Bad Top Layers when printing large surface
Hi all, one more issue I'm seeing that I didn't see with a quick search.
When printing a larger surface I get lots of waves along the top edges of the print. But not every print, maybe 2/3rds of them though, but I don't see them in smaller sized prints. I'm assuming this is a z-height issue but I haven't been able to get rid of it with the bed level correction adjustment setting. Also it happens on all sides to some degree (though top and left seam to be the worst) so that would indicate maybe a lower center but I've done the ruler test and checked with a level and there isn't any.
I've got my first layers printing really nice and this just comes up somewhere near the end of a longer print.
Re: Bad Top Layers when printing large surface
That looks like what happens when the corners of your print start lifting from the bed (or the bed is not level) and the nozzle plows into the layer it just put down as a result.
Have you verified the entire base of the print is staying stuck down for its duration?
Re: Bad Top Layers when printing large surface
I thought that might be it too but the piece is flat and didn't lift at all.
Re: Bad Top Layers when printing large surface
What's the height of the object on the picture? How it was sliced (bottom/top layers and infill, if it was used)? Also, what's the filament and temperature settings?
I printed few large flat objects, there were fine.
Re: Bad Top Layers when printing large surface
1cm tall.
Inland PLA 215 for bottom later, 210 for the rest.
build plate 60
Rest of the settings are default Prusa settings for Cura:
.2 layer height
.8 top/bottom thickness
4 layers/shells
60mm/s speed
20% infill
grid pattern
Re: Bad Top Layers when printing large surface
A question and suggestion.
You indicate you have the first later good and this happens on larger prints. Did you check the first layer at different points of the bed, like the back and front, left and right or just the center of the bed? You can use the STL from the live z thread and make copies and move them around the bed to test and check. I made 9 smaller first-layer squares placed at all the edges and the center to see that my back left was different than the rest of the bed.
Back (or Top) left is where the heatbed wire connects to the bed and it has been suggested this affects the mesh bed level in that area. There is a new 7X7 mesh bed level firmware test version that came out toda,y you could try to see if it helps
Those waves are classic examples of too much filament trying to squeeze into too small an area. either live z too low or speed / Flow
You should test the first layer around the bed if you already have not, it is pretty common to dial in the live z in the center of the bed only to have the extreme edges be off causing the waves (it does not take much difference between the center and the edges).
The other thing you could do is adjust the flow (tune/Flow) while printing and watching and dial back the flow to see if that helps. If it does then you know it is not the live z but the flow/speed that is the cause and take corrective action from there.
Strange women, laying in ponds, distributing swords, is hardly a basis for a system of governance!
Re: Bad Top Layers when printing large surface
I've been using the 9 square calibration that I found in the life adjust my way thread and all the different locations printed just fine.
So I decided to lower my z-height some, about .4, as raising it wasn't fixing the issue and it appears to have worked for a while got several prints like the one below:
But the latest one I printed last night is back to being bad again (no changes in settings, adhesion was good, not edges are lifting off the plate, same filimant) in the top right and bottom left only when before it was all corners:
I am wondering of it's over extruding but it's odd that several prints would be fine just to have one fail out like that.
Re: Bad Top Layers when printing large surface
E steps are good so it's not over extruding
Re: Bad Top Layers when printing large surface
That is your top layer huh. What does the first layer look like? That usually happens on a first layer when the live z is too low...
Not sure about cura used to slice, but have you tried to slice the object with Slic3r PE or Prusa control and tried to see if it happens then?
If the first layer is perfect and does not look like that, but it does it only on the top layers, then I do not know.
Strange women, laying in ponds, distributing swords, is hardly a basis for a system of governance!
Re: Bad Top Layers when printing large surface
Yes, two most common causes are z offset being set too low, or the infill pattern being causing each layer to be uneven (usually only with PETG though). So, z offset would be it most probably.
Large prints like this will make it more noticeable if the bed is a little uneven as well.
Re: Bad Top Layers when printing large surface
Warp can be really small and show this type of problem. Easy fix is to raise bed temp to 70c and try again.
Re: Bad Top Layers when printing large surface
That is your top layer huh. What does the first layer look like? That usually happens on a first layer when the live z is too low...
Not sure about cura used to slice, but have you tried to slice the object with Slic3r PE or Prusa control and tried to see if it happens then?
If the first layer is perfect and does not look like that, but it does it only on the top layers, then I do not know.
First layer looks great so does 95% of it. really just looks like the last 2 layers or so have issues.
Warp can be really small and show this type of problem. Easy fix is to raise bed temp to 70c and try again.
Thanks I'll try that.
Yes, two most common causes are z offset being set too low, or the infill pattern being causing each layer to be uneven (usually only with PETG though). So, z offset would be it most probably.
Large prints like this will make it more noticeable if the bed is a little uneven as well.
I've checked the bed with a level and ruler and don't see any issues but it could be something hard to see with the eye.
I found it got better, not worse, with a lower z-offset which I found to be rather confusing as I was certain it was the nozzle dragging. I'm trying to just lower the left and front side of the bed to see if I can get the worst corner to go away.
Re: Bad Top Layers when printing large surface
I've checked the bed with a level and ruler and don't see any issues but it could be something hard to see with the eye.
Sounds like you could do with printing out a set of first layer calibration squares. That's really the only sure way to tell.
Good luck.
Re: Bad Top Layers when printing large surface
I found it got better, not worse, with a lower z-offset which I found to be rather confusing as I was certain it was the nozzle dragging. I'm trying to just lower the left and front side of the bed to see if I can get the worst corner to go away.
There is a control for setting bed compensation for front, back, left, right.
Re: Bad Top Layers when printing large surface
Watched the printing of the last layers tonight and I think it's my nozzle temp. The brand, Inland, is a range between 205-225 and I'm printing at 215 (works well on one of my other printers) and I don't think the edge layers are cooling fast enough and getting moved by the next lines in the layers (as the waves are perpendicular of the nozzle path). Why this only happens with the top layer I don't know. I think lowering the z-adjust is just forcing it to be more stuck so less likely to move.
Going to print again at 210 and see how it is, then 205.
Re: Bad Top Layers when printing large surface
First Layer Cal (Z-adjust) only affects layer 1 thickness. All other layers are relative steps that track whatever layer 1 did, and the overall part thickness is maintained as the part builds.