i3 MK3S, x axis rod scratched by linear bearings
i've been upgrading the x-axis and extruder to the mk3s+ parts.
during disassembly i found that the upper x axis rod has two deep grooves worn into its rear-facing side (otherwise i would have seen them sooner), which corresponded to the orientation of the linear bearings. during printing i recently noticed the x axis being a bit crunchy in the middle, as well as small amounts of dirty grease with wear deposits accumulating at the ends of its travel, and expected a bearing to have gone bad:
meanwhile, the bottom x-rod with the single bearing is as good as new after ~300h of use, so it cant be the grease i packed them (most of which disappeared) with or undersized bearings. y-rods are perfectly fine too.
closer inspection and comparing to the new housing parts of the extruder has me suspect the old mk3s parts didnt align the linear bearings good enough, applying additional pressure on the rod and wearing the parts out.
replacement parts are ordered, hopefully they last longer in the new housing parts.
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It is easy to over tighten the screws at the back of the extruder. This can deform the bearings and cause this damage.
If you rotate the rod by 45 degrees they are still useable. Just make sure not to line up the balls in the bearings with the grooves.
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It is easy to over tighten the screws at the back of the extruder. This can deform the bearings and cause this damage.
If you rotate the rod by 45 degrees they are still useable. Just make sure not to line up the balls in the bearings with the grooves.
thought about that too...but the grooves are quite bad and will damage the seals on new bearings quite quickly.
i'll be extra careful with those rear screws this time