HELP! Two duet wifi + two duex5 for two print heads?



  • Hi!

    I am working on a large scale 3d printer. My first idea was to use a single print head with 7 heater cartridges, two extruders and an e3d cyclops. That's why I bought a duet wifi with a duex5 add-on.

    But today I saw this video (see minute 0:10): https://www.youtube.com/watch?v=3UBKscy61jc

    And I'm wondering if it is possible to divide the working volume and add another print head like the one I have described before. What do you think? Is it possible to add another one? How would you do it using duet components?

    Thank you,
    Santiago Serrano from Argentina!




  • administrators

    The firmware now supports Y axis remapping too. So you could have multiple Y gantries, each with multiple X carriages.

    The maximum number of stepper drivers on a Duet WiFi is now 12. The last 2 have to be external drivers connected to the CONN_LCD connector.

    As an example, you could have 2 Y gantries, each carrying 2 X carriages. You would need 2 X drivers, 2 Y drivers, 4 extruder drivers and at least one Z driver. Total 9 stepper drivers.



  • Ok, thank you! But is it possible to use 14 heater cartridges in a duet wifi + duex5? How can I connect them?



  • @_santiserrano:

    Ok, thank you! But is it possible to use 14 heater cartridges in a duet wifi + duex5? How can I connect them?

    The heaters are 24v and 40w from e3d


  • administrators

    Why 14 heater cartridges? Surely you would need drivers for 14 extruder motors too, which is more than the Duet supports?



  • I will be using 2 print heads. Each print head will have 2 extruders (e3d titan) and 7 heater cartridges. So I will need only 4 extruders motors, there is no problem with that. My only problem now is how to control the heater cartridges. I need to know if there is a way to connect them to de duet wifi + duex5 or if it is another way to control their temperatures. Thank you!



  • 7 heater cartridges per print head!!!! That's just plain crazy if you don't mind my saying so. Form my experiments with a 3 colour Diamond feeding 3 filaments in at the same ratio, I was able to print at up 300mm/sec with a single standard 40 Watt heater. The limiting factor was the size of the melt chamber, not the power of the heater. The diamond 5 colour comes with an 80 Watt cartridge and that is just too overpowered. The only way to get that to work was to use 50% PWM to effectively halve the power, otherwise the temperature overshoot was just uncontrollable - to say nothing of the fact that it could potentially have reached over 650 degrees C so was fire hazzard. I have now replaced it with a standard 40Watt cartridge which I have found to be more than adequate and easier to control.

    The limiting factor on how fast you can melt the filament will be this size of the melt chamber i.e the surface area of filament that is in contact with the hot surface, and the time that the filament spends in the chamber. More or bigger heaters wont help. What you are proposing is likely to just burst into flames the first time you turn on the heaters.


  • administrators

    @_santiserrano:

    I will be using 2 print heads. Each print head will have 2 extruders (e3d titan) and 7 heater cartridges. So I will need only 4 extruders motors, there is no problem with that. My only problem now is how to control the heater cartridges. I need to know if there is a way to connect them to de duet wifi + duex5 or if it is another way to control their temperatures. Thank you!

    How many seperate temperatures do you need to control? Are each of these heater cartridges heating a seperate hotend? If not then as Ian says you probably don't need that many. If they are heating different hotends (and you thus have 14 hotends with some sort of switching mechanism) then we have run out of ADC channels on the MCU that are configured as temp inputs.



  • Here is a drawing of what I'm thinking.

    http://i63.tinypic.com/2r5bwaw.jpg

    I will use two systems like the picture. That's why I need 14 heater cartridges. It is important to me to say that the machine is intended to print with a 4mm nozzle diameter and the material that will be used is ABS, that's why I need a long and hot way for the filament to melt and let me print at high speeds. What do you think? Any help?



  • @_santiserrano:

    Here is a drawing of what I'm thinking.

    http://i63.tinypic.com/2r5bwaw.jpg

    I will use two systems like the picture. That's why I need 14 heater cartridges. It is important to me to say that the machine is intended to print with a 4mm nozzle diameter and the material that will be used is ABS, that's why I need a long and hot way for the filament to melt and let me print at high speeds. What do you think? Any help?

    Suggest you contact E3D and ask their opinion on what you propose.


  • administrators

    As Ian says e3d will have a better idea about this.

    You may find that having only two preheat zones rather than three per input is acceptable. Also why complicate it with the cyclops? is that to get a higher flow rate? better to use a larger single extruder. with a 4mm nozzle you are printing thicker than the input filament (3mm or 1.75mm) so designs to look at could be pellet extruders / filament extruders like filastruder:

    https://www.filastruder.com/products/filastruder-kit



  • I could see all 7 heaters being controlled off of one mofset or DC/DC SSR.



  • @number40fan:

    I could see all 7 heaters being controlled off of one mofset or DC/DC SSR.

    Yes I though that but which thermistor do you monitor? Or to put it another way, where in all that do you measure the temperature? What happens if the filament gets melted in the first heater block? - the other heater blocks then becomes redundant. What happens if it doesn't all melt in the first but just goes soft? - can you then push it through the other two? What happens when the filament flow rate changes? - if it slows down there will be too much latent heat in the system and it will drastically overheat the filament. How do you manage the potential heat creep causing blockages? What about pressure build up? What happens…........Oh never mind............



  • 😄 I never said it would work. Just giving him the option to power it up and see the results.



  • @number40fan:

    😄 I never said it would work. Just giving him the option to power it up and see the results.

    Yes, no offence meant or intended. As I said, I thought the same thing but then thought "what about…...etc".



  • @T3P3Tony:

    As Ian says e3d will have a better idea about this.

    You may find that having only two preheat zones rather than three per input is acceptable. Also why complicate it with the cyclops? is that to get a higher flow rate? better to use a larger single extruder. with a 4mm nozzle you are printing thicker than the input filament (3mm or 1.75mm) so designs to look at could be pellet extruders / filament extruders like filastruder:

    https://www.filastruder.com/products/filastruder-kit

    The area of two 2.85mm diameter filament is 4mm, that's why i'm using cyclops and two extruders. I'll be using a couple of filastruder kits but I prefer to produce the filament first, because the filastruder extrusion speed is too low and so it would be the printer if I use it directly.



  • I've been thinking and I decided to make two custom heater blocks and I'll be using 4 or 3 heater cartridges in each. In this way I'll be capable of control the 8 or 6 heater cartridges with the duet wifi and duex5 (the heated bed will have a SSR). And I will contact E3D to know their opinion.



  • Some problems with this approach:

    Cyclops only comes in 1.75mm, you can't use 2.85mm filament with it
    Cyclops has a very high flow resistance, owing to the two 90 degree turns in each filament path
    Having a melt zone 3-4 inches long will result in an incredible amount of back pressure. Hobbed gears will slip or the filament will buckle.
    You do not need 240 watts of heat for this. In even a Volcano hotend, only about 15 watts goes towards actually melting the polymer. The rest is lost to conduction to environment.
    If you're trying to use a 4mm nozzle size, you need 5mm or larger filament. Otherwise you won't get good melt uniformity.

    What is the end goal here? There has to be a better way to manufacture whatever it is you're looking to print aside from 4mm nozzle diameters.


 

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