Newbie CNC/Laser + 3D printer

  • Hi! Please pardon my newbieness (if there is such a word). I have been trawling through the wiki and forum but have not quite found the info a need. Apologies if I have missed it somewhere...

    I have ordered some parts to build a ooznest ox but without the controller as yet, as I am planning to get a Duet3D. It has 4x Nema 2.8 motors for a dual-Y axis CNC build. My main use will be light CNC and laser (probably max 5W laser diode) and hope to add some 3D printing at a later date, bearing in mind that the current gantry does not allow much travel in the z-axis. It may be that I might build a separate 3D printer, but would like to use the same controller and swap cables etc. I am planning on using Fusion360 for the CNC and 3D and inkscape for the laser generating gCode.

    I am getting confused with the wiring for the laser and CNC and unfortunately, the wiki is not idiot-proof enough for me. As far as the steppers are concerned, my understanding is that X goes to X, Y left to Y, Y right to E0 and Z to Z1, Which leaves E1 free later on for the 3D printer functionality. I am planning to get a 24V 350W PSU initially.


    1. I guess it is not possible to have both Y's wired either serial or parallel?
    2. The wiki on the laser talks about a H1 header? Where is the H1 header? Am I missing something obvious?
    3. How do I control the laser (No. 2) and CNC. I thought I could use E1 as implied by the gcode docs, but is this not the case?
    4. I was thinking of getting a 48V 400W air-cooled spindle for the CNC function - can I still have this running off the high current heated bed output, wired up to a 48V PSU (bearing in mind correct wiring). I am assuming 24V 350W would be sufficient to run a 5 - 8 W diode laser?
    5. If I were to use a 48V PSU for the spindle as above, can I use that to run two 24V heating pads wired in series, as I do not think the 24V 350W PSU will be sufficient to run a 40x30 heating pad (~500W at 0.4W/cm3)

    What I would really like is keep the stepper connectors fixed, and swap out cables easily depending on whether I am using the laser, CNC or 3D printer and switch on the extra power supply accordingly.

    Once again, apologies if this is all covered somewhere...

  • administrators

    1. Yes it is. The two Z motor connectors are wired in series already. So if you have only 1 Z motor, you can connect the Y motors to the Za and Zb outputs, and connect the Z motor to the Y output. Then in config.g near the beginning, put M584 Z1 Y2 to tell the firmware you have done this.

    2. H1 is the Heater 1 output, which is the green terminal block labelled E0. Or you can save that for 3D printing use and use the E1 terminal block instead (Heater 2).

    3. Best way to control the laser is to use latest firmware (2.02RC2), use M452 to put the machine in laser mode, and have your GCode file generator generate S parameters on the G1 commands to control the laser power. There are at least two programs that can do this.

    4. The bed heater circuit includes a capacitor rated at 35V (the one actually fitted may actually be rated higher than that, I would need to check) and a mosfet rated at 40V. So 48V is too high. Even if using a lower voltage, you would need to connect a flyback diode in parallel with the spindle motor.

    5. For a 400W bed heater, consider using an AC mains voltage silicone heater controlled by a DC-AC SSR. This is straightforward if the bed is fixed. Series-connected PSUs may do strange things if the output is shorted or overloaded.

    There is probably no need to switch cables around to change modes, because you can also drive external heaters and spindle motors using SSRs connected to the expansion connector. You might want to add a laser isolation switch to make sure it can't be turned on in CNC and FDM modes.

    HTH David

  • Thank you. My parts should be arriving today and assuming all is well, I shall be ordering the duet3D soon...

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