I had put a little too much grease near the top of one of my z axis screws and it piled up at the top where the silicone gasket cover is. I left the grease on for a while and when I wiped it off the cover slipped right out. I tried to put it back in but damaged the silicone cover.
My problem is that the bed was near the top which makes the z axis screw too stiff at the top. If I had lowered the bed to the bottom first, the z axis screw would have wiggled easily and I wouldn’t have damaged the silicone cover when I inserted it.
Bambu said it will work fine without it, but I offered to pay for a replacement because I don’t like the way it looks and they were nice enough to agree to send it for free.
I think you’re smart to replace it. Regardless of what customer support may say, I presume the engineers put it there for a reason or they would have omitted it altogether.
Anyway you should be able to just print a replacement, no? And perhaps post it on Makerworld as a spare part (I always collect those, not sure if that alone gives the author any points).
Yours looks like it’s an o-ring, which probably works about as well as the fancier cap.
Not sure that printing one out of plastic would work as well as silicone though. Silicone doesn’t react with petroleum products, like grease, whereas a regular plastic might dissolve, go soft, or otherwise degrade if grease got on it. You wouldn’t want the whole piece to end up getting sucked into the z-screw and chewed up as it spins around. If that were to happen, you really would be better off with nothing.
While this is not the same thing as the silicone cover, this cap might at least keep dust and other debris out. At least I used them because I think it looks cleaner and I am always worried about the cumulative affect of filament particles in the device.
Mine looks the same. It’s a late 2023 X1C. It looks more like a bushing than a seal or O-ring. At first, I thought it was grease oozing from the underside. I took a Q-tip to try and clean mine and the whole inner bearing and that “something” turns freely. It may be to help reduce noise from metal-to-metal contact with the lift rods.
I’d wager Ken is on to something there. Maybe it’s acting like some kind of self-aligning ball bearing?
In the past, whenever I heard talk about z-axis screws, the admonition was to leave them unconstrained on the end that wasn’t attached to the stepper. Otherwise, they might bind. Maybe this helps accomplish that, but without leaving it totally flapping in the breeze.
From the look of the z rod in the center of the bearing… it looks like it acts as an alignment bushing for the top of the z rod into the bearing. I def wouldnt run it without getting a new bushing/cap. That throws your bed out of alignment, that z rod can possibily damage the inside surface of the bearing, and the fact you could end up with a bunch of gunk in the top and between the rod and bearing. Id contact customer sevice or see if any of the z rod replacement videos on the wiki have anything detailed about them.
The ball screws are floating on the upper section for thermal expansion and to prevent binding. The Z axis would likely also function perfectly fine without those bearings and/or flex inserts up top however it looks cleaner with them and minimizes the chance that a user bends those screw rods by accident when the build platform is lowered.
