Duet 2 and Nema 23 - single axis CNC and motor duty cycle

hypnolobster

I'm building a CNC box joint jig, and I'd been planning on using an arduino but I realized I have an unused Duet 2 wifi and paneldue around. That means I don't have to deal with designing any controls, I can just upload gcode and do everything with the paneldue and one external trigger.

I'm using a single Nema 23 (2.2nm holding, 4a max, .4ohm) and a 4mm lead ballscrew to drive a carriage. I haven't finished the mechanicals but it should drive just fine at 2.5-ish amps, though I wouldn't be surprised if I need more.
With a low duty cycle (<1 seconds of runtime every ~5-8 seconds) and no real need for high acceleration or speed, will the Duet 2 handle this, or is it abusive? I'd prefer to not worry about cooling if I can.

It looks like I can pick up an inexpensive DM542T and run that instead, but I wanted to check before I start overcomplicating things.

edit: I'm not up to date on firmware anymore, do Duet 2 boards have the same CNC feature set as Duet 3? If not, is there any particular advantage for such a simple case? Particularly if paneldue and DWC can be simplified for my use instead of always having to look at printer-specific menus.
I'm assuming a Duet 3 Mini and external driver would be the way to go if Duet 2 isn't worth the effort?

droftarts

@hypnolobster I think the Duet 2 will handle this just fine, with a couple of caveats. It runs effectively the same firmware as Duet 3, so all CNC features are the same, just the hardware is different.

If you're running the onboard driver (even just one) at full current, I'd suggest a cooling fan for the Duet.
I'd suggest using the highest voltage you can (i.e. 24V with Duet 2) with large motors.

You can, of course, use an external driver like the one you mention; see https://docs.duet3d.com/User_manual/Connecting_hardware/Motors_connecting_external
Make sure you get one that accepts 3.3V signalling, which can be driven directly from the expansion connector, so you don't have to mess about with 3.3V to 5V level shifting ICs.

Ian

hypnolobster

@droftarts
Great! It's good to know the Duet 2 will handle it on the firmware side. I'd like to keep everything cooled passively since it'll be in a dusty environment, so external driver seems like the way to go. I know TB6600 and DM542's handle that just fine.

It looks like every "big" stepper driver wants 5v, and most of what I can find about 3.3v is that they sometimes work, but it's not necessarily reliable. The expansion breakout board seems to take care of 5v signaling by connecting DIR +, ENA +, and STEP + all together to +5v, with the negative pins on their respective pins. Assuming I'm understanding that correctly, I don't mind having to buy it to make everything work easily.