Aluminum’s expansion coefficient is 0.000023m/C. Using my Voron, let’s say the z extrusions are 530mm long and my extrusions go from 22 °C to 55 °C. This means they grow 0.35mm. That’s in total, so the effect at the print head isn’t 0.35mm, but let’s say my gantry rides 25% of the way up. That’s 0.0875mm, which is roughly 3x the z-offset of my last print.