First print issues: bulges and wavy walls
Hello everybody,
this is my first post here in the forum so I would like to introduce myself very shortly:
Robert, electrical engineer by profession, 3D printer by hobby 🙂
I successfully completed assembly and setup of my new Core One about a week ago and immediately started printing a few simple things which had be in my growing list of things to be printed.
Before I had an Anycubic i3 Mega which served me well for more than seven years. But as my models (mostly technical stuff) grew in complexity and this cheap printer was not really useful for anything but PLA it was time to get something serious. The Core One seemed to be a match for my needs. I opted for the kit because I wanted to understand how the printer is build and how it works. It was pretty tedious but rewarding and I can confirm: I much better understand how these printers work 😉 . The old printer, btw. gets a second life a a worthy place.
Ok, now back to the topic. Some of the prints came out sufficiently well, some others showed strange artefacts. The following picture of a rather simple part shows some of the problems:
- First thing which I noticed are tiny streaks on the bottom side. In this print there is only one but others show quite a few. Looks like there were some obstacles like hair or fibres but I am pretty sure the print sheet was absolutely clean. With the first three prints a considerable amount of dust settled on the print sheet while printing. I looks like this was dust left over from assembly. I did not notice this anymore after about 15h printing time, though, so I think we can rule out this a the cause.
- Second thing are the wave like structures on the walls. Not too bad (the Anycubic was much worse here) but still a little bit surprising. I do have some idea what could be the reason here: the printer sits on a rather sturdy workbench (thick wooden plate, steel frame) but still the whole setup seems to vibrate and wobble somehow, especially at times the nextruder moves very fast (sounding a little bit like a kookaburra then 😀). I plan to add considerable weight and structural stiffness to the table soon with a drawer box, however, so this problem may soon be solved.
- Third, and this one really surprises and bugs me: there is some kind of bulge visible on walls with cutouts underneath. In this case this is a opening for a USB C connector, in other cases it was a round hole for heat insert threads. I printed a rather large object (200x200mm) with many holes in it (it's actually a battery holder for batteries from AAA to D) and there these bulges or dents show up as well. Not all in the same direction but pretty repeatable.
I printed this specific part several times with slightly different setups but if anything did not change it was this bulge 😤 .
For simple parts without high aesthetic expectations this may not be an issue. The parts work as intended, these bulges don't interfere with anything.
But, as this example shows it's a visible imperfection and in this case not really acceptable. This part will be the cover of a device (printed in ASA in the final version) well visible and I would not be pleased with this result.
To keep things simple I used standard print settings (in this case 0.10mm FAST DETAIL) and black ESUN PLA (as I still had a new unopened spool).
I have added the project file (zipped 3mf: P108) if anybody wants to see details. I used the smooth PEI print sheet.
Some final words: the belts are perfectly tightened (92/92Hz, tested with a stroboscope), the gantry perpendicular.
I am pretty sure there are some settings which help mitigate these problems. Before I waste too much time (and filament), however, I would highly appreciate hints and/or links to possible solutions.
Thanks in advance an best regards Robert
RE:
The "waviness" on the wall are VFA's (vertical fine artifacts). Most CoreXY style printers seems to have them, some are worse than others. It's mostly due to resonances within the frame, belt tooth pitch, the motors etc. Prusa has not entirely eliminated them but improved them by changing the belt tension. Other manufacturers have switched to 1.5mm pitched belts and toothed belt pulleys. The best way to completely get rid of them if you care about esthetics is to switch to a matte filament. They show up more on glossy filaments. There are various calibration tests available to determine which speeds give you better control over VFAs.
For the USB-C port, that is a bridged extrusion. The quality is a function of the type of filament being use, the temperature and flow rate it's printed at, print speed, the length of the bridge and the orientation of the print. Usually when I use a new filament, I run calibration tests like a temperature tower to dial in the best temperature as well as other tests to calibrate flow rates and speeds. Besides dialing in an optimal temperature and flow rate you can also attach a support.
One recommendation is to download OrcaSlicer. It has built-in calibration tests you can run that can help with these issues if PrusaSlicer doesn't have a built-in filament profile.
After work (it's morning for me) I'll print your object with a different filament that has been dialed in so you can see the differences.
If you are using the 0.4mm nozzle, try printing with 0.20mm STRUCTURAL instead. If it's the high-flow (CHT) nozzle, make sure you have the 0.4HF nozzle selected in PrusaSlicer.
RE:
I opened you 3mf file. To fix the bridged extrusion (or overhang), change Supports to "Everywhere". The one issue with supports is that the contact surface is not going to be smooth. Try it and see. Otherwise, can experiment with changing the print temperature and print speed.
RE: First print issues: bulges and wavy walls
From your single pic its a bit hard to tell but I think the streaks on the bottom look like leaked filament thats been deposited as thin strings on the build plate and then the first layer has just been printed over them.
Wave patterns was already covered, VFA's, adjust belt tensions to 'try' and minimise them but you probably wont get rid of them completely. Try slowing down the print.
Your description of problem 3 is vague. Hygier is interpreting it as the bridging sag across the opening of the USB c port. If that's your issue then yeah adding some snug support in there with a bit of judicious paint on supports and for support enforcers only will help.
I however interpret your issue of bulge on the walls above the usb c port, well that's just your seam position. There's numerous things you can do to try and minimise seams but you cant get rid of them as they are part of the nature of printing. In your preview turn on the seam visualisation and see if they match your problem.
You could tune your filament settings to reduce them or try the various other seam options such as seam gap distance or scarf seam options in the slicer. Depending on what setting you have for their position the slicer will generally try and hide them in a corner. You don't have any corners on that design so it cant do that.
Personally for me I have mine tuned to minimum via careful filament settings anyway and scarf made them worse but some people have had success with scarf seams.
Settings such as retraction and de-retraction speed can also make a difference.
I'd use the seam painting tool to control where they are put. Like the rear of the part when you are looking at it.
RE: First print issues: bulges and wavy walls
Hello,
wow, I am impressed. Really. Thank You very much to both @hyiger and @neophyl for the detailed answers and tips. I see, there are still a lot of things to learn (and tweak) for me with this printer.
What I have been running into had been swamped in non precision of the old printer. The Core One is a completely different can of worm and although I accept the CoreXY mechanism has its weaknesses this can't explain the VFAs and other imperfections I had noticed.
Concerning the belt tension and gantry orientation: the tension is exactly 96/92Hz, the gantry perfectly perpendicular. I'll keep it that way for the moment.
I played around with the Prusa slicer and found out quite a few things:
- Rim or bulge above the USB C hole. @neophyl was spot on, it is the seam. Enabling seam visualisation clearly shows its position exactly where the bulge is visible:
Changing seams to "random" gives a completely different image. I'll give this a try to see what happens:
- Support everywhere: I changed it to this setting. This very probably will enhance quality of the cutout.
- Speed: well, I have to admit I am a little bit confused about where to start. I will try the 0.2mm structural (standard) settings and see how it works.
- Nozzle type: ha, gotcha. I have to look but I vaguely remember that it might be the high speed nozzle. I had ordered the printer together with the MMU3 (I have not assembled yet) and Prusa writes that they deliver it with the standard nozzle. Could also mean "we'll add the standard nozzle as well". I'll check that.
This could explain the fuzzyness as some settings are wrong then. I had not ticked the "high flow nozzle" setting right now.
Ok. I think there is quite some homework for me. When I get new (and better) results I will post them here.
In the meantime again, thanks a lot for the hints and helpful comments.
Best regards Robert
RE:
Check if the nozzle has "CHT" printed on the tube. If it does, then it's the high flow nozzle. As for the seam, instead of random, try painting the seam instead. This will allow you to place it in an out-of-the-way location, like an inside corner.
See attached, I added organic enforcers to the USB-C slot. They are painted on for no particular reason other than to show it off and sometimes it's easier to remove. I've also painted on the seams and added places to prevent seams again as an example. The "Choose File" is not working for me so I attached as media. If it doesn't download, right click and select "Open in New Tab"
RE: First print issues: bulges and wavy walls
Hello,
thanks for the file. I adapted my design with some of your settings:
- added organic support
- rotated the object 180°
- set seams to "rear", increased the gap to 30% and added "scarfs on contours".
Now the seam is on the other wall (without the USB C connector opening).
I'll check the type of nozzle first and then give it a try with these settings. As usual it's worth reading the help and application documents to understand these phenomenons (what a surprise 😉 )
I won't have time to do these tests before the weekend. I will present the outcome as soon as I have something to show.
Best regards Robert
RE: First print issues: bulges and wavy walls
Hi everybody,
I did some tests on sunday and can confirm some success.
- As Prusa has a new firmware with (surprise, surprise) a test for belt tension using stroboscopic light I first downloaded this firmware. The test is really nice but does not show belt frequency as pronounced as my own Arduino based strobo. Nevertheless I had noticed that the gantry was not perfectly perpendicular so I did applied the full therapy: loosen the belts, straighten the gantry, retighten the belts and tune them.
Oh, BTW: the nozzle is the HF nozzle. If I remember correctly I had the settings in Prusa Slicer set to standard nozzle. My fault... - I then printed a version with seam set to "rear", seam gap distance 30% and scarf enabled. Support was set to organic. Settings were otherwise 0.2mm structural. Result was a disaster but quite revealing:
- scarfs left a prominent scarf (pun intended) on some layers. No idea what this feature is useful for, but here it was definitely the wrong choice.
- the 30% seam gap distance led to a much less visible seam (it even started to leave a gap) so this is something I will experiment with.
- straight walls waviness is much (!) better and consistent through all layers. Very probably a combination of recalibration and setting 0.2mm structural.
- I then removed the scar tick, reset seams to "aligned" and rotated the object 45°. Additionally I played with seam painting (really cool feature. I just miss some kind of "ruler" to force straight paint strokes) . Idea was to see if this might have a positive effect on waviness and seam.
The result was quite pleasing. The walls are now sufficiently smooth (hey we are not talking about a injection mold part) and the seam was where I painted it to be. Including the fuzziness of my painting 😀
So what are my lessions learned?
- RTFM. There is plenty of information about the odds and ends of slicing, seams and strength and weaknesses of certain settings. To my excuse I have to admit that the rather limited precision of my old printer (Anycubic Mega S2) gilded many of the details the Core One now duly prints. So this is a steep learning curve for me so far 😉
- rotating the object 45° may help. YMMV, needs experimenting.
- I eventually redesigned to object using 45° corners. No corners pose an unsolvable problem for the slicer. It may lead to usable result - or not.
For the moment there is just on question/problem left: speed settings. There is a plethora of settings you can adjust. Starting from standard settings: where to start adjusting? I doubt that all settings are adjusted proportionally so are there any proven lower speed settings I could start experimenting with?
Right now I will go on with the settings I have and print the same part in PETG and ASA275 tomorrow. I am curious about the results. Even PETG was over the top for the Anycubic so I definitely expect some progress here.
Thanks again to everybody who helped with valuable advice. Highly appreciated.
Best regards Robert