Ukulele print getting knocked by hot end

[ramai]

I've been trying to print a ukulele body in 1 piece. Both attempts have failed 3/4 of the way through. The hot end started clipping the edges, and then it hits hard enough to knock the whole thing out of alignment, then it's spaghetti from there. Any thoughts? It did the exact same thing twice.

[Jimustanguitar]

Sounds like you're overextruding a bit. If you're extruding the proper amount, no filament will be above the current layer and contact the hotend. Turn down the extrusion multiplier by a few percent and give it another go. You can print a thin wall calibration cube to be sure.

[ramai]

If it was over extrusion would it clip even on smaller prints? This only starts printing when the print gets to about 8" high.

[gestalt73]

Hey Ramai,

I haven't really every seen a single nozzle hotend clip or knock off a print like you're describing. You have z-lift set in your slicer, right? If not, try setting it to 1mm.

If for some reason that's not what you want, then it sounds like you're seeing curling at that point in your print, which means you're going to have to tune your print temps, print speed, and part cooling % to give you the part strength you're looking for with no curling around the edges.

Also with tall prints you'll really want to anchor the base of your model. Set up a 10mm brim between 1-3 layers high to help anchor it down. Tall slender models can flex a bit just from the lateral force of the print head for really tall prints.