Core One Assembly Issues - Corner Bulging and Belt Problems
Hello,
Since assembling the printer (I bought it as a kit), I've been having problems with it constantly. I managed to solve most of the problems (which I'll also mention below).
Currently, I have the following problems remaining:
1. Problems on the calibration cube. I downloaded the model from here: https://www.printables.com/model/18760-xyz-test-cube-20mm In the screenshots:
Gray cube: Sunlu PLA filament (before fixing other errors).
Orange cube: Prusament PLA (after fixing almost all errors)
Unfortunately, both cubes have excess filament in the corners. Interestingly, the orange cube seems to be slightly smaller (by about 0.1mm in X and Y axes). What could be causing this corner bulging? Every other model also has these problems regardless of the orientation in which I print the model... Although the orange cube already looks better than the gray one.
2. Curved bottom belt. I don't know why, but when the nextruder is on the right side, the bottom belt is curved in the middle (the upper part of the belt is closer to the rail). When disassembling the nextruder, I also tried to check if it hadn't tilted at the connection. Everything was fine there. The motors also have correctly positioned pulleys (proper spacing and properly inserted on each motor). Can this be fixed somehow and could it have any impact on printing?
Problems I managed to solve and which may have also affected the cube (I plan to reprint the gray cube soon):
1. The printer was unable to lift the right side of the bed. Only loosening the screws on the trapezoidal nut helped (although I didn't like this solution, so I found another one related to solving the next problem).
2. When the bed was at the bottom, the motor screw at the top was rubbing against the plastic on the left side (as if it was mounted crookedly). I tried many things, including tightening the motor a bit. Unfortunately, at some point one of the screws stripped because they are screwed directly into plastic. I found the "Z MOTOR MOUNT R1.stl" model on the page: https://www.printables.com/model/1167816-core-one-printable-parts/files and modified it so that M3 nuts could be inserted from the bottom. Adding a large margin through excessive extrusion (and I could barely fit the nuts in :D). I printed the part in PETG and then replaced it. My surprise was too great. The motor screw was finally perfectly centered in the hole. Interestingly, I could also tighten the screws on the trapezoidal nut.The bed started working flawlessly.
3. Prusament PLA wouldn't print. This was the strangest error I encountered. I could print with every other filament except the one from Prusa. Loading Prusa filament resulted in insufficient extrusion and gear skipping in the nextruder. So I disassembled the entire nextruder and reassembled it (paying particular attention to the gear assembly). After this operation, Prusa filament finally flowed normally through the nozzle.
I also wrote an email to Prusa over a week ago, but unfortunately I haven't received a response to this day. I don't really have time for online chat...
RE:
Hi,
I'm missing two keywords in your list: "gantry alignment" and "strobe tuner" (use the latest RC firmware for the strobe tuner).
If not done, see forum and official Prusa instructions. They are esssential.
RE: Core One Assembly Issues - Corner Bulging and Belt Problems
Yep, that kind of skew in that direction usually points to a bent gantry. Similar issue to what I experienced early on when I foolishly tried to get my belts to 98 and 92 hz no matter what and resulted the gantry getting severely bent.
- Bob Marley
RE: Core One Assembly Issues - Corner Bulging and Belt Problems
...and resulted the gantry getting severely bent.
That is interesting - I take it the belt did not suffer any internal damage?
I know from one other application with a similar belt type that mistreated belts start to "misbehave", such as running one-sided on pulleys. But let's not scare anybody, I haven't yet read about any belt damage incident on Prusa XY.
RE:
Belts are fine. The only issue I'm having is that the belts slowly lose tension and I have to retention them around once every two weeks. It's odd. If it's stretch, that should have resolved itself months ago. I have the tension pulley mod in place with the heat set inserts but I doubt that's the cause. Maybe cold creep? Anyway, I check the belt tension periodically and it's easy to do with the strobe.
- Bob Marley
RE: Core One Assembly Issues - Corner Bulging and Belt Problems
I would prefer not to use the unfinished RC version (at least I've read in many places that there are various problems with it).
But I have already thoroughly performed everything that was written in the article: https://help.prusa3d.com/article/adjusting-belt-tension-core-one_845048
Although I initially had problems with this too. The homing wouldn't go through. It turned out that I had the belts too tight (despite their earlier adjustment).After many attempts, I managed to achieve 96Hz on the upper belt and 92Hz on the lower belt. There's also no play (I performed gantry alignment). I checked this using the website https://belt.connect.prusa3d.com/ on two devices and both gave the same results.
So I don't think that would be the problem. When 6.4.0 comes out (but not in RC), I will definitely use it, although in this case I doubt anything would change.
RE: Core One Assembly Issues - Corner Bulging and Belt Problems
question to the OP: did you verify that the lower belt in the holder behind the extruder is straight? if the belt there is skewed, the teeth in the belt path would probably stretch it straight but in the back you would see that kind of "twist"...
RE: Core One Assembly Issues - Corner Bulging and Belt Problems
Yesterday, I found time to talk to support online. After 9 hours:
- I solved the problem with the corners on the calibration cube. The problem turned out to be the nozzle. Even though I don't use any abrasive filaments, they initially claimed it was my fault. Ultimately, they agreed to replace it.
- I also tried to solve the belt problems. Unfortunately, after many hours, even support gave up, claiming I'd have to disassemble and reassemble the entire Core XY... And they visually inspected a lot of pulleys and gears. They don't have instructions on how to disassemble it... Interestingly, when they presented this printer on their blog, they wrote that the Core XY could be easily disassembled in 10 minutes. So, I'll have to deal with that when I have time... Probably not until Sunday...
RE: Core One Assembly Issues - Corner Bulging and Belt Problems
For the belt, go to this link:
https://help.prusa3d.com/article/adjusting-belt-tension-core-one-l-core-one_845048
Scroll down to the "Extensive adjustment of gantry and belts", not exactly a fast thing but not overly complex as well...
Yesterday, I found time to talk to support online. After 9 hours:
- I solved the problem with the corners on the calibration cube. The problem turned out to be the nozzle. Even though I don't use any abrasive filaments, they initially claimed it was my fault. Ultimately, they agreed to replace it.
- I also tried to solve the belt problems. Unfortunately, after many hours, even support gave up, claiming I'd have to disassemble and reassemble the entire Core XY... And they visually inspected a lot of pulleys and gears. They don't have instructions on how to disassemble it... Interestingly, when they presented this printer on their blog, they wrote that the Core XY could be easily disassembled in 10 minutes. So, I'll have to deal with that when I have time... Probably not until Sunday...
RE:
Are the prints now OK? If it works reliably, belt warping might be a cosmetical non-issue. E.g. some stepper motors are randomly louder than others (I have noisy X and quiet Y but it just sounds odd, doesn't affect performance). I know from other non-3d printing applications that belts can "misbehave", you have to swap them. But as long as it doesn't climb out of the pulleys it might be purely cosmetic.
If it prints generally correctly, what I'd do is check for VFAs e.g. print a cube aligned with the printbed axes, one at 45 degrees for a start. If you can't get those tuned out even with gantry alignment and belt tension, it might be reasonable to replace the belts. Just to rule out one point of failure that can otherwise not be "diagnosed".