Dual heaters on one extruder- power & config. questions

APlanetRider

Hi all! I apologize if my questions seem elementary-I am still pretty new in the 3D printing world and currently building a large format printer out of a CNC router setup using the Duet 2 Ethernet and expansion board (since each of my gantry motors require at least 7A I added external stepper drivers) to control the system. The extruder that was previously purchased for the machine is the Micron Cobra Turbo Flow (found here: https://micron-eme.com/collections/all-metal-extruders/products/cobra-turbo-flow-extruder) which has two heaters per extruder. Micron's website listed specifications for one extruder:

Electrical:
Step motor rated current/Phase: 0.67 Amp. Rated voltage/Phases: 6.2 VDC
Fans: 30x30x10, 12V or 24V (specify)
Heaters: 12V or 24V (specify), 2 x 60 watt

I am running on a 24V system, in theory I should be able to use the Duet to power the heaters since the "most" power the heaters can draw is 120w, making that 5A per extruder. I read in the "Connecting extruder heaters" guide (https://duet3d.dozuki.com/Wiki/Connecting_extruder_heaters) that the Duet2 design is rated to 5A per extruder heater connection but in another section of the guides it says that the Duet 2 can handle 7.5A (https://duet3d.dozuki.com/Wiki/Hardware_Overview#Section_Power_distribution). Can the Duet handle powering one of these extruders or should I use an external power source & mosfet (like one of these: https://www.amazon.com/gp/product/B07C4T9ZTW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) setup?

If I can use both heater ports for one extruder will I need to reassign the port (I assume)? or rewrite anything in the config file?

Eventually we would like to setup a system that has dual extruders and therefore 4 heaters total, would this even be possible on the Duet?

Any direction or advice will be greatly appreciated!

dc42

Yes you can connect both heaters in parallel to a Duet extruder heater output if the total current is 5A.

Alternatively, if your printer doesn't use a heated bed or the bed is controlled by an SSR, you could connect the extruder heaters to the bed heater output. PanelDue won't give the right indications if you do that, but Duet web Control will.