Some newbie questions



  • Hello im new here and will receive my Duet Wifi + IR Proble sometime this week. 🙂
    I have a few newbie questions that i hope you can help me with^^

    My printer is an modded Wanhao Duplicator i3 V2.1 (Z Braces, Printbite, Titan Aero, etc.)
    My plan is to exchange only the Melzi Board and install the IR Probe for now, the 24V upgrade, new stepper motors and maybe frame changes comes later.

    The Heatbed is currently connected to an extra Mosfet, because as you might know the Melzi board has not suitable connectors equipped and that thing could actually be an fire hazard.
    Mosfet: https://www.amazon.de/3D-Drucker-beheiztes-Bett-Leistungsmodul-Hochstrom-MOSFET-Upgrade/dp/B06ZYQN6VQ

    I know that the Duet Wifi definitely has the right connectors and PCB design but my question is, if it still is an good idea to use that extra Mosfet on the Duet Wifi or if that is completely unnecessary and an waste of space and efficiency?

    Next question: I know of Meanwell as an reliable PSU manufacturer but I haven't found and passive internal PSU that is capable of ~280W from them.
    The PSUs that I found are all equipped with an (probably loud) stock fan. Also I would like to keep things enclosed so my plan is to maybe use that passive cooled LED-PSU:
    MeanWell HLG-320H-24A: https://www.amazon.de/Netzteil-320W-MeanWell-HLG-320H-24A-Schaltnetzteil/dp/B01LYW4294

    I have read that LED PSUs are not as good (not very stable Voltage) as the internal ones but I hope that this one from Manwell will be good. Whats your opinion on that?
    Should I rather get an less expensive standard one like that: Meanwell RSP-320-24: https://www.amazon.de/Netzteil-320-24-MeanWell-RSP/dp/B00UANJYR2
    (I dont want to use the combo of small PSU and an AC-Heatbed.)

    For now my last question: In the Duet-Wiki there is a warning to not tin the cables as that tin could melt due to the high currents.
    Does this just mean don't dip the ends in tin or does this includes to not use tinned copper wiring?

    Thank you


  • administrators

    @Baal:

    The Heatbed is currently connected to an extra Mosfet, because as you might know the Melzi board has not suitable connectors equipped and that thing could actually be an fire hazard.
    Mosfet: https://www.amazon.de/3D-Drucker-beheiztes-Bett-Leistungsmodul-Hochstrom-MOSFET-Upgrade/dp/B06ZYQN6VQ

    I know that the Duet Wifi definitely has the right connectors and PCB design but my question is, if it still is an good idea to use that extra Mosfet on the Duet Wifi or if that is completely unnecessary and an waste of space and efficiency?

    If the bed heater is already wired to the mosfet module then I suggest you keep it. It will be easier than rewiring it, and getting a good VIN connection to the Duet will be less critical because it won't be carrying the bed heater current

    @Baal:

    Next question: I know of Meanwell as an reliable PSU manufacturer but I haven't found and passive internal PSU that is capable of ~280W from them.
    The PSUs that I found are all equipped with an (probably loud) stock fan. Also I would like to keep things enclosed so my plan is to maybe use that passive cooled LED-PSU:
    MeanWell HLG-320H-24A: https://www.amazon.de/Netzteil-320W-MeanWell-HLG-320H-24A-Schaltnetzteil/dp/B01LYW4294

    I have read that LED PSUs are not as good (not very stable Voltage) as the internal ones but I hope that this one from Manwell will be good. Whats your opinion on that?
    Should I rather get an less expensive standard one like that: Meanwell RSP-320-24: https://www.amazon.de/Netzteil-320-24-MeanWell-RSP/dp/B00UANJYR2
    (I dont want to use the combo of small PSU and an AC-Heatbed.)

    I've used cheap LED/CCTV power supplies. They may be less reliable than MeanWell ones and they probably generate more EMI, but I've not had a problem with them. As you are planning to upgrade to 24V later, getting a more expensive PSU probably isn't justified. Is there a reason why you can't continue to use your existing PSU? If you buy a cheap LED/CCTV PSU, I suggest you choose one with at least 20% more power rating than your printer needs.

    @Baal:

    For now my last question: In the Duet-Wiki there is a warning to not tin the cables as that tin could melt due to the high currents.
    Does this just mean don't dip the ends in tin or does this includes to not use tinned copper wiring?

    It means don't use a soldering iron to coat the stranded wires with solder to hold them together. Using pre-tinned stranded wire is OK, but with any stranded wire, use the ferrules provided.



  • Thank you!

    For the cables I will probably replace all the stock PVC 14AWG cables with little thicker 2,5m² silicone insulated wires anyway. The stock ones are way to stiff. But I will do as you advised and use the Mosfet!

    My current PSU (the cheap one from the Duplicator i3) is 12V and I will of course continue to use that when my Duet Wifi comes. (Sorry, my text was a bit misleading^^)
    The mentioned PSUs are the 24V ones that I have in mind for the later coming upgrade (probably already in a few weeks). But I don't know if I should choose the Aluminium-enclosed passive one over the fan cooled standard internal one.


  • administrators

    Another brand of PSU you might want to consider is WEHO. The one I have has a thermostatically-controlled fan, so it only comes on when it is needed.



  • Have you looked at the NES-350-24 mean well - its what i just ended up replacing the internal power supply in one of my printers with. or are you looking for a completely enclosed unit?



  • @dc42:

    @Baal:

    For now my last question: In the Duet-Wiki there is a warning to not tin the cables as that tin could melt due to the high currents.
    Does this just mean don't dip the ends in tin or does this includes to not use tinned copper wiring?

    It means don't use a soldering iron to coat the stranded wires with solder to hold them together. Using pre-tinned stranded wire is OK, but with any stranded wire, use the ferrules provided.

    Agree with all said above.

    AND

    A soldered wire end, when clamped in a screw terminal, will "creep" over time, no matter how much or how little current. This will cause it to get loose, and cause heat at high currents, making it looser… death spiral. Burned terminal or worse.

    Screw terminal clamp = twisted bare wire or "bootlace" ferrule... never solder.



  • @Talanvor:

    Have you looked at the NES-350-24 mean well - its what i just ended up replacing the internal power supply in one of my printers with. or are you looking for a completely enclosed unit?

    Searched it and couldn't find it anywhere in Germany because its EoL. But I found out that the "LRS" Series is the successor of the "NES" and has also the Fan-Off functionality. But sadly can't find that either…
    Also I found out that the "RSP" series has fan control that is fixed to the Power usage. That one would be available on Amazon.

    What do you guys think about the passive "HLG" IP65 rated ones:
    http://www.meanwell.com/productPdf.aspx?i=337
    That thing is a bit expensive (100€) but completely fan-less. But should I expect coil-whine or similar noises from such an outdoor PSU?



  • So my Duet Wifi and IR Probe came today, also my 2,5mm² Silicone Cables (tinned) that I ordered on Amazon.
    Now a new question came up: how can I use these small ferrules? They seem to be to small for 2.5mm² or 14AWG wire.
    I expected them like this: https://d17kynu4zpq5hy.cloudfront.net/igi/duet3d/L52TqyHbtBsOSTXi.large

    As I'll use the extra Mosfet for the Heatbed and will use cable lugs like these: http://www.gsmimpex.in/images/electrical/Electrical%20Cable%20Lugs%20whole%20saler.jpg
    Can I Ignore the ferrules on the "Power In" (that will get <80W) and insert the cable directly into the terminals? Or shall I get bigger ferrules?

    Edit: I tried to insert the cable into the ferrule and its kinda success. About half to 2/3 of the cable-hairs get inside the metal tube of the ferrule, the others are blocked but encased of the plastic of the ferule - is this good enough?


  • administrators

    If the bed heater is being driven separately using a mosfet then the power input cables to the Duet are less critical. So half to 2/3 of the strands of a 2.5mm^2 cable should be plenty. I'll check the sizes of ferrules we supply for the VIN terminals.


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