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Nozzle Scraping Bed Surface

ยท 6 min read

Nozzle Scraping Bed Surfaceโ€‹

What Is It?โ€‹

Inaccurate bed leveling, low initial layer height, or incorrect Z-offset settings can cause your printer's nozzle to scrape against the printing bed. It might damage the nozzle and the print bed and restrict the filament from flowing out of the nozzle.

If left unchecked for a while, it can build up pressure in the hot end and cause the extruder motor to skip steps. Nozzle scraping is relatively minor but one of the most common issues faced by beginners and new 3D printer users.

What to Check?โ€‹

  • Print bed level
  • Warping issues with the print bed
  • Z-height offset
  • Z-End stop position
  • Initial Layer height setting

How to Fix It?โ€‹

Adjust the Z axis end stopโ€‹

Each axis on the printer will have an end stop to inform the printer about its homing position. If your nozzle is scraping on the print bed, your Z-axis end stop might be located lower than necessary.

Several 3D printers have physically adjustable end stops which you can quickly unscrew and reposition according to the printer's height. It would be best to position the Z-axis end stop slightly above the print bed level. After adjustment, you can easily verify it by homing the Z-axis. There should be a minute clearance between the print bed and the nozzle.

It's recommended to recheck the position of the Z-axis whenever you change your print bed surface. It will help prevent the nozzle from accidentally scratching and ruining your new print bed.

Level the Print Bedโ€‹

An incorrectly leveled print bed will result in an uneven clearance between the nozzle and the printing surface. The nozzle might be too close to the print surface at specific points and scrape the print bed.

It's crucial to level the print bed evenly on all four corners and ensure an adequate gap between the nozzle and the print surface. You can use the business card technique for manual bed leveling to level the print bed properly.

You can refer to this bed leveling guide by Tom's Hardware for more detailed information on bed leveling. Michael from Teaching Tech also has a good test print to check your print bed level.

Adjust the Z-offsetโ€‹

This solution is an excellent alternative to physically adjusting the Z-axis end stop. The Z-offset settings 'offsets' the printer's zero position to a predetermined value set by the user.

It helps you achieve a near-perfect first layer and comes in handy to quickly adjust the zero position while you're installing a new print bed. You can input the Z-offset value directly into the model's Gcode or use a slicer to configure the offset value for every print. Alternatively, you can adjust the Z-offset directly from your printer's display if it supports one.

Wevolver has a practical Z-offset guide that you can use to adjust the Z-offset for your 3D printer. It might differ slightly based on your bed leveling method (automatic or manual), but the basic premise remains similar.

Increase the First Layer Heightโ€‹

You can increase the initial layer height by a small value to compensate for the low clearance between the nozzle and the print bed. It's common practice to keep a high layer height for the first layer as it allows for solid print bed adhesion.

Try to increase the value in 0.05 mm increments so that the nozzle isn't too far from the print bed and the material sticks well to the bed surface.

Ensure a Flat Print Bed Surfaceโ€‹

If the nozzle scraps the print bed at specific locations, you might likely have a warped print bed platform. An uneven print bed will result in improper bed level and inconsistent clearance between the nozzle and the printing surface.

Using a glass bed is the easiest way to iron out any bumps and ensure a flat printing surface. Alternatively, you can replace the entire printing bed assembly and eliminate any bumps on the surface.

Inferior Surface Quality above Supportsโ€‹

What Is It?โ€‹

Supports are essential to provide a base for the overhangs in your 3D prints. But incorrect support settings can affect your print's quality and appearance. If the top of your support is too close to the print's surface, it might leave marks and blobs. Whereas, if there's too much gap between the support and the print, you will encounter filament drooling and poor overhangs.

In an ideal scenario, the support should easily detach from the print's surface without leaving any marks. Moreover, the supported area of the print shouldn't indicate any filament drooling or signs of a support structure underneath it.

What to Check?โ€‹

  • Support Settings
  • Print Geometry

How To Fix It?โ€‹

Adjust the Top Support Z-distanceโ€‹

The vertical z-distance between the support structures and the print is crucial to ensure a good surface quality above the supports. If it's too little, i.e., The supports are closer to the print's surface, you'll have a hard time separating the supports from the print's surface. On the other hand, if it's too high, your overhangs will drool, resulting in poor print quality.

Ideally, the Z-distance should be similar to the layer height value for your 3D print. But, if you're getting poor surface quality, you will need to adjust this distance based on your particular issue.

Enable Support Interfaceโ€‹

A support interface setting enables you to create a dense layer of supports right beneath the print's surface at the end of a support pillar. This dense foundation helps to support the above surface properly and helps in the easy removal of the supports.

You can customize the thickness of this support interface as per your needs. As a starting point, you can use a 4x layer height value as the support interface and fine-tune it according to the results.

Calibrate Support Densityโ€‹

You can increase or decrease the support density to support the overhangs in your 3D prints properly. A higher support density will ensure the support pillars are placed more closely to each and adequately support the printing surface.

However, denser supports use considerably more material and increase print times. You can instead use a support interface and obtain similar results, albeit with a lower density.

Improve the Print Geometryโ€‹

During the design process, try to design the prints for 3D printing. It would help if you avoided steep overhangs wherever it's possible. Even if you need to add some overhang structures, try to keep it under 50ยฐ so that you won't need to use any support structures.

Designing your models for 3D printing right from the start will help you to achieve high-quality models and save considerable filament material and printing time.