Cheapest way to connect 3 Hotends

koreandi

Hi there,

can I use a Duet 3 Mini 5+ to hook up 3 hotend / thermistors?
I need to build a small test-rig. The Setup will have one extruder and can be (manually) switched between 3 hotends. Additional I plan to add a Duet magnetic filament sensor.

Can the temp0 and out0 also be used with a hotend or is it restricted to hotbed?
I would like to have a single-board-controller without any extensions boards, if possible. I prefer an ethernet version.

And another question:
Is there any general recommendation about 12V / 24V system?
As I need to purchase the components anyway, it doesn´t matter for me. I have heard that 24 volts runs more smoothly than 12 volts.

Thanks and have a nice day.

droftarts

@koreandi yes, you can use out0 for a hot end heater, so you can run 3 hotends from one Mini 5+ board.

Edit: for the heaters, it doesn’t matter too much if you choose 12V or 24V, because the resistance of the heater is different, if for example, your target is 40W per heater. Don’t use heaters meant for 12V with a 24V supply. However, stepper motors benefit from running at higher voltages.

Ian

koreandi

@droftarts
Great News.
Thanks a lot for your answer.

I think I will go to 24 V even if my setup won´t have any moving axis, except of the stepper.

Greetings
Andreas

jens55

@droftarts, I have to disagree with your assertion that heater voltage is mostly irrelevant. The reason for my objection is that with 12V the current doubles over 24V. In theory that should be irrelevant but if you have any connectors in the electrical path for the heater, you can (and I did) run into issues with burning out the connectors. With a 60W heater and 12V you are looking at 5A which is well past the carrying capacity for many small connectors. If you go to 24V you are at 2.5A.
Line losses also become relevant with the thin gauge wires used in a lot of installs.
I switched my 12V printers to 24V for that and for the better motor characteristics.

dc42

@koreandi said in Cheapest way to connect 3 Hotends:

Is there any general recommendation about 12V / 24V system?

For a new system, always use 24V. It keeps the heater currents lower and allows the motors to move faster.