I’m having issues with my Prusa MK2 (kit), and perhaps someone has a few pointers.
It started out with issues with skipped steps and a very wobbly y axis, which I solved by printing holders for the LM8UU instead of zip ties as well as the y motor spacer to avoid bending the motor mount.
But I still don’t get the quality out of it as I expected. The pug is printed from the accompanied SD card to rule out slicing setup errors. The part right above the tail up to the chin is perfect for some odd reason, but the rest of the print have banding problems.
The white Aria is printed with faberdashery white PLA (which I found afterwards is underextruding about 6%). The gray Aria is with the Prusa PLA that came with the printer. Both printed with same gcode.
Running latest firmware.
XYZ calibration shows “all right” (just did a new calibration with latest firmware, previously it came out “severly skewed”). How important is that really? I can’t measure the alignment to be off…
Z leadscrews are straight and true.
Printed a better spool holder without any dragging.
Extruder springs are tensioned properly. (13mm).
I’m kind of stumped on this. I’ve built several RepRaps over the years, but I can’t seem to get the feel for this machine.
Any input appreciated!
I had similar issues in a makergear m2. It took a lot of troubleshooting. It turned out that the belt clamps were loose, and the bed warped a lot from the bit-bang heating.
I ended up replacing the belts with genuine gates gt3 belts, redesigned the belt clamps, replaced the motors with 0.9 degree 400 step motors, and modified the configuration so it uses PID on the bed.
Thank you for the reply @Stephanie_A . Yeah, I don’t like the belt tension system on the MK2, a screw to fine tune the belt feels so much more precise to me.
What bugs me is the MK2 hardware is clearly up to the task…
Previously I found the y belt riding on both the pulley and the idler, which made the Y axis bind somewhat.
I just recalibrated XYZ with the new firmware, and now the pug came out with the good layers in different places. Weird. Printing another one now just to check if the problem is symmetrical. Will post pictures later.
Could it be the current settings on the stepper drivers are off?
What I gather from various forums and videos is it could also be the extruder calibration. I’ll double check that when the print completes.
It could be temperature related, like the previous layer hasn’t had time to cool down. But definitely calibrate the extruder, you can’t sort out other problems until the extruder is calibrated correctly.
Try a few different calibration prints. Make sure circles are coming out round, and try some cubes or a ringing test. There are some backlash test prints too.
The stepper motors should run a little warm, after a long print they should be warm to the point that it isn’t burning hot, but uncomfortable after a while to touch. If they feel barely warmer than room temp, or burning hot then the current is off.
I don’t know if prusa puts heatsinks on the stepper driver ic’s, but if not then definitely get some. The drivers will fail before the motors.
These are printed yesterday back to back with the exact same gcode. So the mechanical error is not consistent, since the layers have problems in different places. Notice the head.
Edit: calculated my extrusion to be off, trying another one now with a multiplier of 1.06.
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So, did another one with M221 S106 spliced into the gcode file. Noticed no real difference, though there were a bit more “perfect” layers.
Then I printed antoher one at 50% speed. And it came out as perfect as I’d hope the MK2 to print.
Seems like the next logical step is some dampening feet or something.
I had a similar problem and was down to my heatbreak … it had a tiny crack in it and think debris entered or was generated there and clogged the nozzle, new heatbreak and the problem is gone … have you noticed a change in noise as the printer is running? And are you in silent mode or full power?
Cant be printing at 50 buddy! Take all year for some things! … ive only ever had to take mine to that for some tricky 1st layers and multiple spikes ect
Thanks @Andrew_Harley
Yeah, the printer is very noisy after I fixed the y axis. I run in high power mode. How much do I have to disassemble to check the heatbreak?
My idea is to run some tests with external perimeters way slower. Or lower the acceleration.
I’m not very concerned about speed on this printer, though it is a bit disappointing, i must say. I have a Mendel90 sturdy which blasts away for when I need faster printing. The MK2 is going to print objects I sell, and I don’t mind running it overnight as stability and surface quality is the main concern.
Well there is things you can do without disassembly. … if like me you are getting heat creeping up into the heatsink then it will be warm to touch … also i noticed a pool of pla on top of my heaterblock … if id used a usb boroscope id of noticed. The end result of it all is the pla was getting soft too far up after the heatbreak and under the force of the extruder motor had nowhere to go other than to swell past 1.75 mm and block it … the whole thing got worse over a 2 week period until i got the big blockage however i first noticed the extruder motor making little skips every few seconds
