Nozzle Scraping Bed Surface
What Is It?
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?
- Print bed level
- Warping issues with the print bed
- Z-height offset
- Z-End stop position
- Initial Layer height setting
How to Fix It?
Adjust the Z axis end stop
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 Bed
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.
Adjust the Z-offset
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 Height
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 Surface
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.