I am having a bad time with a really annoying problem:
Finally I am getting a nearly perfect first layer after disabling the part cooling fans and the heatbed (which warped the printbed) and using gluestick on the print surface. The nozzle height seems really good (Z0.785 on my printer) and the surface finish after releasing the print is fantastic.
After the first layer the nozzle starts scrubbing through the already printed areas. It seems to get worse layer per layer. This gives a terrible sound and sometimes even offsets layers! Some prints even work and look really good (besides some "scars") but it's not consistent and the chance of failure is given all the time.
What I tried without success was...
- using the part cooling fans
- use higher temperature (using default 195°C)
- changing the z offset (lines are now separating)
- use identical settings for first and all other layers
- optimizing the extruder steps/mm (@Makertech: absolutely great trick, in my opinion a MUST in the build manual!)
- activating z-hop
Does someone have a solution for that? This would be awesome!
I lubricated the lead screw, the Z axis guides and the screw top. Plus I set flow to 0.9. The first layer came out "okay". I hope it stays like that.
The lines were too thin though on the first layer, but it still prints.
Where can I find optimizing the extruder steps/mm in the guide?
Now I set up the excentric guides, the height of the probe, did the configuration via pronterface and it came out ok. But I printed the same model over and over again. I am curious if other models will print as good.
But the excentric guides on the Z axis are the weak point of this printer, if you ask me.
If I understand correctly, the first layer is put down correctly but then the second digs into it? This might be a flowrate issue, try reducing the material flow to 90%. Your first layer from the photo looks fine.
For certain areas of my bed, I get rubbing of layers for first mm because of bed level fail. Also can cause filament jam.
No more playing at moment, seems my MKS is faulty, hot ends won’t track temp so prints never start. One day I hope to be able to print something with a fail.
I do have another cause in mind: do the magnets effect the nozzle height? Maybe the printbed gets bend because the nozzle lifts it?
I have no clue what to try next. A Z-offset change from 0.65 to 0.55 leads to lines not touching on the first layer and less quality in terms of surface finish. 0.65 seems to be pretty great at that. But all other layers after the first one have issues with the nozzly digging into the previous layers often creating layer shifts and failed prints.
One would think that the "magic number" is between 0.55 and 0.65 but only for the first layer. All other layers would need a much lower offset value.
What I tried was:
- belt tension
- roller tightness on Y and Z axis
- different bed leveling approaches (of my warped printbed)
- different printbed temps
- different nozzle/material temps
- extruder calibration
What else comes to your mind?
@fg The steps/mm filament trick is definitely in the works for the build manual.
Also check that your Z-rollers are not on too tight, and that the anti-backlash nut tension screws are not on too tight either.
If you're sure that the z-axis is moving as it should at each layer then it might be an extrusion multiplier issue (over extrusion). In which case I would suggest resetting your board (red button) and re-uploading a fresh copy of the firmware.
We're going to be releasing updated firmware and cura by next week and that might resolve the issue if you haven't been able to fix it by then.
Quick check is your Z steps cal, done same as the E steps. Possibly the drivers need more current to push up the frame or binding in the rods/backlash?