Spaghetti junction!

Tried to print this twice with exactly the same result both times. Big blob in the same place twice.
Was adhered to the bed just fine.
Any ideas on what’s going on.
Stone stock E3v2

The big blob is usually, in my experience, a side-effect of the stringing. The strings are loose. One string impacts the side of the nozzle, sticks and melts onto the nozzle. As it continues to move around, it gathers more strings which stick and melt and you end up with the blob.

So the only real question is: why the stringing?

As far as I’ve observed there are two distinct types of stringing: There is the very fine, wispy stringing caused by a nozzle that’s too hot and/or retraction that is too low. Then there’s what you have here which are properly extruded filament that isn’t sticking to anything.

One important question: is the photo of two different attempts at the same model, or were both these pieces printed in one go?

Usually, I get stringing like this if I forget to add supports to an overhang.

Oops - I’ve just been called for dinner. I’ll go into this more when I’m done. If you read this in the mean-time, please fill in if these are two separate prints and if there are overhangs involved. Back in a bit…

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The photo is of the second attempt. I think I’ve solved the problem by loading the stl into Prusa, repairing it then reslicing it though I also changed how I got the stl fro Fusion 360 so a bunch of variables.
Prusa did say there were problems with the gcode so maybe it was truly that.

I have had prints fail in a similar way and a second print identically the same as the first. In my case it was the slicers fault. The stl was fine the printer was too resliced it printed perfect.

@kitedemon When it worked had you used a different slicer?

For what it’s worth, I’ve seen people reporting improved results just by rotating the print on the same slicer.

Interesting. I wonder why that makes a difference.

Rotating the object forces the slicer to re-calculate the route it’s going to choose. If there’s a bug in the algorithm that results in a failed print for one reason or another, making the slicer choose a different route may avoid the situation that triggered the bug.

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same STL and same slicer I just quit it and re opened, re loaded. I didn’t move it (although that is a good idea) and just sliced again. The first was almost like a layer was missed and the extruder lifted up half a mm and started to printing in air. The second print was fine.

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