Replacing Carbide Motion Board With Duet3 6HC

So I have decided to replace the Carbide Motion Board with a Duet3 6HC board and plan to document the process as best I can. It’s a 32bit board with built in integration for a Raspberry Pi. It has six stepper drivers rated at over 4A each, has a ton of IO, and is highly customizable. There is also a very good Fusion360 Post Processor for it.

I am curious what insights others who have replaced their boards with other controllers have.

Also I was wondering how well Carbide Create works on none GRBL based controllers and if it would be possible for me to make a custom post processor.

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Should be a fun/interesting thread.

At this point it only supports the posts that are included in CC install, and those are all GRBL.
I think there is an intent to support more post-processors down the line, possibly even let people write their own, but for now that’s a no.

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That makes me sad. I love CC’s advanced V-Carve.

I was a bit too quick to classify all PP’s are being GRBL flavored, CC does have a “Basic G-code” post. But since I’m not familiar with what flavor of G-code the ReprapFirmware the Duet implements, I can’t really comment whether “Basic G-code” out of CC would be compatible with the Duet.

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Its comparable to Marlin.

Well there is hope then, as far as I can see Marlin follows a quite standard G-code definition

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Yep and any unsupported GCode can be implemented with a Macro in RepRapFirmware.

I find your choice of controller really odd. The Duet is first and foremost a 3D printer controller and sure it takes G-Code and can handle spindle speed but it lacks a lot of CNC-specific features. For example some things that my EdingCNC controller has that a Duet doesn’t (to my knowledge):

  • M6 tool changes
  • Tool length compensation
  • Tool width compensation
  • Backlash compensation
  • Coolant control
  • Look ahead feed

To be fair, these aren’t something everyone needs and you can get by without them, it just seems odd to use a 3D printer controller for a CNC mill/router.

Is there a reason you went for that instead of something more “normal”? Just price?

If it’s price, it might be worth looking at building a LinuxCNC machine. Find an old junk computer and install LinuxCNC and you’ll have an insanely competent controller for the price, though it wouldn’t include the stepper drivers.

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The main reason is I am very familiar with Duet3D and RepRapFirmware (RRF). I have built several 3D printers using Duet 2 boards which I will fully agree are first and foremost a 3D printer controller. The Duet 3 boards however are expanding far more into the CNC space. A number of desktop CNC kits are now using them for advanced functionality compared to GRBL.

  • The M6 command is arguably less powerful than the T gcode RRF has.
  • Tool Offsets can be setup.
  • Coolant can be controlled through GPIO pins and external relays.
  • I can configure my BLDC Dewalt as a spindle in RRF and control its RPM by sending it servo command.
  • In comparison to other GRBL based solutions, the Duet 3 is a much higher quality board than most.
  • Any non-implemented Gcodes can be created using Macros. So for instance if my CAM software insists on using M6 Gcodes I can simply make a file called m6.g, add the necessary gcode commands to convert the M6 to a T command, and put it in the macro directory.
  • Duet’s Macros support GCode Meta Commands like IF statements, FOR loops, Variables, etc. This allows for some pretty crazy Macros to be created.
  • The Duet’s web interface makes managing the system very easy. This includes changing config parameters on the fly.
  • It supports mesh “bed” leveling which can be used to engrave in uneven surfaces like on PCBs.

Over all I think it should work very well for what I am trying to do with my Shapeoko. Is it the best solution for everyone, probably not.

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Seems you’ve thought it through thoroughly.

What about tool radius compensation (G40-42)?

These seem pretty standard in a CNC controller, it’s more of a surprise to me that anyone thinks it’s a reasonable proposition to sell a CNC machine with GRBL of all things, especially these days, when you can put LinuxCNC on a Raspberry Pi.

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They have G40 listed as being something they may implement in the future. I assume that includes G41 and G42 as it is silly to be able to cancel something you cannot enable in the first place.

Personally, I don’t see what you are gaining…

I gain:

  • Two additional stepper drivers which I can use for a 4th axis
  • GPIO pins that can be used for controlling relays which in turn lets me control things like my router, air assist, coolant, lighting, etc
  • Fan controls for cooling my electronics enclosure as well as venting my general enclosure.
  • Z Mesh compensation for things like PCB engraving
  • Advanced Macros for things like probes
  • A web interface for controlling / configuring all of this
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In addition to everything @CthulhuLabs already said:

  • A more modular controller, so you can, for example, swap out stepper drivers
  • More flexibility for upgrades, like servos and motor encoders if you want them
  • More power to handle features like look ahead feed and tool width compensation
  • Macros
    • Flow control - I can (and have) for example, written macros for basic toolpaths like facing, so I can just open up the MDI and face a piece of stock without doing any CAM
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Anyone know what the pin out is for the inductive endstops?

Blue = Ground
Red = 5v
Black = Signal

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I would say if you can implement something like an inductive sensor/BL touch, and use mesh leveling, that would be critical for the larger sized machines like the XXL. I have been 3D printing since the Reprap days and use a simple RAMPS board with Marlin, so I have been intrigued by the Duet, so please post your progress on the Shapeoko.

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I got X moving and homing. And with 16x microstepping interpolated to 256x microstepping it is super quiet. Not that that matters once the router starts up. LOL.

EDIT:
Got Y and Z moving and homing now too.

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One thing to watch out for is the loss of torque when microstepping. I don’t think the stock controller is any different but you are only at about 10% of the stepper’s rated torque when you are in between full steps when using 16x microstepping.

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Yep. I intend to reduce that to 8x or 16x.