity for the gear that needs to be installed.
    Click image for larger version. 

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    There is sufficient room to make the box 50mm wider (although I'd like to reuse the door), or make it deeper.
    Attached Thumbnails Attached Thumbnails Screenshot from 2022-01-10 18-58-27.png  

  2. #2
    Join Date
    Mar 2012

    Re: Emco F3 conversion - electronics and controller

    I'm also keen to retain some elements of a manual mill, i.e. be able to switch the spindle on at slow or high speed, and move the X/Y/Z axis manually in a variable spped jog mode (including rapid).
    I've mocked up a layout of a replacement front panel in CAD, here's the first iteration. I've made this so it is the same dimensions as the existing operator panel.
    Click image for larger version. 

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    The Ready and Fault are indicators only (not switches)

  3. #3
    Join Date
    Mar 2012

    Re: Emco F3 conversion - electronics and controller

    I'm leaning towards a Eding CNC 720 board. The vendor has been responsive to my questions and it comes complete with decent software, connects via Ethernet, mounts onto a DIN rail, is 24V compatible, supports E Stop inputs, 2 coolant outputs etc etc.
    I already have CL86T closed loop drivers from OMC Steppers online. These will be mounted to a hinged backplane.
    The other items are the power supply for the motors (3 phase 400VAC to 48VDC, 960W), power supply for the controls, spindle motor switching contactors and protection, a disconnect relay for the E Stop button, relays for the flood/mist/light main supply breaker etc.
    All in all quite a bit to fit into the box. I'll need to do some layouts to check it fits within the existing enclosure, or I can get a sheet metal fabricator to fold up the parts for a larger unit that will fit in a similar place to the original Emco item.

  4. #4
    Join Date
    Mar 2012

    Re: Emco F3 conversion - electronics and controller

    OK, have done a little planning for the equipment that needs to be accommodated in the control box:
    1 x 3 phase MCB
    1 x 3 phase 400VAC coil (main contactor)
    48V 960W 3 phase PSU (for stepper motors)
    24V 240W 3 phase PSU (for general controls)
    1x contactor for stepper motor PSU and spindle (E stop)
    3 x contactors for spindle (dahlander control)
    1x contactor for pump
    1x contactor for mist
    4x stepper drivers
    1 x DIN rail mount EdingCNC 720 controller board with BoB
    1 x DIN rail mount Eding UIO-10 auxillary board
    various switchgear for manual/CNC controls
    2x fans for coolimg

    I've done a rough layout and will design a control box 100mm deeper than the existing.

  5. #5
    Join Date
    Mar 2012

    Re: Emco F3 conversion - electronics and controller

    I've drawn up a prelim design for the control box. This follows the shape and form of the existing one, however it is 50mm wider, 100 deeper and 30m shorter.

    The additional depth was required to fit the components and allow some room for a future fourth axis. I made it 30mm less tall so I can use the two M8 threaded holes in the back of the column to attach the reconfigured Y axis motor mounting plate. As this meant the existing door could not be used I made the enclosure 50mm wider to provided better airflow for cooling.

    I have sent the drawings out for a quote from a local sheet metal fab shop. The box will be TIG tacked on the joints and then silver soldered along the seams.
    Attached Files Attached Files

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