Calitower Z - An addition to the open source Calistar

Introduction

Just as Calistar, Calitower Z is a free, open source, and parametric tool used to adjust a 3D printer's dimensional accuracy. While Calistar calibrates the x- and y-axis, Calitower Z sets out to do exactly that, just for the 3D printer's z-axis. Calitower Z is inspired by Calistar and is designed based on Calistar's core principles. Simply transfer the knowledge gained about Calistar to Calitower Z and you will be good to go to get your 3D printer's z-axis dialed in. Note that Calitower Z does not support a z-axis scew calibration.

Notes on printing

• Use a layer height of 0.2 mm (or 0.1 mm). Otherwise, the nominal distance values between two measurement points are not guaranteed to be 120 mm, 80 mm, and 40 mm!

• Use the correct Calitowre Z version for the type of printed filament.

  • Rather stiff polymers (PLA, PETG, ABS, ASA, PC, Nylon, etc.) can easily be printed without any stiffening support structure. The correct files are the "calitower_z_stiff_<...>.<file_type>".

  • Flexible polymers (TPU, PEBA, etc.) require stiffening support structure. The correct files are the "calitower_z_flex_<...>.<file_type>".

Notes on measuring

• While the outer measurements are likely to represent the 3D printer's calibration quite accurately, the inner measurements might not. Even though bridging sections are kept at a minimum distance, their measurements are likely not 100 % accurate. The reasons are two-fold:

  • The droop will be ever so slight.

  • The extruded filament does not get squished against an underlying layer, but can radially extend almost equally in all directions.

  • Nevertheless, when handling these measurements diligently and taking one or two more samples per pair of measurment points, the results should be quite precise. That is at least what empirically showed.

Notes on provided files

• All of the model and print files can be found here on printables. The spreadsheet "Parametric Skew Calibration.xlsx" to calculate the printer's calibration accuracy may be downloaded from github.com.

• Calitower Z is currently only available in a 120x3 version. So a nominal 120 mm measurement height (144 mm print height required) with three distances for outer and inner measurements, respectively.

• Currently, only the "Parametric Skew Calibration.xlsx" has been modified to include dedicated input sections and output values for the z-axis. However, the browser-based version can be used just as well. Simply enter the z-measurements into either the x or y value sections and leave the rest empty. The results shown for the corresponding axis now refer to the z-axis.

Note: The gcode information in the header is for the "stiff" version utilizing PrusaSlicer's "balanced" print profile.