Laser control and future project

  • I admit, I spent maybe five minutes (if that) looking into laser control with the duet boards.

    I expect this to be relevant:

    But before I get too ahead of myself, I am looking to buy this kit (most likely, or build my own)

    Which they claim will do half inch acrylic....which is an 80W CO2 laser which sounds epic. (I know, I'm captain overkill, just wait)

    While I was reading about the pwm laser control, people said that they hooked them up to hot end heaters, which my hot end heaters have a laser engraved 40-60W and 24v written on them.

    This would make sense to me then that hot end heaters could be used for these types of lasers controllers.

    ........what about something bigger? Like....way bigger?

    Bear with me here.

    The DMG Mori makes a Lasertec CNC mill with an additive manufacturing laser metal deposition tool head.

    It is "Available with a high-precision Nd:YAG-Laser 300 W / 500 W or 4 - 30.8 hp. QCW-fiber laser."

    So to me, that sounds like an SSR PWM controlled bed/chamber heater that must be used for that.

    Demo here:

    In theory, if switched between different "printer" or machine modes and by configuring the tools correctly, is it possible to replicate a machine similar to this. A machine such as this is why I prefer three-phase DC motors (or AC) over stepper motors (mainly the torque more than anything else). Inert gas and power can be most likely controlled by pwm fan/pump headers and one for a cooling water pump for the laser system unless an external unit is used and can be controlled by a PWM input (output from the duet).

    I'm getting 0.45° Nema 23 steppers in the mail probably by February, I think I may try to replicate this.

    I'm trying to think of reasons why this wouldn't should be possible, shouldn't it? The slicing/tool path generation issue ignored for right now, my main curiosity is about the hardware because I expect of the hardware can support it, the firmware could (if not now then eventually could be programmed and implemented).

    Thank you in advance, Happy Thanksgiving (is that just an American holiday?? Oh well) thank you.

    This is overkill, I know, but for the most part...a CNC controller is a CNC controller, right?

  • administrators

    Most lasers for these applications have a TTL-level PWM input. To drive such inputs:

    • If your system includes a DueX or a Duet External Stepper Driver Breakout Board, connect the laser PWM input to one of the servo outputs.
    • Otherwise we recommend using a 74HCT02 gate fed from +5V power to gate one of the expansion connector heater outputs with the +3.3V, and feed the output of the gate to the laser PWM input. The gate changes the signal from active low to active high, and gating it with +3.3V ensures that if the 3.3V rail gets shorted to ground, the laser will not be turned on.


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