Quick guide to calibrating the scale of your 3D printer

So your past the painful phase of 3D printing balls of spaghetti and you are starting to get print shapes that are starting to look like they should. The only problem, they are not quite right. Holes that are supposed to be perfectly circular are turning out more like ovals. This is often a sign that firmware in your 3D printer needs a bit of calibration.

This is a companion discussion topic for the original entry at https://reprage.com/post/46062359808/quick-guide-to-calibrating-the-scale-of-your-3d-printer