Mysterious z banding issue at certain heights
I've been having this repeating issue that's had me pulling my hair out for many months. I print these rod shaped parts which generally print very nicely, however for no obvious reason, they will suddenly start printing with prominent z banding ridges. Oddly, they typically only show up if the rod is the only thing being printed at that z height. You can see from the image that the rod is smooth up until the height of the other part being printed. After that, the rod is very ridgey.
An important note is I'll take this same gcode and run it on another printer, and it prints perfectly. Once a printer gets this issue, it will persist on that printer for any other prints. I've tried replacing nozzles, cold pulls, replacing hot end ptfe tubes, checking belt tensions, lubing rods, tightening frame screws, restarting the printer, cleaning the extruder, replacing extruder gears, changing out filament rolls...and nothing seems to fix the issue. I have quite a few mini's and this is a very common issue for me. I've had it pop up on half a dozen of my printers. The fixes above usually do nothing, but have occasionally helped the issue for some time.
Any advice on anything else I can try to fix, maintain, or replace? I simply don't know what else to try at this point.
Thank you in advance!
RE: Mysterious z banding issue at certain heights
I'm having trouble adding a photo to the thread. Getting an error saying the action has been blocked. Any advice on getting the photo to show up? I'm new to this forum. hoping to get involved when/where I can with the prusa community. I've been using the Mini for a few years now, and think I could help some users, and can clearly use some guidance myself. Thanks!
RE: Mysterious z banding issue at certain heights
If you cannot use the default Insert Image button, you can always upload it to another host (like Imgur) and share the link here
RE: Mysterious z banding issue at certain heights
RE: Mysterious z banding issue at certain heights
What about bed adhesion? It seems a relatively thin piece, so are you using a large brim to avoid possible movements of the piece itself while the Y-axis moves?
And have you tried the option "Print outside perimeters first" in PrusaSlicer?
RE: Mysterious z banding issue at certain heights
It is a fairly thin part, about 0.5in diameter and 4.5in tall. It does, however, have a widened part on the bottom to improve contact with the print bed and sticks surprisingly well. I do realize that the part looks challenging to print well, but I don't typically have any issue with it on my other mini's that are working well. For example, I'll be printing this part repeatedly for weeks on end, then suddenly these bands will appear on one of the prints and each successive print thereafter on that particular printer. Because of this, I believe it must be hardware related.
That's an interesting thought on printing the external perimeters first. I have not tried that, but will give it a go today. While I don't know if that would be the route cause of the issue, if it makes the print less susceptible to the banding than I'll happily adjust the slicing settings to do that. Thanks!
RE: Mysterious z banding issue at certain heights
So, I'm still a complete noob, but I'm wondering if it's layer time? Have you messed with minimum layer time settings at all?
Also, if it only happens when the rod is the only part being printed, and you print these a lot, what would happen if you change your printing so that you always print a minimum of two of these rods at all times? That would mean you don't have a single rod that's being printed at that height.
RE: Mysterious z banding issue at certain heights
chris i have the exact same problem with my mini and it is very frustrating. i have not yet been able to resolve issue. i typically print everything in .1mm and have found out that the same exact print that goofs up in .1 prints perfect in .2. even more frustrating the .1 occasionally prints perfect. you might try moving this to printing help section might get more input. did external perimeter first help any?
RE: Mysterious z banding issue at certain heights
That seems like you get squashed lines because the arm is dipping down.-
I had read on reddit that people said that you had to get a Z-axis brace to stop getting squished layers. I created this stress tower to check it myself. https://www.printables.com/model/467550-the-stress-test-tower
On the left is before the brace, on the right is after the brace. I had the lines that you show in your pictures from about 65% and upwards of the minis print height.
You can find the brace here: https://www.printables.com/model/51415-prusa-mini-z-axis-brace/comments/834236
Printer: Original Prusa Mini+
Nozzles: E3D 0.25, E3D Nozzle X 0.4 , E3D 0.4, Bondtech 0.6 CHL
Printables: Tysonsw
Mastodon: [email protected]
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RE: Mysterious z banding issue at certain heights
1. Check all screws and re-tighten (including belt tension checking)
2. Check firmware and update if necessary.
3. Check wear surfaces for corrosion (are the roods still shiny & smooth?)
I would be willing to bet one of your Z assembly bolts is a bit loose.