Calibration cross

thingiverse

Update 19.01.2020: Excel sheet V2.3 typo corrected at Z axis thanks to comments from fisero and Miiras. Update 18.03.2019: New Excel sheet V2! Now shrinking due to temperature change can be considered. Update 19.05.2019: Corrections on the excel sheet - V2.1. See comments from CoreCreation and The_Crab for details. Thanks, guys! Update 19.05.2019: Corrections on the excel sheet - V2.2. See comments from wspawn and KenayKustoms for details. Thanks, guys! This is the upgraded version of "Accurate calibration/dimension test". The upgrade has several changes: * X and Y are combined into one print * Over and under extrusion is evaluated * The method has slightly changed but the principle remains the same This test jig is designed to analyze dimensional accuracy of a printer using engineering methods. Don't worry, an excel sheet is included that performs all the math. You just have to print, measure, and type in the numbers. A caliper is required. Note that calibration is normally not needed for modern printers and calibration cubes are very coarse. Check this video: https://www.youtube.com/watch?v=Mbn1ckR86Z8 Why this method is more accurate than others: * Edges have chamfers to eliminate effects from first and last layers * Corners are rounded to minimize effects caused by sudden direction change * Unlike a calibration cube, the excel sheet analyzes the difference in column length instead of total length. This reduces influence of some effects that would distort the calibration like effective thicker walls due to z-wobble or over extrusion * It uses the total length available for typical calipers (150mm), reducing influence of random effects A derived recommendation for design tolerances is included based on a typical engineering approach (3sigma). The excel sheet is protected against unintended changes, but there's no password. So you can easily deactivate protection to edit formulas if needed. To get statistical data: If you've performed this test, please post the standard deviation for X and Y, printer, and slicer used in the comment section. Thanks in advance.