What would cause this scuffing when printing?
I have the 7x5 bed leveling enabled, but it seems as though the print head might be too low scuffing the print. Most of the surface is smooth but in several areas around the edge of the print the surface is ragged.
Best Answer by Neophyl:
There are several possibilities. Either in isolation or combined.
Check the bottom layer. If it is different in those areas then the part has pulled away from the bed during printing leading to squashed upper layers. Fix by making sure the plater is absolutely clean and free from grease and making sure your first layer live Z is correctly dialled in. Combine this with either an enclosure or a draft shield to reduce the chances of warping.
Insufficient infill and too few top layers - when there's is not enough infill the top layers can sag into the gaps, this combined with not enough top layers to recover from the sagging can cause top layer problems.
Personally looking at the pics though Id be checking your first layer adhesion. If you want the infill checking then you would need to post a zipped up copy of the prusa slicer project file (3mf) so we can slice it with your settings and check through the previews etc.
While you could have a bit of over extrusion as mentioned by beegmouse its unlikely to be the cause as that would effect the whole print.
RE:
Over extrusion.
Check your filament diameter.
Check your filaments dry. (Does it bubble and ooze out of nozzle when still, if so it has water in it and will over extrude.)
It looks like a thin part. If your first layer is not flat (Over extruded or too low a first layer) is will affect later layers on a solid part.
Check your bed is flat. no random debris under the build plate.
If none of this works points to a problem, check and calibrate your extrusion multiplier. There are tutorials on how to do this elsewhere.
RE: What would cause this scuffing when printing?
Thank you very much for a speedy reply!
The first print of this came unstuck from the bed about 75% of the way in. Does that help with the diagnosis?
I think you might be right, I might have an over extrusion issue. The nozzle oozes a lot when preheating and I get quite a bit of stringification. The hatchbox pla I am using has been kept in a sealed container with silica gel.
Are these the instructions you recommend?
https://help.prusa3d.com/article/extrusion-multiplier-calibration_2257
I have new pla arriving today. I will see if using this has any difference.
RE: What would cause this scuffing when printing?
There are several possibilities. Either in isolation or combined.
Check the bottom layer. If it is different in those areas then the part has pulled away from the bed during printing leading to squashed upper layers. Fix by making sure the plater is absolutely clean and free from grease and making sure your first layer live Z is correctly dialled in. Combine this with either an enclosure or a draft shield to reduce the chances of warping.
Insufficient infill and too few top layers - when there's is not enough infill the top layers can sag into the gaps, this combined with not enough top layers to recover from the sagging can cause top layer problems.
Personally looking at the pics though Id be checking your first layer adhesion. If you want the infill checking then you would need to post a zipped up copy of the prusa slicer project file (3mf) so we can slice it with your settings and check through the previews etc.
While you could have a bit of over extrusion as mentioned by beegmouse its unlikely to be the cause as that would effect the whole print.
RE: What would cause this scuffing when printing?
Many thanks for your feedback, it makes a lot of sense (especially the comment about the scuffing only occurring in some places).
The underside is smooth all around. Measuring with calipers, the scuffed areas are about 2.7mm whereas the smooth areas are 3.0mm thick, so the sides may well have warped, as you suggest.
After the first failure, which came unstuck, I saw that the 20% infill on such narrow features wasn't providing enough support, so the print I shared pictures of was done with 100% infill.
The platter was fully cleaned with IPA before the print and I do not have an enclosure or draft shield to use.
I recalibrated the first layer just before this print too. If I decrease the first layer live z value further, I start getting ridges between the filament. Should I accept some ridging to solve this problem?
I have never used a glue stick, would you think that trying it to see if it makes a difference would be a worth while experiment?
RE: What would cause this scuffing when printing?
100% infill, seems to sometimes cause issues, you could try lots of top and bottom layers to exclude open infill in the middle.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Never use 100% fill without a very good reason, you remove all scope for irregularities to self correct.
@neophyl is almost certain to be right, you have a poor adhesion and warping problem.
Wash the build sheet with dishwashing detergent (Dawn/Fairy) and very HOT water. Make sure you are not printing in a draft.
@beegmouse is also probably right about moist filament but it's not the underlying cause here.
Cheerio,
RE: What would cause this scuffing when printing?
Thanks for all the help. I re-ran the first layer calibration. I was at -1.450. I printed test swatches at -1.550 & 1.500. -1.550 showed clear signs of being set too low. I reprinted at -1.500 and the result was much much better. There was still some of the same kind of artifact in a few places, but only at the edges of a very large print (only just fits).
So thanks to all that helped, but also a couple of parting questions...
Should I be happy with the result I had? Could it be better?
I can see small ridges on the -1.500 test piece, so I'm tempted to dial towards -1.450 to reduce that...
On the other hand I'm tempted to dial towards -1.550 to see if I lose the "scuffing" artifact...
I appreciate that the best way to proceed would be to do a whole print at e.g. -1.475 and -1.525, but this is a 3 1/2 hour print.
Should I be happy with what I have?
Do you think I should dial up or down?
RE: What would cause this scuffing when printing?
Forgot to say that the print was 3.00mm wide at the brim all around this time, so the warping was unnoticeable
RE: What would cause this scuffing when printing?
Only you can judge whether the print is good enough for your use-case. It could probably be improved a little more if you accept the time & material costs of multiple retries with fractional adjustments...
I suspect that keeping the print sheet *really* clean will be the most cost&effort effective quality support.
Cheerio,
RE:
Using this test piece https://www.printables.com/model/105404-calibration-strip-for-simple-live-zfirst-layer-cal
I dialed it in even better and got an even better print.
thank you so much
RE: What would cause this scuffing when printing?
I agree with @neophyl on the draft shield and warping. I don't print without a draft shield anymore, especially in the winter. I think less of it as a draft shield and more of a blanket. It's keeping the heat from radiating away at the edges (and especially corners where the heat loss goes in multiple directions) and is effective even inside an enclosure. It's hard to emphasize enough the need to keep the first few layers' temp as even as possible edge-to-edge; warping here can be catastrophic for the print.
I use the "limited" setting in the draft shield drop-down, and give it 30 layers or so. It adds minimal time and material to each print, being just a single bead that makes a loop around the perimeter each layer.