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3D Printer Nozzle Scraping on the Print. How To Fix?

So, your print nozzle keeps gouging into your 3D prints, leaving scrapes, scratches, and unsightly lines on your model. Nozzle scraping is a typical 3D printing issue, and it usually has something to do with either over-extrusion or a misaligned Z-axis. 

If your 3D printer nozzle is scraping on the print, check over the Z-axis components and settings on your 3D printer. Usually, the cause of scraping is a loose extruder or Z-endstop. However, an unlevel bed, over extrusion, and improper Z-hop or Z-offset settings can also cause nozzle scrapes. 

Many factors can affect how your 3D printer interacts with the Z-axis, and one slight misalignment or incorrect setting can create furrows in your 3D print. So, let’s walk through the probable causes of your nozzle scrapes. I’ll teach you how to solve each incorrect setting and misalignment so you never have to deal with nozzle scrapes again. 

Your Z-Endstop Is Not Working, or The Bed Isn’t Level

The Z-end stop is a mechanism that stops your Z-axis motor from going too low. If your nozzle scrapes into your print bed, this is likely your issue. 

How To Fix

First, locate your printer’s Z-endstop and check the screws that secure it. If you find loose screws, tighten them. Then, you may want to try a test print to determine if the loose screws were the origin of your scraping issue. 

If the screws are tight enough or tightening them does not fix your issue, test the Z-endstop to see if it is working. To do so: 

  1. Grab a blunt-tipped object like a capped pen, screwdriver, or skewer. 
  2. Then, send your printer to the home position. 
  3. As your printer is moving, press down on the Z-endstop. 
  4. Your motor is functional if the printer stops moving after hitting the endstop. 

If the motor doesn’t work, you have found your issue. You may need to replace it. 

However, you need to level your print bed if the motor works. If the print bed is not level, it may be triggering the Z-endstop too late, causing nozzle drag. Hopefully, leveling your bed will fix the issue. However, if it doesn’t, keep reading and troubleshooting until you find the cause of your problem. 

Your Z-Offset Settings Are Incorrect

Z-offset is the setting that keeps your nozzle from getting too close to your print and bed. This measurement will determine where the nozzle falls on the Z-axis as your print, so if it is too low for your project, you will experience scraping and scratching. 

How To Fix

Most 3D printers have a calibration setting to realign and find the correct values for your Z-offset. However, since each 3D printer is different, your printer’s onboard calibration menus may have different names than other printers. 

To determine if your printer provides a Z-offset calibration, use the printer’s display to navigate through the menus. Look for an “Options,” “Settings,” or “Control” menu. 

Then, check for an option labeled something like “Set Home Offsets” or “Offset Calibration.” 

Once you find the calibration option, you can calibrate the offset. For instructions on how to do so, you may want to follow this tutorial from Remain Indoors on YouTube: 

Another option is to use your slicer to enable Z-offset settings. You can find these add-ons for popular 3D printing software such as Cura. 

Using a setting like this will allow you to change the Z-offset depending on your project and enable your slicer to override your printer’s default offset settings. 

However, you’ll have to manually adjust the offset every time you create a model, which can be more of a hassle than calibrating it on the printer. Still, if your printer doesn’t have a Z-offset calibration setting, using your slicer to set the offset for you is an excellent option. 

One more way to recalibrate your Z offset is to alter your G-code. I wouldn’t recommend modifying the G-code if you are a beginner, but it is an option. If you are curious about how G-code Z-offset calibration works or want to give it a go, check out this easy beginner’s tutorial from The First Layer: 

Your Extruder Is Too Close to the Print Bed

This issue is most typical with new 3D printers. If you have assembled your 3D printer incorrectly and positioned the extruder too close to the print bed, you may experience nozzle scrapes. 

Likewise, if the screws that hold the extruder in place are too loose, the nozzle will inevitably drag against your print bed and print, scraping and scratching along the way. 

How To Fix

If your extruder is too close to the print bed, there are a couple of fixes to consider. 

Firstly, if you just bought or assembled your 3D printer, you may have a poorly seated extruder. If that’s the case, remove the extruder by unscrewing the mounting brackets and refer to your 3D printing manual or assembly instructions to determine the proper position for the part. Include any spacers, nuts, and brackets that you might have forgotten to install. 

Then, screw your extruder back onto your printer tightly, following the manual instructions. 

However, if your 3D printer is not new, you may need to tighten up the extruder’s mounting brackets and ensure that each part is secure. Tightening more screws is always a good idea since prolonged use can loosen them over time. Just be sure not to pull them too hard to avoid stripping the screws or cracking plastic parts. 

You Are Over-Extruding Your Filament

If your extruder emits more filament than you accounted for in your layer height, each layer will be slightly larger. 

Those minor differences in layer height add up, resulting in nozzle scraping after printing the first few layers. As your printer works up the Z-axis, the nozzle will scrape deeper and deeper into your print, creating unsightly gouges and lumps. If the layers are large enough, you may damage your nozzle or experience a printing error. 

So, keeping your extrusion rate true to your 3D model’s design is an easy step to reduce nozzle scraping. 

How To Fix

To ensure that your extrusion rate stays constant and matches your model’s layer dimensions: 

  • Adjust your print temperature. Check your print temp and see that it fits your filament’s recommended temperature. Generally, over-extrusion results from too much heat, so err towards the lower temperature for printing a specific filament. 
  • Reduce the extrusion multiplier. Check your extrusion multiplier if you notice over-extrusion, and everything else seems fine. Most slicers will use a default multiplier of 1, but you may need to decrease this rate by subtracting 0.025 (2.5%). So, if your current multiplier is 1, your new value would be 0.975. 
  • Adjust the extrusion/line width. Extrusion width (Line Width in Cura) represents how wide each layer will be as your nozzle squeezes out the filament. If the extruded filament is too broad, it may create raised bumps where your nozzle will scrape against your print. Ideally, your extrusion width should be 1.5 to 2 times your layer height.

You Have Disabled Z-Hop (Vertical Lifting)

Z-hop is a feature that raises your nozzle as it moves from the end of one layer to the beginning of the next layer. The hopping motion – also called vertical lifting in many slicers – ensures that the nozzle will not scrape the top surface of your print, protecting it from scrapes. 

In addition, using Z-hop will reduce stringing and artifacts since it will give you a crisp, clean break between each layer. 

How To Fix

Enabling Z-hop is usually a good idea for most 3D prints, and it’s exceedingly simple to do. 

To enable Z-hop or vertical lifting:

  1. Find your extrusion settings on your slicer.
  2. Look for a setting called “Retraction,” “Vertical Lift,” or ‘Z-Hop” (each slicer labels this setting slightly differently).
  3. Set the value to the same size as your nozzle. For example, a good rule of thumb is to use a Z-hop of 0.4mm (0.02 in) for a 0.4mm (0.02 in) nozzle. 

You can raise this value, but you likely won’t notice much difference beyond the recommended hop height. 

You might also notice some other settings related to your Z-hop. For example, in Simplify 3D, you’ll find options that determine when the nozzle hops and how far it will travel before it returns to the printing position. If you see such settings, disable them to allow the nozzle to lift every time it travels to another area on the bed. 

Summary

If your printer nozzle is scraping on your 3D print, you likely either have an issue with your Z-axis hardware or calibration, or you might have a problem with over extrusion. To fix these issues, you’ll have to investigate your Z-endstop, level your print bed, reseat and secure your extruder, enable Z-hop, or adjust your extrusion for more even layer lines.