Upgrading QIDI X-Pro printer [bunch of questions]

  • Hi,

    Will try to write as short as I can )

    Right now I have QIDI X-Pro printer and want to upgrade it with a new motherboard so I need your advices... But first thing first - I have chosen QIDI X-Pro by this advantages(I thought so):

    1 - Full steel frame (veeeery heavy!)
    2 - Fully enclosed chamber with windows, lids (+ for ABS)
    3 - 12mm guide rods for a bed and steel bed holder(don't know how to call it...)
    4 - Heated bed with magnets and PEI covered spring steel sheets
    5 - Dual extruder setup(thought about using support materials for complex prints)
    6 - Price! Just US$800 !

    So I haven't chosen something like Prusa I3 because of lack of enclosure, some Deltas because of the same "problem" and Bowden extruders.
    What do I need? I need a printer for prototyping engineering samples, so they should be accurate enough dimensionally and with good looking surface.

    So there is a problem... I am getting very accurate and good looking prototypes only when printing 10mm/s ! If I go 20-30-40mm/s I will get bad corners (Omega shaped), very bad seams(blobs when extruder goes from internal perimeter to external and making Z shape movement)

    So why do I want to change a motherboard? Right now I have a closed source Chinese MB with almost no configuration, with no linear advance(that could solve blobs at corners and Z-shaped movements)

    So I saw Prusa I3 MK3 new model with silent moves, fast, accurate and etc... I want to upgrade and get the same Pros without Prusa's Cons!(Dual extruder, fully enclosed and etc..)

    Some tech specs for my QIDI X-Pro:
    Motherboard: Chitu 4.2
    Power: 350W 24V MeanWell
    Build volume: 230x150x150(X Y Z)
    Drivers: Unknown, covered with radiator(Could be something like 4988 I think)
    Z: 1.8deg , 13.2V(!), 0.4A, 33Ohm, 45mH, 2.4Kg/cm (using Tr8*8 lead screw)
    X and Y: 1.8deg, 4.96V, 0.8A, 6.2Ohm, 10mH, 2.4Kg/cm (with 5mm shaft)
    E0 and E1: 1.8deg, 4.83V, 0.84A, 5.75Ohm, 9.3mH, 2.8Kg/cm(direct drive extruders)

    Pulleys: 17teeth on Y(counted 5 times... can't understand why 17!), X is unknown
    Mechanical endstops on all 3 axis

    So it is a clone of Flashforge Creator Pro and similar.

    So as you see I have a full mess not only with electronic part, but with mechanical too...
    After I have found all tech specs today first idea was not to upgrade but to sell and buy/build something better...

    So what I want finally get: good quality finish and dimensional accuracy(geometry like corners, "round" circles) and more than 10mm/s speed(maybe 30mm/s minimum?.. but won't be upset with 50mm/s too πŸ™‚ ) And mesh auto-leveling would be nice too ) So I don't need crazy 100-150mm/s printing speeds

    1 - Should I upgrade or just change it? Upgrade will be costly but I will know for sure that everything is "top quality" and built as it should!
    In case of upgrade I definitely should change all steppers too...
    2 - Should I change belts from Noname Chinese to something better? Some carbon reinforced?
    3 - Should I change pulleys to 16 or 20t ?
    4 - Should I change Z screw for Tr84 or even Tr82 for better precision? (As I don't need high speed on Z)

    What else should I look at?

    Thank you very much for advises and insights πŸ™‚ (And sorry for my English, it is not my first language πŸ˜‰ )

  • Moderator

    A full gut and upgrade is possible, but at that point maybe it would be better to just build a better design to start with? By the time you upgrade everything you'd spend about the same. If I were you, I would sell the QIDI and build a RailCore II.


    It would be very precise and fast, fully enclosed, similar or better build volume and would probably cost the same as upgrading the QIDI. (800$ + upgrades and throwing away half of what you paid $800 for) versus about $1400 for the RailCore.

    You can see what other people have done with the Flashforge Creator here: https://forum.duet3d.com/search?term=flashforge&in=titlesposts&matchWords=all&sortBy=relevance&sortDirection=&showAs=posts

  • Thanks for links!
    I am thinking about just building from scratch but I will still loose a lot of money as I won't sell QIDI for $800 πŸ™‚ I think it would be closer to $400-500? So I will need to spend $900 extra on a new build that you advising.

    And upgrade will be like $200-300 (Duet 2 Maestro , no LCD(I really don't need it, maybe later), new good steppers/pulleys/belts). What do you think?

  • administrators

    @briskspirit, the Maestro would be a good match for the low-current motors and 24V power supply that your printer uses. To see what speeds might be achievable with those motors, use the back EMF calculator at https://reprapfirmware.org/. Connect the two Z motors in parallel, not series.

    If you want more speed than those motors can provide using a 24V supply, then you will need to change to higher current,. lower inductance motors - but not too high a current if you are using a Maestro.

  • Thanks! What about Duet 3? You will soon show it at the show? πŸ™‚ Which drivers it will have?

    About Z steppers - I have only one Z stepper: 1.8deg , 13.2V(!), 0.4A, 33Ohm, 45mH, 2.4Kg/cm (using Tr8*8 lead screw)
    It is SOoo weak!

    And right now I don't have any problems with steps skipping and etc. The main problem is in (ihmo) firmware and no linear advance.

  • Moderator

  • So today I have calculated my steppers for XY that I have right now:
    Approximate peak back EMF due to rotation per motor: 7.8 V at 200.0 mm/s
    Approximate peak back EMF due to inductance per motor: 1.9 V at 200.0 mm/s
    Step pulse frequency: 18.8 kHz at 200.0 mm/s
    Speed at which torque starts to drop (low slip angle): 174.2 mm/s @ 23.2 kHz
    Speed at which torque starts to drop (high slip angle): 236.8 mm/s @ 31.5 kHz

    This means that I don’t need to change them? And how to take into account weight of the carriage?

    One more crazy idea was to split carriage for 2 independent extruders. But that will give me more weight on Y axis..