Calibration Test Strip

thingiverse

Determining the dimensional accuracy and shrinkage ratio of a printer requires a large object that prints quickly. A thin 200mm test strip with hexagon ends is ideal for this purpose. This approach avoids errors caused by over or under extrusion on a 20mm calibration cube. Credit goes to Thomas Sanladerer, who introduced the idea of using calibration sticks in various sizes. However, he uses round holes and is more cautious about the accuracy of consumer 3D printers. You can find his designs on youmagine.com. To use this method, simply print a strip, let it cool, and measure from the pointed parts of the hole. The measurement should be exactly 200mm. Rotate the strip to align with the Y-axis in your slicer software and repeat. The math is straightforward. If you request 200mm but get a smaller measurement, like 190mm, increase the print size or steps per mm setting by creating a ratio greater than one: (200 / 190). Conversely, if it measures longer, such as 210mm, shrink the print or steps per mm by using a ratio less than one: (200 / 210). Then multiply the current setting by your desired ratio to get the new setting. In Cura 4.3.0, the Shrinkage Ratio seems to be locked in the FLSun QQ-S Profile. I'm not sure if this is related to Repetier or Delta printers. If dimensions are crucial for a print, you can still scale each axis of a model before printing.