Having a number of issues with prints failing using eSun PETG-HS and while looking for a possible mechanical cause I noticed that the top of the vertical steel lead screws move sideways slightly in the bearing in the very top part of the housing.
I noticed that a small ‘o’ ring is on the top end of the lead screws and it moves sideways within the bearing. That is … their seems to be a LOT of slack.
The fact that a bearing is even used tells me that this should not be the case.
Can anyone with an X1C tell me if this is normal … and there SHOULD be movement? Is the rubber ‘o’ ring a seal or a sideways dampener?
It is normal to see a movement of the Z-axis leadscrew, as it helps to ensure no binding when the heatbed moves in the Z direction.
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The slight movement is normal. The main reason to use the bearing is to reduce rotational friction. The flexible mount allows for a small amount of misalignment or bend in the z-screw without binding. A fully rigid bearing mount would require a more robust frame built with more precision and perfectly straight lead screws (probably larger diameter), all precisely aligned at much more cost, subject to misalignment or binding with temperature changes, for no discernable benefit.
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The lead screw rod is constrained at the bottom and it’s constrained where it goes through the lead screw nut on the build platform. If it was constrained at the top as well, if it wasn’t perfectly straight, it would bind in the nut and/or cause excessive wear in the nut.
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