Solidoodle? and K40 laser cutter

  • Has anyone used a Duet board for a solidoodle? I have one, and have never been sure of the board and how to upgrade its firmware. When solidoodle still existed their web site had conflicting docs on the update. Id like to simply throw out all its electronics and put in a board I understand, and have good docs and support. It looks like it ought to be simple, but if someone already has a config file that would be easier.

    I also have a K40 laser cutter and intend to replace its board. I was considering a smoothie, but if I can use a duet on it it would be great to have both of my machines on the same board.

    I also have a couple larger mills and lathes running Mach4, which I am quite happy with and will not be changing.

  • administrators

    I have no experience of the Solidoodle, but if you can provide details of the motors, endstop switches etc. then I'll do my best to help.

    I'd love to see a Duet-controlled laser cutter, and support for these is on the development list. We can't yet offer the same degree of firmware support that Smoothieware has, but see and please add your thoughts.

  • The solidoodle should be easy- its a common Cartesian machine, but I was just hoping to find someone that had already figured out a config. It came with some variation of the printrboard, but exactly what variation and the exact firmware was always a bit confused.

    From everything I have read I like the Duet over the smoothie, but cohesion3d offers a smoothie based board with the exact footprint and cable connectors as the K40. That would sure make it the simpler installation, but its only pre-order now, and I am not fond of pre-orders. I have been in the computer industry since 1966, I am familiar with 'real soon now' products.

    I think I will be ordering a duet in a week or two, when I get a couple other projects out of the way.


  • Sorry I searched after posting a new thread.

    I too am very interested in using the duet to power a k40 like laser.

    As this seems like somewhat new ground does anyone know what software they would use for cutting and rasterizing. Right now the k40 stlye cutters seem to use some sort of boot legged Corel draw.

  • Straight from China, K40s usually use old bootleg CorelDraw with a special plug in (sometimes requiring a hardware dongle), or "Moshidraw" – which is pretty much universally despised. Either option is crap, unstable, difficult to use, closed source, proprietary protocols, etc. Plus the controller hardware is usually dubious.

    Getting rid of the provided electronics and putting in a RAMPS / Smoothieboard / GRBL / Marlin / or anything-but-the-crap-it-came-with is one of the higher priority upgrades in terms of usability. It would be nice to have Duet on that list of choices. My K40 is ripped apart undergoing this process (planning on using my spare Smoothieboard for it)

    Once the controller is changed out, Laserweb is one of the better choices for cutting and raster control. Open source, cross platform, g-code based, under active development, good wiki, etc. It plays nicely with Smoothieware in particular because of some of the additional laser power control features in it, like integrating the power level with the acceleration curves (something not possble with RAMPS / Grbl). Adding that into Duet would bring it on par with Smoothieware for laser cutting. I'd start there to see what needs to be added for full laser cutter / rastering support.

    Some older K40s use an analog pot / voltage for laser power control, with no direct way for the controller to vary the power. More recent ones have a different power supply design which runs PWM (I think 20Khz ?) to control power. There's also a separate laser fire contact closure to ground trigger. Some people set their controller to PWM the trigger to adjust laser power, other configurations maintain separate trigger and power control signals. (there's also a laser enable input, which is usually wired to a toggle switch on the control panel.).

    The laser has a minimum value for the laser to fire, usually around 20-25% power level, which is another thing that needs to be considered when implementing the PWM control.

    I'm not fond of the cabling that came with my K40, so having a drop in replacement that uses the same cables isn't a bonus for me. I am not sure all the variations and evolution of the K40 all use the same cabling – they are at least three different controller boards, with several revisions of each, out in the wild. But at the very least, the flat ribbon cable used to drive one of steppers and end stops is inadequate, fragile and does not stay connected well during high speed moves.

    With a new controller you're probably also going to want to add some cabling for some of the common upgrades: another axis for a z-lift bed or rotational axis, cooling water temperature and flow monitoring, toggles for case lighting, targeting laser(s), air assist, exhaust ventilation, water pump, etc. It would be nice to be able to have those integrated with Duet through the unused GPIO / mosfets (probably most of it can be done with existing config options).

    K40s don't come with any sort of safety interlocks, which is insanely risky, so that's also something to consider adding (although they can be added inline with the laser enable switch for a purely hardware solution).

    One final thought: make sure to really triple check the grounding before firing up a K40. The laser's ground return path is through the ammeter in the control panel (!) and then to ground (which is also tied to chassis ground). If that ground path ever disconnects, there's the potential for 20+KV to be floating around in the control panel / metal frame. Yikes. I was uncomfortable with that so I added a separate isolated current meter and safety spark-gap -- which I'd like to hook into the controller eventually via an analog input so I could close the feedback loop on the laser power control.

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