Z axis lead screw oscillating

Regan Taylor

When the gantry of the printer gets lowered, the left lead screw oscillates massively and it makes a load of noise. I've attached a video of what is going on and a picture of the coupler as I don't think its stretched. Also the lead screw is not bent, I've removed it, rolled it on a table and it is straight

Samuel Pinches

Hi @Regan Taylor 

The problem is not really anything to worry about, it is just the Z move speed is just a little fast and is resulting in resonance. Are you using the custom firmware or factory firmware? In the custom firmware it is possible to reduce the maximum z speed to reduce this.

Some people like to add a z-axis stabiliser to solve this. I don't like this, as the lead screw should not be constrained, as it is the smooth rail that is responsible for the tracking of the z-axis movement.

P.S tips how to embed a video here.... sorry it is not straight forward.

https://jgmakerforum.com/discussion/212/how-to-embed-a-video#latest

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  <source src="https://jgmakerforum.com/uploads/editor/ej/8odvqzk7lyy1.mp4" type="video/mp4">

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</video>

mannymiller

I know this is an old post, but have seen this comment a few times about not restraining the rods. when i first got into 3d printing, i purchased and geeetech i3 pro b.. a very basic kit. This has threaded rods, not lead screws. these were so out of shape, they were a joke. they were secured., so people started to release them at the top. yes they had the smooth rails to support them, but these rods rattling around produced there own noise in the prints. The idea of them unsupported on this printer is not a design thought, its a cost reducing thought. If your couplers are straight and rods are true then there should be no reason not to support them ( im just waiting on bearings to arrive ). you dont see the leadscrews unsupported on the prusa, or any of the better quality machines. another thought, on lowering the z axis from a tall print or maybe working in the hot end. The out of control motion of the leadscrews can not be good for your couplers. And i have already seen alot of posts regarding out of shape couplers.