What are "magic numbers"?
The Z motor moves most precisely in full steps. With a 1.8° motor (200 steps per turn) and an 8 mm lead screw, one full step moves the nozzle 8 ÷ 200 = 0.04 mm. Layer heights that are multiples of 0.04 mm (0.12, 0.16, 0.20, 0.24, 0.28) avoid microstepping errors.
Z per full step = lead ÷ (360° ÷ step angle)
Good layers = n × Z per full step (≤ 80% of nozzle diameter)
With a 0.4 mm nozzle, keep layers between about 0.08 mm and 0.32 mm. Printers with 2 mm leads or 0.9° motors have finer steps (0.01–0.02 mm), so almost any value works.
Frequently asked questions
Is 0.2 mm a good layer height?
Yes. On an 8 mm lead screw 0.2 mm is exactly 5 full steps, and it balances speed and detail for a 0.4 mm nozzle.
What is the max layer height for a 0.4 mm nozzle?
About 0.32 mm (80% of the nozzle diameter).