Bumps along Z-axis (SLS)

A blurred laser spot can cause bumps or other surface irregularities on SLS printed parts. On Fuse 1 generation printers, this blurring may be caused by contamination on the optical cassette or on the upper laser window.

SLS printed parts exhibiting bumps along their Z-axis

Visual symptoms

  • Bumps or other distortions that extend vertically along the surface of a printed part

Common causes

  • Contamination on the optical cassette
  • Contamination on the upper laser window

Troubleshooting steps

Follow the troubleshooting steps below to check for possible causes, beginning with the most likely cause of the print defect.

Note:

Make sure that your firmware and PreForm versions are up to date. To update your PreForm version, refer to the FAQ article How do I update PreForm?.

Step 1: Clean the optical cassette

Any contamination, dust, or debris on the printer’s optical surfaces can weaken or diffuse the laser light, resulting in a print failure. Contamination is most likely to occur on exposed optical surfaces in the printer.

The optical cassette is exposed to contaminants during printing and while being handled between prints. Inspect and clean the optical cassette.

Step 2: Clean the upper laser window

Contamination can also build up on the upper laser window during printing, reducing the strength of the laser light reaching the powder. Inspect and clean the upper laser window.

Contacting Formlabs Support

If the troubleshooting steps above do not resolve the print failure, contact Formlabs Support or your certified service provider.

To help us provide the fastest and most effective response to your issue, please follow these steps:

  1. Upload diagnostic logs
  2. Serial name of the printer
  3. Troubleshooting steps attempted
    • Example: “I reoriented the model in PreForm. I inspected the optical window and did not notice any damage, clouding, or debris.”
  4. Powder type
  5. Relevant FORM files
    • If available, attach FORM files of the model to the support request.
  6. Previous attempts to print the part and any successful prints
    • Example: “I printed the file part2.form three times previously. The first and second were successful. The third one failed.”