Most hobby FDM owners on Bambu, Prusa, or Ender waste a full spool chasing the same first-layer fail.

The print is not the problem. The bed is.

Finger oil on PEI. Z a hair too high. First-layer speed still at 60 mm/s. Fan on from layer 1. Then they reprint the same STL five times and call the file bad.

Do this instead:

1. Wash the bed. Soap, water, dry. No IPA as the only clean if it is PEI.

2. Print a 5-square bed test, not the full model. Corners tell you more than the center.

3. First layer under 30 mm/s. Fan off for the first 3 layers on PLA.

4. If the second test still fails, stop. Take a photo. Changing ten settings at once hides the cause.

I built LayerFix around that loop: files that are actually print-ready, and a one-hour live rescue when the machine itself is the issue. Two separate products. No subscription. No fake lifetime support.

If you are stuck on a fail right now, that is the whole job.