With the printer and accessories in hand, let’s get started.

While the printer arrived quickly, the MicroSD card and PLA filament took longer to get here.

FLSun QQ-S Pro

Initial impression is that the FLSun QQ-S Pro is well made. While I had the slightest trepidation upon opening the box to find about a dozen separate or pre-assembled pieces, (they have to collapse it for shipping), final assembly went together pretty easily. There is nothing daunting here.

  • It’s an all metal design, and while it seems like pretty thin metal, when I finally got the vertical corner pieces in place, it added a surprising amount of rigidity.
  • They used bushings instead of linear bearings. Since there’s really no load on the vertical axis, perhaps they are not necessary.

    The movements sounded a little dry. Forums warn not to use Silicone or PTFE anywhere near your printer because they migrate and are so hard to remove from places you don’t want lubricated, such as the print bed. Forums suggest occasional wipe down of the rods followed by a light oil. FLSun Customer Support suggested grease for the 8mm axis rods.
  • Make sure not to over tighten the belts. They should be looser than you think. Not floppy, but not a guitar string either. Watch some videos on 3d printer belt tension to get an idea of how loose they should be.
  • The cables to the print head are strapped together in a nice tidy bundle, including the feeding tube. We’ll see how that works and if I have to break out the bundle to clear the first clog.

I’m sure the manufacturer knows more about all this than I do, so I built it the way they suggest first, saving any possible mods until after seeing how everything works the way the manufacturer intended.

With the build complete, let’s move on.

Testing and Calibration

  • Temperature Check: An IR Thermometer confirmed both the Bed and Nozzle temperatures were what the display reported.
  • Bed Leveling: This version uses a new touch sensor that attaches magnetically to the carriage with the touch switch directly below the nozzle. Having run the Auto-Leveling routine several times now, it goes pretty smoothly.
  • Z Offset: After the Auto-Leveling routine finishes, you simply remove the magnetically mounted touch sensor and lower the Z axis until a sheet of A4 paper just slides freely between the bed and nozzle. I used a sheet of 20lb copy paper.
  • Calibration: This printer comes with Repetier Firmware which does not respond to the M503 G-Code, however, I found that the firmware update includes a robin_mini_config.txt file with STEPS_PER_MM settings for the Extruder motors and the Axis motors. Simply edit the values, put the file in the top directory of the MicroSD card, and the printer will read and retain those new values on the next power-on cycle, then it changes the extension of the file name as a way of marking it completed, so it doesn’t have to process the file again on the next power-on.

    Note: Loading a new file causes the printer to loose the leveling mesh, so you have to level the bed again after each attempt. You can use the M92 codes to test some values. BE CAREFUL updating the Z value! Changing the Z STEPS PER MM could slam the head into the bed. (Don’t ask me how I know.) The only way the firmware knows where the bed is, is by 370ish mm x STEPS PER MM from the end stops up top.
  • X / Y / Z Movement Calibration: Youtuber “NoLimits3d” measures the mechanical movement of the carriage. This is the correct way to determine your AXIS_STEPS_PER_MM firmware settings.
    Note: When measuring the filament extrusion, he uses the mark and subtract method, which can leave impurities in the hot end. Better to use the disconnect and direct measure method outlined below.
    Sample G-Code:

        G90                  ; set absolute positioning    
        G1 X-100 Y0 Z0 F1800 ; move -100 on X near the bed 
        G1 X100              ; move 200mm to X=100         

        G1 X0 Y-100 Z0       ; move -100 on Y near the bed 
        G1 Y100              ; move 200mm to Y=100         

        G1 X0 Y0 Z0          ; move to (0, 0, 0)           
        G1 Z200              ; move Z up 200mm             

           * https://reprap.org/wiki/G-code for more on G-Codes.

Oddly, the X and Y axis directions are both on an angle relative to the front of the printer. For X and Y, it measured 198mm when asked to move 200mm, so I set X and Y to 101 (= 100 * 200 / 198) for X and Y, and left Z at 100. Note: The firmware apparently doesn’t allow different X and Y values.

  • Extruder Calibration:
    1. Remove the Feeding tube from the bottom of the Extruder
    2. Load the filament into the Extruder gears
    3. Cut the filament at the bottom of the fitting
    4. Extrude 100mm of filament using the menu.
      Note: I had to preheat the hotend before the Extruder would feed
    5. Cut the filament at the bottom of the fitting and measure
    6. It measured 92mm with the default 367 value. After updating it to 399 ( = 367 * 100 / 92 ) it extruded the full 100mm as requested.

That’s as far as I made it so far. Stay tuned.

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