No doubt I could discover this by trial and error, but are the alpha/beta/gamma_steps_per_mm values in the config file floating point numbers? In particular my Z axis doesn’t have a nice integer value to describe an exact millimeter of movement, so while it is close, the current setting prints things slightly too tall.
Sure, you can have significant numbers/digits/they are indeed floating point numbers. That’d be an extremely severe limitations if they weren’t, you’d probably see some way to add a divider value or something, so you can input those numbers as fractions. But no need for any of that, they are indeed floating point.
Added a pull request to the Smoothieware Github repository so the example configuration file will then reflect the answer to your question by making the beta steps per millimeter 333.3333 instead of 80.
Thanks. That should avoid confusion in the future from literal minded folks like me :-).