Difficult to describe problem - pictures inside
This is not my first 3d printer, though it is my first Prusa. I'm encountering very strange problems with prints and I really don't know where to start in troubleshooting. This is a brand new i3 MK3S that I assembled.
Note: I know the z-distance is weak on these prints, and I know that is not the cause of this problem. I'll deal with that later.
(EDIT: I tried to embed the posts but I've given up - apologies)
Test 1: Prusa Logo (Source: Included SD Card)
Note the shortness of the base rectangle (the letters overhang) and, though it is difficult to see in this photo, the letters are not horizontally aligned.
Test 2: Benchy (Source: Included SD Card)
This is just an absolute mess, I don't even understand what the printer is attempting to do. This is when I started to suspect that perhaps the gcode on the card is bad?
Test 3: Ben's Live Z-Axis Test (Source: Prusaprinters forum)
Note the uneven incorrectness in the print. Everything is shifted down, yet only the bottom "side" of the square is a mess.
Test 4: Custom 10mm x 10mm x 1mm Square (Source: Me - designed in Solidworks and sliced using default settings in Prusaslicer)
Fearing that this may just be a bad gcode problem for the other prints, I decided to make something from scratch. As you see, the same strange geometry is happening here as well, along with strange decisions made in the gcode (or by a brain damaged printer) to skip entire sections when printing the first layer. I stopped this print before it completed, you get the idea.
I thought this might be a y-axis problem initially, but this isn't showing the weird shifting that I'd expect with a belt problem.
Any thoughts? This is a difficult problem to describe, so it is difficult to know what to search for if someone else has had the same problem.
Best Answer by bobstro:
You are experiencing layer shift. Read up in the instructions on proper belt tensioning. For kit builds, you also need to properly lubricate the bearings. Unfortunately, the bearings in the kits are only lubricated for shipping, not use, and a lot of people seem to miss this step. Do a bit of searching here on the forums and you'll find some good advice on the proper lubrication procedure. Unfortunately, disassembly is required.
A bit of a long shot, but some firmware versions suffer a shift problem due to a known bug in the filament sensor code. Try disabling your filament sensor as a quick test. I don't think this is the problem but it's worth eliminating.
RE: Difficult to describe problem - pictures inside
You are experiencing layer shift. Read up in the instructions on proper belt tensioning. For kit builds, you also need to properly lubricate the bearings. Unfortunately, the bearings in the kits are only lubricated for shipping, not use, and a lot of people seem to miss this step. Do a bit of searching here on the forums and you'll find some good advice on the proper lubrication procedure. Unfortunately, disassembly is required.
A bit of a long shot, but some firmware versions suffer a shift problem due to a known bug in the filament sensor code. Try disabling your filament sensor as a quick test. I don't think this is the problem but it's worth eliminating.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Difficult to describe problem - pictures inside
@bobstro
Thank you for your reply. By putting a name to my problem, you enabled me to find the error. Not only did I find that one of the two grub screws attached to the y-axis motor was loose, but neither of the two grub screws were tightened against the flat portion of the motor's extrusion. I corrected this and can tell already that this issue appears to be resolved. Thank you!
I note this not to contradict you, but for the posterity of this post and perhaps to alert you to the fact that the installation instructions have changed since you last reviewed them. In both the Introduction (Step 1) and the Y-Axis Assembly (Step 24) instructions, the following paragraph is reiterated in v 3.13 of the assembly manual:
The printer's package contains a lubricant, which is intended for maintenance. No need to use it now the bearings are lubricated. There is a dedicated online manual on how to clean the printer and apply the lubricant. See Printer maintenance tips.
This doesn't mean that I made the right decision when I skipped lubrication of the bearings. It may even be worth noting to new users that it is a good idea to lubricate the bearings anyway.
RE: Difficult to describe problem - pictures inside
Additional note: Don't bother printing the GCode files until your Z is correct.
Post a picture of your calibration square (or circle) when done.
RE: Difficult to describe problem - pictures inside
@robert-rmm200
Thank you - once I corrected the issue with the y-axis I addressed the z-offset immediately. I produced a strong xyz calibration cube and have moved on to printing other things. I'll continue to tweak as I go, but for now I believe my printer is in 100% working order.