I bought the Due3d 6HC a few years back, in good faith that the company supports CNC machines as advertised on the Homepage.

After many tries to somehow get to a point where i have a minimally viable Workflow, i can conclude that this product is not meant as a CNC Controller - never was and never will be. (While it still might be an very good 3D Printing board!)

The problems:

• There is an CNC Mode, but apart from a few UI tweaks, it does not do anything more than that.
• The main problem is: IT IS NOT REALTIME AT ALL!
• You dont know where the tool is at any given point in time. The tool position shows some buffer value - it might be there at some point in the future..
• It can neither be stopped or change speed until the buffer is empty. In CNC Work, with often many long linear moves + circular moves, this might as well be at the end of the program.
• It does not understand, or worse misinterprets common commands like ARCS. There are a few topics in the forum about that.
• It fails at simplest commands when they are a bit differently formated. E.g. G1 Z-1.0000
• The Gcode Preview never worked, as it expects Extrusions!

Concluding: I know the RepRap-Firmware is a 3d printing firmware, but i assumed that the duet3d team did substantial changes to it, when writing CNC as use case on their homepage. They did not.

I just can assume that they, coming from electronics and 3d printing, have no idea what that even means.

PS: the reason i write this here - google will pick up on it, and maybe I will be able to warn a few people who read this from making the same mistake as me. If you need a proper 3-axis controller go with a UC400ETH and their software.

@dc42 ran the same code a second time, this time on the start of the last segment:
Line 423: G1 X263.075 Y-0.997 Z-7.000 F300.0
it never started this line, instead went diagonally towards zero i guess.. so happend 3x in a row - i was lucky that it is plywood and it did not break anything important, but there seems to be a real problem with this latest RC..
It never reached the last line, Line 424: G1 X263.075 Y-0.997 Z10.000 F1200.0, (the Z-Lift)

I also have a second job, here: 4Holes.gcode It runs before the main cut, and never has any problems. I guess the lines are too short to have any effect with the segmentation.

Here my config.g in case that helps (there is also the M669 S10 command)
config.g

@dc42 ok i just ran another job.. and this time it did not fail, but also did not finish. main3.gcode
it just does not do the last line - a simple z axis move, and instead just stays there. i have to manually cancel it, and then reboot the controller.

I assume it is because of the S10? or some other thing with the current RC version?
using Duet Web Control 3.5.0-rc.1
thanks

@dc42 i see, both parameters are relevant, my question was more in the direction of performance limits. (I am mostly interested in live feed rate adjustments)

Now with S10 it works, although i had two instances of gcode lines being interpreted wrong. I could not reproduce it, but both times it happend, the tooldhead was under load.

It was not lost steps, but the head moving to a totally wrong position.. Could be of course something different, but could also be data corruption.
Edit: and both times it was on the last segment of the gcode.. maybe there is something after all.. If i find out more i will post it.

@T3P3Tony Thanks, found all i need after a firmware update (3.5.0 RC). The GCode viewer is a bit erratic, but it works.
What are good value ranges for the M669 Snnn Segments per second? I have it at 10 for now, it works, but still a little laggy.

and one additional suggestion - why no option to parse the code? check for soft limits etc. I can only upload it and then run it - any syntax or user errors show only when i am already cutting.. As the preview in my - 1-2 year old version - cant give me any indication of problems..

So even with an update to the latest firmware etc. - i think an option for a sanity check would be in order - which in turn would need a separate method besides run. 'Parse File' maybe?

@dc42 @T3P3Tony
Thanks for the fast feedback! I guess i have to dig deeper into the parameters to make this controller useable for CNC.

To my hostile first post - i just spend 3 hours failing at cutting a rectangle with rounded corners out of a piece of plywood - and gave up for today. I have hundreds of hours machine time and 15 years of experience - from semi-industrial machines to tiny GRBL controllers - and lets just say - the out of the box experience with duet3d is not ideal. The tone of my post reflects that.

As for the GCode - i went with the default-ish Mach3 postprocessor (using RhinoCam / VisualMill), and there the arcs got messed up (the two 'lower' ones - out of 4 total).

I bought the Due3d 6HC a few years back, in good faith that the company supports CNC machines as advertised on the Homepage.

After many tries to somehow get to a point where i have a minimally viable Workflow, i can conclude that this product is not meant as a CNC Controller - never was and never will be. (While it still might be an very good 3D Printing board!)

The problems:

• There is an CNC Mode, but apart from a few UI tweaks, it does not do anything more than that.
• The main problem is: IT IS NOT REALTIME AT ALL!
• You dont know where the tool is at any given point in time. The tool position shows some buffer value - it might be there at some point in the future..
• It can neither be stopped or change speed until the buffer is empty. In CNC Work, with often many long linear moves + circular moves, this might as well be at the end of the program.
• It does not understand, or worse misinterprets common commands like ARCS. There are a few topics in the forum about that.
• It fails at simplest commands when they are a bit differently formated. E.g. G1 Z-1.0000
• The Gcode Preview never worked, as it expects Extrusions!

Concluding: I know the RepRap-Firmware is a 3d printing firmware, but i assumed that the duet3d team did substantial changes to it, when writing CNC as use case on their homepage. They did not.

I just can assume that they, coming from electronics and 3d printing, have no idea what that even means.

PS: the reason i write this here - google will pick up on it, and maybe I will be able to warn a few people who read this from making the same mistake as me. If you need a proper 3-axis controller go with a UC400ETH and their software.