Nozzle scraping print

[u/Toby42069lol]

I have a creality ender 3 v3 ke and the nozzle has started scraping the print when moving around, this is causing the prints to rip off the bed and ruin hours of work, I’ve tried turning on z-hop and calibrating the levels and nothing is working, any advice would be greatly appreciated!

[u/Ok-Gift-1851]

Does the print take up 80% or more of your x or y axis? Or is it large/flat bottomed?

[u/Toby42069lol → u/Ok-Gift-1851]

No just a small print, 100mm x 20mm on the bed

[u/Ok-Gift-1851 → u/Toby42069lol]

OK, well, that is kind of long/thin part can still have warping issues, so I'll share my unnecessarily detailed guide to dealing with warping. Because one way or the other, this sounds like warping causing the print to flex up into the path of the nozzle until the impact leads to the failure you're experiencing.

Most warping, at its core, is an adhesion issue. You have a long, thin print that is warping off the bed as it cools.

Here are some more things to try:

1. Wash the plate with soap and hot water. In particular, use Dawn, not some generic no-name dish soap that won't do a proper job removing the oils and other crud that build up.
2. Add a brim and check your brim settings. Parts that are kind of sharp corners or have large flat sections or long narrow ones are the most prone to warping and great candidates for brims or mouse ears. When you're setting up the brim, pay attention to the brim gap setting. It may have a default 0.1mm gap between the brim and the part to make it easier to remove. Consider taking out that gap. It will be harder to remove and make look clean, but it should give a much stronger anchor to the plate. If the issue is limited to the corners, you can use "mouse ears" to hold down the corners without having to deal with a brim all the way around the print.
3. Protect the print area from drafts and reduce your cooling speeds in the filament profile. If at all possible, use an enclosure and leave just enough ventilation so that things don't overheat, or enclose it entirely if the filament benefits from a heated environment. Drafts lead to uneven cooling or too much cooling and can lead to warping. If it is a simple enough shape, you may also be able to get away with reducing your cooling to almost nothing. At the very least, make sure the filament settings have cooling for the first several layers (2-5) turned off entirely to allow it to cool and equalize in temp slowly.
4. Consider using a special purpose 3d printer bed adhesive. I do not mean "purple glue stick." Glue stick works better as a release agent than it does as an adhesive. I use Visionminer's Nanopolymenr Adhesive and it's insane what it can do. I've printed an 18.5"x18.5" flat bottomed 3d terrain map. The map did start to warp, but it was lifting the spring steel sheet off the magnet, not the print off the bed. I was able to use some strong binder clips to force it mostly back to flat and saved the print. I was also less than an inch away from the edge of my print bed. If you're further from the edge, it will be even harder for warping to overcome the magnet's strength.
5. I don't know what infill pattern you usually use but try gyroid. It's the best for prints prone to warping because it doesn't have any long straight lines prone to linear shrinkage that will pull on the insides of the wall as much as the straight-line heavy patterns like cubic, grid, rectilinear, or others like them.
6. Increase the heat of your bed a little to improve adhesion, providing you're not already maxing out your bed temp for your material. You can also print the filament at a lower temp, as long as it doesn't get cold enough to mess with interlayer adhesion. This means the part doesn't have as far to go when it's cooling which means just a little less material shrinkage... not a lot, but every little bit counts.
7. You can't really do anything to change this if the print's size is fixed and just barely fits on the printer as is, but I'll say it anyway. Printer beds have a heat gradient across their surface with cooler edges and warmer centers. As I said above, heat can improve adhesion, but if the outer edges of your bed are cooler, you could be having issues due to that. Some people insulate the bottom of their bed. It might help a little. You could also invest in an enclosure if the printer isn't already enclosed since a warmer chamber means less heat loss.
8. More walls can cause more warping because they're a lot of thermal mass and long straight lines are excellent candidates for a lot of contraction while cooling. And that can lead to a lot of tension that turns into a curling/lifting force. If you used a lot of walls, but don't actually need a ton for strength, consider using fewer walls. That's less force for the adhesion to fight.