Thank you @bearer and @theruttmeister for your input.

After reading some documentation of the Duet 3 and Duet 2 (mainly Wifi and Maestro), I think we are going with Duet 3 board, even if it might be little overkill for the stepper motors. The main reason for this is that it is said in the BigFDM Github page Readme section that NEMA 24 is going to draw max. 4 A current (a single NEMA 24 is used for the Z axis). The Z axis might be somewhat "heavy" considering the weight of the bed plate, bed heaters and the print itself, so you would think it is going to draw a little bit higher current than in a "normal setup". And there is that fact we already have those stepper motors, so better to try to use them.

The webcam with stream support is also what we need and it seems we could do it with a Raspberry Pi 4 B, we could even use an old Android phone as a webcam). There are a couple of different ways to do the webcam stream, but the easiest solution seem to be motion webcam server for the Raspberry Pi.

Also I noticed that BigFDM page recommends to use SSRs for this size bed heaters. With Duet 3 it seems that we would be able to drive these with the four IO pins using four SSR or just connect a single SSR's input to OUT0 and then connect these four bed heaters to the SSR.
As @theruttmeister said:

A 200C thermal fuse attached to the bed is not a bad idea.

Actually, this is a good idea, that would add some extra protection for the night prints! We will check this.

Funny enough, last weekend I talked with my neighbor who has Duet 2 Wifi in his CoreXY style 3D printer and he did say the Duets are quite easy to use after the configuration.

I hope we have the time to make a how-to documentation this summer, so I could put that somewhere here with the builds other users have made.

Thanks!

BR, Henry

Hello all,

TLDR:
I'm seeking an advice or two for large 3D printer build. Would the Duet 3 or Duet 2 be a good controller for a BigFDM 3D printer with 2x extruders, 1xNEMA 23 (2.8 A) and 2xNEMA 24 (4.2A) stepper motors + 4 bed heaters + Raspberry Pi 4 with display or would some other Duet controller be more suitable for the operation? The goal is to make this large 3D printer to be a "easy-to-use", reliable and upgradeable for our university's protolab where users (university students) might have near zero skills with 3D printers. Currently we have a couple of Prusa i3 MK3S printers in our protolab, so our background is fire-and-forget.

The long version:
I'm part of the team which is building a BigFDM 3D printer (the print area is 800 x 800 x 900 mm) for our university's protolab. Our protolab is open for all of our university students with wide ranging 3D print skill levels. So goal for new 3D printer is easy-to-use and reliable.

Our team are following the build instructions that can be found in the BigFDM's GitHub page, here https://github.com/fab-machines/BigFDM. The build consists of two Geeetech MK8 extruders (we might upgrade these in future), four 300 x 300 mm 220 V 750W bed heaters, one 2.8 A NEMA 23 (23HS22-2804S) and two 4.2 A NEMA 24 (24HS34-3008D) stepper motors. The controlling electronics are made in FabLab-style, Arduino Mega based board, TB6600 style stepper drivers and A4988 stepper drivers for extruders etc..

But I have some concerns that the BigFDM's original DIY control electronics are not as safe (mainly the fire hazard) and reliable for our protolab environment as some commercial controllers would be. Don't get me wrong, I do consider the original BigFDM DIY electronics to be a nice way to do all in a single lab. But my main goal is make sure that the electronics are reliable and easy to use, even after I or my team have left the building (as some of us are students which will some day graduate). Also we are looking for a controller which is tested, documented and safe to use in prints that take days to finish. (Or maybe our concern isn't the controller itself rather than extruders and bed heaters..)

For this reason I'm considering to use Duet 3 (or Duet 2) as controller because it seem to be able to drive these steppers directly, also it has some neat functionalities like a web interface (maybe we could monitor 3D printer remotely?), CAN-bus for upgrades, SBC support, many I/O ports...

So I'm looking for some advices/hints if this is at all possible with Duet controllers, or if there are some limitations I'm not aware and need to consider. I have read some of the forum posts regarding the large 3D printer projects and overall it seems doable. One concern though, we have some Prusa i3 MK3Ss, so I'm wondering how big step from Prusa-Marlin firmware to RepRapFirmware we would be taking?

All the best,
Henry