Need help with ordering new to duet…



  • I am building a corexy with a fixed build plate. build area is 1000x1000x1000mm I need a setup able to run 4z steppers, 2x/y steppers, heated bed that is 110v main but controlled by the board using a heat sink and solid state relay, 2 hot ends and 2 bondtech extruders.



  • that answers my question. I was looking at the wrong expansion board and could not figure out why there were no drivers lol. So next question what are everyone's thoughts on running 4 independent z steppers? i just did not think one or two could handle the weight of the xy setup. it is 20x40mm linear rail that is 1100x1100mm. If I could use one to drive all 4 screws that would be great but to get a serious stepper it will draw 4+amps and I think I read the duet will only handle 2.4.


  • administrators

    If the bed plate and frame are sufficiently rigid then 3 stepper motors would be better. Use 4 only if you can't make it rigid enough. I suggest Nema 23 motors rated at 2.8A or 3.0A for the Z axis.



  • @mhallett:

    that answers my question. I was looking at the wrong expansion board and could not figure out why there were no drivers lol. So next question what are everyone's thoughts on running 4 independent z steppers? i just did not think one or two could handle the weight of the xy setup. it is 20x40mm linear rail that is 1100x1100mm. If I could use one to drive all 4 screws that would be great but to get a serious stepper it will draw 4+amps and I think I read the duet will only handle 2.4.

    For info, I use a moving bed instead of a fixed one so although I have a smaller bed (400 x 400 x 10mm thick) it weighs around 7kg in total. I am able to drive this with a single Nema 17, continuous belt and 1:1 gearing with 1mm lead screws. I'd doubt if your XY gantry is going to weigh more than 7kg but do the maths. If you use these (IMO silly) multi start screws that have 4mm lead, then you'd need 4 times the torque but it'd be better to use gearing which will give you desired layer height resolution.


  • administrators

    Z axis on cartesian/CoreXY printers don't tend to need to move quickly so the acceleration required (and hence the torque) is lower than for X, Y.

    If you want auto bed levelling then you need a suitable probe, and 3 z motors is the best choice. If you don't want to auto level your bed then a single Z motor with belts/gearing may well be the best solution.



  • I just ordered 4xnema 23 and 4xnema 17. I also ordered the 4 Acme rods an enough belts and pulleys to mess around with different setups till I find the best one. Is there pre-writen firmware for a corexy and the duex5 or do I have to build that from scratch/



  • @dc42:

    If the bed plate and frame are sufficiently rigid then 3 stepper motors would be better. Use 4 only if you can't make it rigid enough. I suggest Nema 23 motors rated at 2.8A or 3.0A for the Z axis.

    I thought the max amp on the board per stepper was 2.4A?



  • Can you share the design? - I am considering building something that size 🙂



  • I am making a guide video along with all that supplies needed and where to get them. As soon as I am done with the build and get it working I am going to release everything. My build is on the pricey side but there are no crap parts, I only used the best that i could find. I think in total I will have about 3-4K into it but I was sick of these junk kits that you buy. shoot me a Email at m.hallett@ymail.com and as soon as I get it all together I will email it to you.


  • administrators

    @mhallett:

    @dc42:

    If the bed plate and frame are sufficiently rigid then 3 stepper motors would be better. Use 4 only if you can't make it rigid enough. I suggest Nema 23 motors rated at 2.8A or 3.0A for the Z axis.

    I thought the max amp on the board per stepper was 2.4A?

    It is at present; but stepper motors that are run at their full rated current get very hot, so it's normal to run them at no more than 80 to 85% of their rated current.


  • administrators

    @mhallett:

    I just ordered 4xnema 23 and 4xnema 17. I also ordered the 4 Acme rods an enough belts and pulleys to mess around with different setups till I find the best one. Is there pre-writen firmware for a corexy and the duex5 or do I have to build that from scratch/

    You don't have to build firmware for the Duets yourself unless you are doing something very unusual. Instead you use https://configurator.reprapfirmware.org to generate configuration and homing files, and you transfer them to the SD card. See https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_Cartesian_printer and https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_CoreXY_printer for more detail.



  • @dc42:

    @mhallett:

    I just ordered 4xnema 23 and 4xnema 17. I also ordered the 4 Acme rods an enough belts and pulleys to mess around with different setups till I find the best one. Is there pre-writen firmware for a corexy and the duex5 or do I have to build that from scratch/

    You don't have to build firmware for the Duets yourself unless you are doing something very unusual. Instead you use https://configurator.reprapfirmware.org to generate configuration and homing files, and you transfer them to the SD card. See https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_Cartesian_printer and https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_CoreXY_printer for more detail.

    Thanks for all your help, the only ting I am doing differently is moving the xy gantry for the z insted of moving the bed. So I should be all good as long as I reverse the z homing movement.



  • @dc42:

    @mhallett:

    @dc42:

    If the bed plate and frame are sufficiently rigid then 3 stepper motors would be better. Use 4 only if you can't make it rigid enough. I suggest Nema 23 motors rated at 2.8A or 3.0A for the Z axis.

    I thought the max amp on the board per stepper was 2.4A?

    It is at present; but stepper motors that are run at their full rated current get very hot, so it's normal to run them at no more than 80 to 85% of their rated current.

    So if I run 3 steppers would it be two in the back direct drive to the Acme rods and one in the front with 1:1 gearing to the two Acme rods in the front using belts and pulleys?



  • What we are saying is to only use 3 Acme rods that way you can't twist the bed which is what commonly happens if you use one in each corner think of a 4 legged stand as opposed to a camera tripod which is the most stable


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