Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
I was so excited to get my core one and finally put my mk4s+ to rest. The reason I wanted a core one so badly is that I was tired of warping on large PETG prints lifting off the build plate, and needed a heat controlled chamber.
Sadly, the core one has just been a disappointment so far.
1) VFA's. The VFA's are really bad. After learning that the gantry requires two motors to move in a straight line I'm starting to wonder if the gantry is fundamentally flawed in its design. The mk4s+ just requires one motor and wow do those lines look buttery smooth. I've tried everything to mitigate this, but they're still there.
2) Horrid resonance sounds. I have to either print really fast, or turn my model 45 degrees clockwise(which means I lose build plate area). 45 degrees counter-clockwise is quieter than no rotation but still has some resonance.
3) There's a bug with pausing a print and resuming. When you hit pause, the printer doesn't retract the filament properly so you end up with lots of oozing/stringing out of the nozzle. When you select resume, the z-axis takes forever to resume back into position going really slow (while the filament keeps oozing out of the nozzle). Finally, the printer doesn't resume back to the exact z-level it was paused at. This is obviously a bug. From that point you'll hear clicking noises in the gantry as its under stress and you'll witness your print going to crap as its forcing filament on too low of a z level that was already printed.
4) Every time I print the printer bashes the head into the sides over and over while its trying to auto-home. Re-calibrating over and over.
5) Sometimes while cleaning the nozzle is just tries over and over and over again.
6) There was missing plastic fasteners holding the side and top plexiglas panels on. Seriously?
The last one was a minor issue as prusa included extra fasteners. The main issue is this printer just doesn't match the quality of the mk4s+. I wish I had better news.
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
Seems like poor production and poor quality checks
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
The gantry needs 2 motors because it´s a core-xy-printer.
After learning that the gantry requires two motors to move in a straight line I'm starting to wonder if the gantry is fundamentally flawed in its design.
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
Every time I print the printer bashes the head into the sides over and over while its trying to auto-home. Re-calibrating over and over.
That was fixed in 6.2.1 for other printers, so I assume it will be coming to the CORE One soon.
Sometimes while cleaning the nozzle is just tries over and over and over again.
So far I haven't found this to be a more or less common event than it was on the Mk4S. Make sure the nozzle is clean. First thing I turned off was the stupid door sensor so that I can interact with the nozzle without the printer going nuts.
There was missing plastic fasteners holding the side and top plexiglas panels on
Uh yeah. When my machine arrived I had to replace more than half of the rivets as apparently they didn't like the transportation. This is embarrassingly cheap stuff.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
I was thinking the missing fasteners was so you didn't have to remove as many to remove the protection sheets maybe?
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
At least some of them had that whatever you that sleeve like part still stuck in the holes.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
I wonder whether those plastic rivets had been pushed in properly in the first place. They may look cheap, but they usually work!
My 20-year old espresso machine has two of them which hold the rubber mounts of the vibro-pump in place. I have taken them out and put them back in two or three times when replacing the pump or the tubing, which went smoothly enough. But they have never come loose on their own, despite all the vibrations.
Of course it's always possible that some manufacturer has seen the opportunity of producing these cheaper and with lower quality... But in general I don't blame Prusa for the choice of fastener. At least one can't overtighten them and crack the polycarbonate panels. However, since you can't attach the panels very tightly, I wonder whether Prusa should have provided padding strips between the panels and frame to dampen vibrations.
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
After learning that the gantry requires two motors to move in a straight line I'm starting to wonder if the gantry is fundamentally flawed in its design. The mk4s+ just requires one motor and wow do those lines look buttery smooth.
The MK4S (and all other bed slingers) can only print lines which run at 0° or 90° angles by moving a single motor. All other angles require the synchronized movement of the X and Y motors.
The Core One (and all other CoreXY printers) can only print lines which run at +/- 45° angles by moving a single motor. All other angles require the synchronized movement of the X and Y motors.
The real difference is that the CoreXY principle uses longer belts and more idler wheels, which may make it more susceptible to vibration patterns induced by the toothed belt. It's the price you pay for the reduced moving mass in a CoreXY mechanism. It seems that careful alignment, well-matched belt and pulley teeth, and maybe "phase stepping" control of the motors (whatever that Prusa marketing term means) can reduce the VFAs and vibrations. I certainly hope Prusa will get to the bottom of this and will publish suitable recipes and firmware.
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
The gantry needs 2 motors because it´s a core-xy-printer.
No, there are core-XY's that don't use this gantry design. My first printer was an ultimaker which had separate motors for X and Y. A 45 deg angle would require two motors. A core-XY doesn't necessarily imply this design.
The Core One (and all other CoreXY printers) can only print lines which run at +/- 45° angles by moving a single motor. All other angles require the synchronized movement of the X and Y motors.
Yes that's what I was pointing out, but you're wrong that not all core-XY printers do that. My first ultimaker had separate X and Y rails.
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
The gantry needs 2 motors because it´s a core-xy-printer.
No, there are core-XY's that don't use this gantry design. My first printer was an ultimaker which had separate motors for X and Y. A 45 deg angle would require two motors. A core-XY doesn't necessarily imply this design.
The Core One (and all other CoreXY printers) can only print lines which run at +/- 45° angles by moving a single motor. All other angles require the synchronized movement of the X and Y motors.
Yes that's what I was pointing out, but you're wrong that not all core-XY printers do that. My first ultimaker had separate X and Y rails.
That's not a core xy your describing. A Core XY is a specific layout of motors and belts and works as jurgen describes.
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
That's not a core xy your describing. A Core XY is a specific layout of motors and belts and works as jurgen describes.
Ah! Thanks for pointing that out. This whole time I thought core-XY referred to the gantry (non-bed slinger) aspect. I stand corrected. #TIL.
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
For anyone tuning in, the non-coreXY I was referring to in my old ultimaker is called "cross gantry".
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
Sorry to read you're having trouble. Hopefully this is just some new-model growing pains that will be sorted out in the weeks/months to come. I've got a MK4S -> CoreOne upgrade kit on order, so I certainly hope this all gets sorted.
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
I'm in the process of returning mine for repair, should the shipping team actually get back to me to arrange it. I get bad VFAs on straight sides and the resonance of the steel metal sides is silly. When the bed moves up from the middle to initiate a print there is a point where all the metal sides resonate during the bed movement.
I was expecting it to be a bit quieter than the mk4s due to the enclosure but it's significantly louder during a print.
I've already had prints fail with a nozzle collision causing a part of the print to snap which never happened with my mk4.
Wish I'd kept my Mk4!
RE: Core One giant let down from mk4s+. VFAs, resonance sounds, pause/resume bug
I was thinking exactly the same, so this is also a concern for me too. My printers are in the spare room, which is next to our main bedroom, so I can rarely leave prints running overnight. I was hoping I could get away with it with the Core One!
I certainly won't be too hasty to replace the MK4s+ just yet though......
I was expecting it to be a bit quieter than the mk4s due to the enclosure but it's significantly louder during a print.
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