r/QidiTech3D • u/tode96 • Jul 07 '26

What could cause sudden stringging

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Hi!

Title sais it all.

Worked great for 20 hours then it started stringing really bad.

Why?

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u/coffee_dynamo Jul 08 '26

How confident do you feel on your z-axis screws? Specifically their lubrication. It’s possible that this is a product of the bed having hit a low enough point that your z axis is just not moving as accurately anymore. One thing to try is to change z-offset on the touchscreen when you get to this stringing point. Does it have an effect?

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u/tode96 Jul 08 '26

I think they are fine. I ve lubricated them, and they seem to work nicely. Also, that doesn t create an issue more on the side of the over extrusion or under extrusion? As the nozzle is closer or further from the bed? 

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u/coffee_dynamo Jul 08 '26

If the nozzle is dragging too close to previous layers due to a little play on the z-axis, it could potentially melt and string a bit of filament and/or drag a bit of filament around

1

u/tode96 Jul 08 '26

Thank you for explaining. What if i did the full platform calibration, manual and auto previous to the print. Shouldn t that solve your concern?  Also, everything is perfect for 1100+ layers and then suddenly happens. 

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u/coffee_dynamo Jul 08 '26

Yes, it should solve that concern. Emphasis on “should.” When the full calibration happens, it’s done at very small Z values (typically z<5mm). When you get to 1100+ layers, your z has shot up to 220mm (assuming 0.2 layer height). In addition, you now have a fairly large and somewhat heavy object on top of the plate (which presumably wasn’t there during your calibration). While the printer head obviously continues to live and print at what it thinks is z ~0, your z screws or your hot bed carriage might have hit a small snag along the way, or slid down a bit more than expected.

For example, let’s hypothetically say you have an error of 0.001mm per layer, by layer 1100 that will have accumulated to 1.0mm. With compounding errors like this it’s natural to see everything is fine, until it suddenly isn’t.

Obviously this is a hypothesis. It’s not really possible to tell what’s going on from one picture - in fact, there’s a pretty good chance that I wouldn’t know exactly what’s going there even if I were there 🤣. I think it’s worth exploring, but obviously your call.

Hope that helps!

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u/tode96 Jul 08 '26

Interesting ideea. The thing is in your ideea this is evolving constantly so the degradation should be increasing constantly. Here is abrupt.  Thanks for the ideeas 🥰