Scratches on X-Axis, Twice!
Hi everyone! Quick background on myself: I have been interested in 3D printing for years, but only just bought my first 3D printer (Prusa i3 MK3 Kit). In general, I enjoy tinkering/optimizing things, and like to think I have a good eye for detail. The kit was a great choice for me, as I was able to enjoy the assembly, and learning about how the printer works for the learning and future maintenance. I have cats and live in a humid environment (possible causes?).
Now to the issue. I got my printer towards the end of June this year, meticulously assembled it following a combination of online and printed instructions (mostly online, comments are a great help!). Everything worked wonderfully, though of course my printing technique was simple. Fast forward two months later, there are deep scars on the top smooth-rod on the x axis. Concerned over the damage, I stopped using the printer and contacted support, as all online research pointed to this being rare/faulty parts. After disassembly, I found that one of the bearings was riding very rough, and the rod was scratched on multiple sides. The amazing Prusa support team quickly dispatched replacement rods and bearings to fix the issue.
Once I got the parts, I installed them and things were great again, for a time. When I installed them, I carefully cleaned the rods and avoided getting body oils on them, as well as verifying that the bearings slid perfectly with no noises of any kind. Two weeks later and the x axis started squeaking metal on metal. Upon examination, there are the beginnings of another scar in a few places. As soon as I heard this, I began furiously researching again, only to come up mostly empty. There seems to be little information on lubrication for 3d printing besides "machine oil", so I settled on trying out a recommended "3-in-1" dry lube and hoping the squeaking would die down. I did not lubricate the bearings before installing them or wipe off any of the factory applied... stuff? The squeaking has continued at the same frequency as before (maybe 5 times per print only briefly).
Lastly, the only modifications I have done to the printer personally are to print R3 (B7) extruder parts out of ABS. These parts encountered some minor shrinkage and I ordered PETG, then printed replacement parts which printed wonderfully. I have checked the tightness of all screws to make sure they are not too tight and bending, causing undue stress, but from what I read this is unlikely a cause. I also regularly clean up any debris from the rods when I see it.
At this point, I am tempted to try out Igus self lubricating polymer bearings since they can't possibly scratch the thing. Plus reports of quieter printing is always nice. Though I have seen some concerns listed for these types of bearings. It is just strange to me that only the top x-axis rod suffers damage (favoring the left half of the printer).
What could be causing this issue? What can I do to fix it?
If more pictures or details of anything in particular would help, please let me know. I provided an image of the first rod and scratch, along with the bearing that caused trouble (though it looks fine other than a dent in the plastic siding) as well as general pictures of the printer, and the new lube I recently acquired.
Thank you for reading my wordy post, and thank you ahead of time for any time you spend helping me!
Imgr link, pictures too big to attach: https://imgur.com/gallery/YV1lMGX
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TL;DR - My top X-Axis smooth rod has gotten scratches twice now. New rods and bearings were used the second time around, provided by the support team.